1
|
Arora B, Jai-Chyi Pei K, Feng Weng C, Ching-Min Sun N. Measuring fecal metabolites of endogenous steroids using ESI-MS/MS spectra in Taiwanese pangolin, (order Pholidota, family Manidae, Genus: Manis): A non-invasive method for endangered species. Gen Comp Endocrinol 2020; 299:113607. [PMID: 32882210 DOI: 10.1016/j.ygcen.2020.113607] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 08/19/2020] [Accepted: 08/24/2020] [Indexed: 11/22/2022]
Abstract
Pangolins are 'keystone species' driven towards extinction due to a lack of profound awareness and illegal trade. The drivers urge for immediate development in the understanding of demographics and reproductive dynamics of this species. In this study, we developed and validated a quantitative method to measure pangolin fecal extracts using the electrospray (ESI-MS/MS) interface in positive ionization mode. The method aids in the measurement of hormones from the hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG) axis, making it a possibly appropriate technique to understand the cross-talk between the axes. The study aims to measure the relative abundance of adrenal and gonadal hormones such as corticosterone, cortisol, estrone, estradiol-17β, progesterone, testosterone, and a number of its metabolites. From the dried fecal extract, the principal metabolite identified from the estrogen family was estradiol-17β, whereas the gestagen family revealed that the pregnane series is predominated in 5α-configuration. On the other hand, epiandrosterone was seen as the dominant form in the male fecal extracts. Additionally, the glucocorticoids are excreted majorly as corticosterone, but traces of cortisol are also present in both the male and female fecal samples. The physiological validation confirmed that the ESI-MS/MS technique is suitable to determine physiologically caused differences in the fecal steroid concentrations. Physiologically, the age structure in pangolin is not responsible for causing differences within gender. However, the results revealed that glucocorticoids might vary between the sexes, i.e., males have a higher relative abundance of glucocorticoids over females. Therefore, our studies show that some of the main adrenal and gonadal metabolites can be predicted by exploiting MS/MS, which can steer research to potentially assess the reproductive status of captive and free-ranging pangolin species.
Collapse
Affiliation(s)
- Bharti Arora
- Department of Natural Resources and Environmental Studies, National Dong Hwa University, Taiwan.
| | - Kurtis Jai-Chyi Pei
- Institute of Wildlife Conservation, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Ching Feng Weng
- Department of Life Sciences, National Dong Hwa University, Taiwan
| | - Nick Ching-Min Sun
- Graduate Institute of Bioresources, National Pingtung University of Science and Technology, Pingtung, Taiwan
| |
Collapse
|
2
|
The Chronic and Unpredictable Stress Suppressed Kisspeptin Expression during Ovarian Cycle in Mice. JOURNAL OF ANIMAL REPRODUCTION AND BIOTECHNOLOGY 2019. [DOI: 10.12750/jarb.34.1.40] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
|
3
|
Zhu Q, Ge F, Li X, Deng HS, Xu M, Bu T, Li J, Wang Y, Shan Y, Ge RS, Yao M. Dehydroepiandrosterone Antagonizes Pain Stress-Induced Suppression of Testosterone Production in Male Rats. Front Pharmacol 2018; 9:322. [PMID: 29713278 PMCID: PMC5911460 DOI: 10.3389/fphar.2018.00322] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 03/20/2018] [Indexed: 11/13/2022] Open
Abstract
Background: Leydig cells secrete the steroid hormone, testosterone, which is essential for male fertility and reproductive health. Stress increases the secretion of glucocorticoid [corticosterone, (CORT) in rats] that decreases circulating testosterone levels in part through a direct action on its receptors in Leydig cells. Intratesticular CORT level is dependent on oxidative inactivation of CORT by 11β-hydroxysteroid dehydrogenase 1 (HSD11B1) in rat Leydig cells. Pain may cause the stress, thus affecting testosterone production in Leydig cells. Methods: Adult male Sprague–Dawley rats orally received vehicle control or 5 or 10 mg/kg dehydroepiandrosterone (DHEA) 0.5 h before being subjected to pain stimulation for 1, 3, and 6 h. In the present study, we investigated the time-course changes of steroidogenic gene expression levels after acute pain-induced stress in rats and the possible mechanism of DHEA that prevented it. Plasma CORT, luteinizing hormone (LH), and testosterone (T) levels were measured, and Leydig cell gene expression levels were determined. The direct regulation of HSD11B1 catalytic direction by DHEA was detected in purified rat Leydig, liver, and rat Hsd11b1-transfected COS1 cells. Results: Plasma CORT levels were significantly increased at hour 1, 3, and 6 during the pain stimulation, while plasma T levels were significantly decreased starting at hour 3 and 6. Pain-induced stress also decreased Star, Hsd3b1, and Cyp17a1 expression levels at hour 3. When 5 and 10 mg/kg DHEA were orally administered to rats 0.5 h before starting pain stimulation, DHEA prevented pain-mediated decrease in plasma T levels and the expression of Star, Hsd3b1, and Cyp17a1 without affecting plasma CORT levels. DHEA was found to modulate HSD11B1 activities by increasing its oxidative activity and decreasing its reductive activity, thus decreasing the intracellular CORT levels in Leydig cells. Conclusion: Stress induced by acute pain can inhibit Leydig cell T production by upregulation of corticosterone. DHEA can prevent the negative effects of excessive corticosterone by modulating HSD11B1 activity.
Collapse
Affiliation(s)
- Qiqi Zhu
- Department of Anesthesiology of the Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China
| | - Fei Ge
- Department of Anesthesiology of the Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China
| | - Xiaoheng Li
- Department of Anesthesiology of the Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China
| | - Hou-Sheng Deng
- Department of Anesthesiology of the Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China
| | - Miao Xu
- Department of Anesthesiology of the Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China
| | - Tiao Bu
- General Hospital of Guangzhou Military Command of PLA, Guangzhou, China
| | - Jingyang Li
- Department of Neonatology, Xi'an No.4 Hospital, Xi'an, China
| | - Yiyan Wang
- Department of Anesthesiology of the Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China
| | - Yuanyuan Shan
- Department of Anesthesiology of the Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China
| | - Ren-Shan Ge
- Department of Anesthesiology of the Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China
| | - Ming Yao
- Department of Anesthesiology of the Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China
| |
Collapse
|
4
|
Ralph CR, Lehman MN, Goodman RL, Tilbrook AJ. Impact of psychosocial stress on gonadotrophins and sexual behaviour in females: role for cortisol? Reproduction 2016; 152:R1-R14. [DOI: 10.1530/rep-15-0604] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 04/07/2016] [Indexed: 12/21/2022]
Abstract
This review focuses on the importance of cortisol in mediating the inhibitory effects of psychosocial stress on reproduction in females. In particular, we have summarized our research in sheep where we have systematically established whether cortisol is both sufficient and necessary to suppress reproductive hormone secretion and inhibit sexual behaviour. Our findings are put into context with previous work and are used to develop important concepts as well as to identify productive further lines of investigation. It is clear that cortisol is necessary to inhibit some, but not all, aspects of reproduction in female sheep. These actions vary with reproductive state, and there are important interactions with gonadal steroids. The impact of cortisol on the tonic secretion of gonadotrophin-releasing hormone and luteinizing hormone has been investigated extensively, but less is known about the surge secretion of these hormones and their effects on sexual behaviour. Furthermore, there are separate effects of cortisol in the brain (hypothalamus) and at the anterior pituitary, illustrating that there are different mechanisms of action. Thus, although cortisol is important in mediating some of the effects of stress on reproduction, we need to look beyond cortisol and investigate some of the other mechanisms and mediators that relay the effects of stress on reproduction. In this regard, we propose that a group of neurons in the hypothalamus that co-synthesize kisspeptin, neurokinin B and dynorphin, termed KNDy cells, play important roles in mediating the effects of cortisol on reproduction. This hypothesis needs to be rigorously tested.
Collapse
|
5
|
Luo E, Stephens SBZ, Chaing S, Munaganuru N, Kauffman AS, Breen KM. Corticosterone Blocks Ovarian Cyclicity and the LH Surge via Decreased Kisspeptin Neuron Activation in Female Mice. Endocrinology 2016; 157:1187-99. [PMID: 26697722 PMCID: PMC4769373 DOI: 10.1210/en.2015-1711] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Stress elicits activation of the hypothalamic-pituitary-adrenal axis, which leads to enhanced circulating glucocorticoids, as well as impaired gonadotropin secretion and ovarian cyclicity. Here, we tested the hypothesis that elevated, stress-levels of glucocorticoids disrupt ovarian cyclicity by interfering with the preovulatory sequence of endocrine events necessary for the LH surge. Ovarian cyclicity was monitored in female mice implanted with a cholesterol or corticosterone (Cort) pellet. Cort, but not cholesterol, arrested cyclicity in diestrus. Subsequent studies focused on the mechanism whereby Cort stalled the preovulatory sequence by assessing responsiveness to the positive feedback estradiol signal. Ovariectomized mice were treated with an LH surge-inducing estradiol implant, as well as Cort or cholesterol, and assessed several days later for LH levels on the evening of the anticipated surge. All cholesterol females showed a clear LH surge. At the time of the anticipated surge, LH levels were undetectable in Cort-treated females. In situ hybridization analyses the anteroventral periventricular nucleus revealed that Cort robustly suppressed the percentage of Kiss1 cells coexpressing cfos, as well as reduced the number of Kiss1 cells and amount of Kiss1 mRNA per cell, compared with expression in control brains. In addition, Cort blunted pituitary expression of the genes encoding the GnRH receptor and LHβ, indicating inhibition of gonadotropes during the blockage of the LH surge. Collectively, our findings support the hypothesis that physiological stress-levels of Cort disrupts ovarian cyclicity, in part, through disruption of positive feedback mechanisms at both the hypothalamic and pituitary levels which are necessary for generation of the preovulatory LH surge.
Collapse
Affiliation(s)
- Elena Luo
- Department of Reproductive Medicine and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, California 92093-0674
| | - Shannon B Z Stephens
- Department of Reproductive Medicine and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, California 92093-0674
| | - Sharon Chaing
- Department of Reproductive Medicine and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, California 92093-0674
| | - Nagambika Munaganuru
- Department of Reproductive Medicine and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, California 92093-0674
| | - Alexander S Kauffman
- Department of Reproductive Medicine and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, California 92093-0674
| | - Kellie M Breen
- Department of Reproductive Medicine and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, California 92093-0674
| |
Collapse
|
6
|
Legan SJ, Peng X, Yun C, Duncan MJ. Effect of arousing stimuli on circulating corticosterone and the circadian rhythms of luteinizing hormone (LH) surges and locomotor activity in estradiol-treated ovariectomized (ovx+EB) Syrian hamsters. Horm Behav 2015; 72:28-38. [PMID: 25958077 PMCID: PMC4466083 DOI: 10.1016/j.yhbeh.2015.04.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 04/28/2015] [Accepted: 04/29/2015] [Indexed: 12/21/2022]
Abstract
In most proestrous hamsters, novel wheel exposure phase advances activity rhythms and blocks the preovulatory LH surge, which occurs 2h earlier the next day. Because wheel immobilization does not prevent these effects we hypothesized that arousal alone blocks and phase advances the LH surge. Ovariectomized (ovx) hamsters received a jugular vein cannula and estradiol benzoate (EB) or vehicle was injected sc. The next day (Day 1), at zeitgeber time (ZT) 4-5 (ZT 12 = lights off), after obtaining a blood sample, each hamster was exposed to constant darkness (DD), and either remained in her home cage or was transferred to a new cage and exposed to a running wheel or a 2-hour arousal paradigm. Blood samples were obtained in dim red light and activity was recorded hourly until ~ZT 10-11 on Days 1 and 2. For the next 1-2 weeks, activity was monitored in DD. Plasma LH and corticosterone were assessed by RIA. Novel wheel exposure or arousal at ZT 4 greatly attenuated the Day 1 LH surge in ovx+EB hamsters, and phase advanced the Day 2 LH surge by about 2h. In proestrous hamsters, novel wheel exposure led to a prolonged (>2h) increase in corticosterone levels only when LH surges were blocked. Phase advances in activity rhythms were enhanced by estradiol and arousal. The results suggest that estradiol modulates the effectiveness of non-photic stimuli. The role of the increased activity of the hypothalamic-pituitary-adrenal axis associated with novel wheel-induced attenuation of LH surges in ovx+EB hamsters remains to be determined.
Collapse
Affiliation(s)
- S J Legan
- Department of Physiology, University of Kentucky, 800 Rose Street, Lexington, KY 40536-0298, USA.
| | - X Peng
- Department of Physiology, University of Kentucky, 800 Rose Street, Lexington, KY 40536-0298, USA.
| | - C Yun
- Department of Physiology, University of Kentucky, 800 Rose Street, Lexington, KY 40536-0298, USA.
| | - M J Duncan
- Department of Anatomy and Neurobiology, University of Kentucky, 800 Rose Street, Lexington, KY 40536-0298, USA.
| |
Collapse
|
7
|
Geraghty AC, Kaufer D. Glucocorticoid Regulation of Reproduction. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015. [PMID: 26215998 DOI: 10.1007/978-1-4939-2895-8_11] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
It is well accepted that stress, measured by increased glucocorticoid secretion, leads to profound reproductive dysfunction. In times of stress, glucocorticoids activate many parts of the fight or flight response, mobilizing energy and enhancing survival, while inhibiting metabolic processes that are not necessary for survival in the moment. This includes reproduction, an energetically costly procedure that is very finely regulated. In the short term, this is meant to be beneficial, so that the organism does not waste precious energy needed for survival. However, long-term inhibition can lead to persistent reproductive dysfunction, even if no longer stressed. This response is mediated by the increased levels of circulating glucocorticoids, which orchestrate complex inhibition of the entire reproductive axis. Stress and glucocorticoids exhibits both central and peripheral inhibition of the reproductive hormonal axis. While this has long been recognized as an issue, understanding the complex signaling mechanism behind this inhibition remains somewhat of a mystery. What makes this especially difficult is attempting to differentiate the many parts of both of these hormonal axes, and new neuropeptide discoveries in the last decade in the reproductive field have added even more complexity to an already complicated system. Glucocorticoids (GCs) and other hormones within the hypothalamic-pituitary-adrenal (HPA) axis (as well as contributors in the sympathetic system) can modulate the hypothalamic-pituitary-gonadal (HPG) axis at all levels-GCs can inhibit release of GnRH from the hypothalamus, inhibit gonadotropin synthesis and release in the pituitary, and inhibit testosterone synthesis and release from the gonads, while also influencing gametogenesis and sexual behavior. This chapter is not an exhaustive review of all the known literature, however is aimed at giving a brief look at both the central and peripheral effects of glucocorticoids on the reproductive function.
Collapse
Affiliation(s)
- Anna C Geraghty
- Department of Integrative Biology, University of California, Berkeley, CA, USA
| | | |
Collapse
|
8
|
Willis CKR, Wilcox A. Hormones and hibernation: possible links between hormone systems, winter energy balance and white-nose syndrome in bats. Horm Behav 2014; 66:66-73. [PMID: 24768718 DOI: 10.1016/j.yhbeh.2014.04.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 04/11/2014] [Accepted: 04/15/2014] [Indexed: 12/19/2022]
Abstract
This article is part of a Special Issue "Energy Balance". Hibernation allows mammals to survive in cold climates and during times of reduced food availability. Drastic physiological changes are required to maintain the energy savings that characterize hibernation. These changes presumably enable adjustments in endocrine activity that control metabolism and body temperature, and ultimately influence expression of torpor and periodic arousals. Despite challenges that exist when examining hormonal pathways in small-bodied hibernators, bats represent a potential model taxon for comparative neuroendocrinological studies of hibernation due to their diversity of species and the reliance of many species on heterothermy. Understanding physiological mechanisms underlying hibernation in bats is also important from a conservation physiology perspective due to white-nose syndrome, an emerging infectious disease causing catastrophic mortality among hibernating bats in eastern North America. Here we review the potential influence of three key hormonal mechanisms--leptin, melatonin and glucocorticoids--on hibernation in mammals with an emphasis on bats. We propose testable hypotheses about potential effects of WNS on these systems and their evolution.
Collapse
Affiliation(s)
- Craig K R Willis
- Department of Biology and Centre for Forest Interdisciplinary Research, University of Winnipeg, Winnipeg, MB, Canada.
| | - Alana Wilcox
- Department of Biology and Centre for Forest Interdisciplinary Research, University of Winnipeg, Winnipeg, MB, Canada
| |
Collapse
|
9
|
Son YL, Ubuka T, Narihiro M, Fukuda Y, Hasunuma I, Yamamoto K, Belsham DD, Tsutsui K. Molecular basis for the activation of gonadotropin-inhibitory hormone gene transcription by corticosterone. Endocrinology 2014; 155:1817-26. [PMID: 24552400 DOI: 10.1210/en.2013-2076] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The inhibitory effect of stress on reproductive function is potentially mediated by high concentrations of circulating glucocorticoids (GCs) acting via the GC receptor (GR). Gonadotropin-inhibitory hormone (GnIH) is a hypothalamic neuropeptide that inhibits gonadotropin secretion. GnIH may mediate stress-induced reproductive dysfunction. However, it is not yet known whether GC-bound GR is directly involved in GnIH transcription. Here, we demonstrated the localization of GR mRNA in GnIH neurons in the paraventricular nucleus of quail, suggesting that GC can directly regulate GnIH transcription. We next showed that 24 hours of treatment with corticosterone (CORT) increase GnIH mRNA expression in the quail diencephalon. We further investigated the mechanism of activation of GnIH transcription by CORT using a GnIH-expressing neuronal cell line, rHypoE-23, derived from rat hypothalamus. We found the expression of GR mRNA in rHypoE-23 cells and increased GnIH mRNA expression by 24 hours of CORT treatment. We finally characterized the promoter activity of rat GnIH gene stimulated by CORT. Through DNA deletion analysis, we identified a CORT-responsive region at 2000-1501 bp upstream of GnIH precursor coding region. This region included 2 GC response elements (GREs) at -1665 and -1530 bp. Mutation of -1530 GRE abolished CORT responsiveness. We also found CORT-stimulated GR recruitment at the GnIH promoter region containing the -1530 GRE. These results provide a putative molecular basis for transcriptional activation of GnIH under stress by demonstrating that CORT directly induces GnIH transcription by recruitment of GR to its promoter.
Collapse
Affiliation(s)
- You Lee Son
- Laboratory of Integrative Brain Sciences (Y.L.S., T.U., M.N., Y.F., I.H., K.Y., K.T.), Department of Biology, Waseda University, and Center for Medical Life Science of Waseda University, Tokyo 162-8480, Japan; and Departments of Physiology (D.D.B.), Medicine, and Obstetrics and Gynaecology, University of Toronto, and Division of Cellular and Molecular Biology, Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada M5S 1A8
| | | | | | | | | | | | | | | |
Collapse
|
10
|
Takumi K, Iijima N, Higo S, Ozawa H. Immunohistochemical analysis of the colocalization of corticotropin-releasing hormone receptor and glucocorticoid receptor in kisspeptin neurons in the hypothalamus of female rats. Neurosci Lett 2012; 531:40-5. [PMID: 23069671 DOI: 10.1016/j.neulet.2012.10.010] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 09/26/2012] [Accepted: 10/04/2012] [Indexed: 10/27/2022]
Abstract
Kisspeptin, a neuropeptide encoded by Kiss1 gene, plays pivotal roles in the regulation of reproductive function. Recently various stressors and stress-induced molecules such as corticotropin-releasing hormone (CRH) and corticosterone have been shown to inhibit Kiss1 expression in rat hypothalamus. To determine whether CRH and glucocorticoids directly act on kisspeptin neurons, we examined the colocalization of CRH receptor (CRH-R) and glucocorticoid receptor (GR) in kisspeptin neurons in the female rat hypothalamus. Double-labeling immunohistochemistry revealed that most kisspeptin neurons in the anteroventral periventricular nucleus and periventricular nucleus continuum (AVPV/PeN), and arcuate nucleus (ARC) expressed CRH-R. We also observed a few close appositions of CRH immunoreactive fibers on some of kisspeptin neurons in AVPV/PeN and ARC. On the other hand, most kisspeptin neurons in AVPV/PeN expressed GR, whereas only a few of kisspeptin neurons in ARC expressed GR. Altogether, our study provides neuroanatomical evidence of the direct modulation of kisspeptin neurons by CRH and glucocorticoids and suggests that stress-induced CRH and glucocorticoids inhibit gonadotropin secretion via the kisspeptin system.
Collapse
Affiliation(s)
- Ken Takumi
- Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan
| | | | | | | |
Collapse
|
11
|
Kosowska B, Zdrojewicz Z. Relationship between inbreeding and sex-hormone concentration in rats under stress. I. The effect of various inbreeding levels on pituitary sex-hormone concentrations in two types of stress. J Anim Breed Genet 2011. [DOI: 10.1111/j.1439-0388.1996.tb00597.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
12
|
Wu XQ, Li XF, Ye B, Popat N, Milligan SR, Lightman SL, O'Byrne KT. Neonatal programming by immunological challenge: effects on ovarian function in the adult rat. Reproduction 2011; 141:241-8. [PMID: 21084570 PMCID: PMC3021912 DOI: 10.1530/rep-10-0252] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Revised: 11/01/2010] [Accepted: 11/17/2010] [Indexed: 11/14/2022]
Abstract
Neonatal exposure to an immunological challenge (lipopolysaccharide, LPS) increases the activity of hypothalamo-pituitary-adrenal axis and sensitises the GNRH pulse generator to the inhibitory influence of stress in adult rats. We investigated the effects of neonatal exposure to LPS on various reproductive parameters during puberty and into adulthood in female rats. LPS (50 μg/kg, i.p.) or saline was administered on postnatal days 3 and 5. Vaginal opening was recorded, and oestrous cyclicity was monitored immediately post puberty and again at 8-9 weeks of age. At 10 weeks of age, the ovaries were removed and the number of follicles was counted, together with the thickness of the theca interna of the largest antral follicles. Ovarian sympathetic nerve activity was assessed immunohistochemically by measurement of the levels of ovarian low-affinity receptor of nerve growth factor (p75NGFR). In rats exposed to LPS in early life, there was a significant delay in puberty and disruption of oestrous cyclicity immediately post puberty, which persisted into adulthood. The follicle reserve was decreased, the thickness of the theca interna increased and the expression profile of ovarian p75NGFR increased in the neonatal LPS-treated animals. These data suggest that exposure to LPS during early neonatal life can have long-term dysfunctional effects on the female reproductive system, which might involve, at least in part, increased ovarian sympathetic nerve activity.
Collapse
Affiliation(s)
- Xue-Qing Wu
- Division of Women's Health, School of MedicineKing's College LondonGuy's Campus, 2.95W Hodgkin Building, London, SE1 1ULUK
- First Affiliated Hospital of Wenzhou Medical CollegeWenzhou, 325000People's Republic of China
| | - Xiao-Feng Li
- Division of Women's Health, School of MedicineKing's College LondonGuy's Campus, 2.95W Hodgkin Building, London, SE1 1ULUK
| | - Bilu Ye
- First Affiliated Hospital of Wenzhou Medical CollegeWenzhou, 325000People's Republic of China
| | - Neha Popat
- Division of Women's Health, School of MedicineKing's College LondonGuy's Campus, 2.95W Hodgkin Building, London, SE1 1ULUK
| | - Stuart R Milligan
- Division of Women's Health, School of MedicineKing's College LondonGuy's Campus, 2.95W Hodgkin Building, London, SE1 1ULUK
| | - Stafford L Lightman
- Henry Wellcome Laboratory for Integrative Neuroscience and EndocrinologyUniversity of BristolBristol, BS1 3NYUK
| | - Kevin T O'Byrne
- Division of Women's Health, School of MedicineKing's College LondonGuy's Campus, 2.95W Hodgkin Building, London, SE1 1ULUK
- First Affiliated Hospital of Wenzhou Medical CollegeWenzhou, 325000People's Republic of China
| |
Collapse
|
13
|
Herod SM, Dettmer AM, Novak MA, Meyer JS, Cameron JL. Sensitivity to stress-induced reproductive dysfunction is associated with a selective but not a generalized increase in activity of the adrenal axis. Am J Physiol Endocrinol Metab 2011; 300:E28-36. [PMID: 20959528 PMCID: PMC3023200 DOI: 10.1152/ajpendo.00223.2010] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Stress-induced reproductive dysfunction is a relatively common cause of infertility in women. In response to everyday life stress, some individuals readily develop reproductive dysfunction (i.e., they are stress sensitive), whereas others are more stress resilient. Female cynomolgus monkeys, when exposed to mild combined psychosocial and metabolic stress (change in social environment + 20% reduced calorie diet), can be categorized as stress sensitive (SS; they rapidly become anovulatory in response to stress), medium stress resilient (MSR; they slowly become anovulatory in response to prolonged stress), or highly stress resilient (HSR; they maintain normal menstrual cycles in response to stress). In this study, we examined whether increased sensitivity to stress-induced reproductive dysfunction is associated with elevated adrenal axis activity by measuring 1) the diurnal release of ACTH and cortisol, 2) ACTH and cortisol in response to an acute psychological stress, 3) the percent suppression of cortisol in response to dexamethasone negative feedback, 4) the diurnal release of ACTH and cortisol following exposure to mild psychosocial and metabolic stress, 5) the concentration of cortisol in hair, and 6) adrenal weight. SS monkeys (n = 5) did not differ from MSR (n = 5) or HSR (n = 7) monkeys in any measurement of baseline HPA axis activity or the integrated measurements of chronic HPA axis activity. However, MSR + SS monkeys (n = 10) did secrete more cortisol than HSR monkeys during the daytime hours (1000-1800) following exposure to a novel social environment and reduced diet. We conclude that increased activity of the HPA axis is unlikely to be the primary mechanism causing increased sensitivity to stress-induced reproductive dysfunction.
Collapse
Affiliation(s)
- S. M. Herod
- 1Department of Behavioral Neuroscience and
- 2Division of Reproductive Science, Oregon National Primate Research Center, Oregon Health and Science University, Portland, Oregon;
| | | | - M. A. Novak
- 3Neuroscience and Behavior Program and
- 4Department of Psychology, University of Massachusetts, Amherst, Massachusetts;
| | - J. S. Meyer
- 3Neuroscience and Behavior Program and
- 4Department of Psychology, University of Massachusetts, Amherst, Massachusetts;
| | - J. L. Cameron
- 1Department of Behavioral Neuroscience and
- 2Division of Reproductive Science, Oregon National Primate Research Center, Oregon Health and Science University, Portland, Oregon;
- 5Department of Obstetrics and Gynecology, Oregon National Primate Research Center, Oregon Health and Science University, Portland, Oregon; and
- 6Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pennsylvania
| |
Collapse
|
14
|
Pierce BN, Clarke IJ, Turner AI, Rivalland ETA, Tilbrook AJ. Cortisol disrupts the ability of estradiol-17beta to induce the LH surge in ovariectomized ewes. Domest Anim Endocrinol 2009; 36:202-8. [PMID: 19185443 DOI: 10.1016/j.domaniend.2008.11.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2008] [Revised: 11/19/2008] [Accepted: 11/24/2008] [Indexed: 11/30/2022]
Abstract
Stress disrupts the preovulatory luteinizing hormone (LH) surge in females, but the mechanisms are unknown. We tested the hypothesis that cortisol compromises the ability of estrogen to induce a preovulatory-like LH surge in ovariectomized ewes in both the breeding and nonbreeding season. Luteinizing hormone surges were induced in ovariectomized ewes by treatment with progesterone followed by a surge-inducing estradiol-17beta (E2) stimulus using a crossover design. The experiment was replicated in the breeding and nonbreeding seasons. Cortisol reduced the incidence of LH surges irrespective of season. Cortisol increased the latency from E2 stimulus to the onset of the surge in the breeding season only and suppressed the LH surge amplitude during both seasons (P<0.01). We conclude that cortisol can interfere with the LH surge in several ways: delay, blunt, and in extreme cases prevent the E2-induced LH surge. Furthermore, the effect of cortisol to delay the E2-induced LH surge is more pronounced in the breeding season. These results show that cortisol disrupts the positive feedback effect of E2 to trigger an LH surge and suggest the involvement of multiple mechanisms.
Collapse
Affiliation(s)
- B N Pierce
- Department of Physiology, Monash University, Victoria, 3800, Australia
| | | | | | | | | |
Collapse
|
15
|
Wagenmaker ER, Breen KM, Oakley AE, Pierce BN, Tilbrook AJ, Turner AI, Karsch FJ. Cortisol interferes with the estradiol-induced surge of luteinizing hormone in the ewe. Biol Reprod 2008; 80:458-63. [PMID: 19056703 DOI: 10.1095/biolreprod.108.074252] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Two experiments were conducted to test the hypothesis that cortisol interferes with the positive feedback action of estradiol that induces the luteinizing hormone (LH) surge. Ovariectomized sheep were treated sequentially with progesterone and estradiol to create artificial estrous cycles. Cortisol or vehicle (saline) was infused from 2 h before the estradiol stimulus through the time of the anticipated LH surge in the artificial follicular phase of two successive cycles. The plasma cortisol increment produced by infusion was approximately 1.5 times greater than maximal concentrations seen during infusion of endotoxin, which is a model of immune/inflammatory stress. In experiment 1, half of the ewes received vehicle in the first cycle and cortisol in the second; the others were treated in reverse order. All ewes responded with an LH surge. Cortisol delayed the LH surge and reduced its amplitude, but both effects were observed only in the second cycle. Experiment 2 was modified to provide better control for a cycle effect. Four treatment sequences were tested (cycle 1-cycle 2): vehicle-vehicle, cortisol-cortisol, vehicle-cortisol, cortisol-vehicle. Again, cortisol delayed but did not block the LH surge, and this delay occurred in both cycles. Thus, an elevation in plasma cortisol can interfere with the positive feedback action of estradiol by delaying and attenuating the LH surge.
Collapse
Affiliation(s)
- Elizabeth R Wagenmaker
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | | | | | | | | | | | | |
Collapse
|
16
|
Hu GX, Lian QQ, Lin H, Latif SA, Morris DJ, Hardy MP, Ge RS. Rapid mechanisms of glucocorticoid signaling in the Leydig cell. Steroids 2008; 73:1018-24. [PMID: 18281069 PMCID: PMC2561306 DOI: 10.1016/j.steroids.2007.12.020] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2007] [Accepted: 12/11/2007] [Indexed: 11/15/2022]
Abstract
Stress-mediated elevations in circulating glucocorticoid levels lead to corresponding rapid declines in testosterone production by Leydig cells in the testis. In previous studies we have established that glucocorticoids act on Leydig cells directly, through the classic glucocorticoid receptor (GR), and that access to the GR is controlled prior to the GR by a metabolizing pathway mediated by the type 1 isoform of 11beta-hydroxysteroid dehydrogenase (11betaHSD1). This enzyme is bidirectional (with both oxidase and reductase activities) and in the rat testis is exclusively localized in Leydig cells where it is abundantly expressed and may catalyze the oxidative inactivation of glucocorticoids. The predominant reductase direction of 11betaHSD1 activity in liver cells is determined by an enzyme, hexose-6-phosphate dehydrogenase (H6PDH), on the luminal side of the smooth endoplasmic reticulum (SER). Generation of the pyridine nucleotide cofactor NADPH by H6PDH stimulates the reductase direction of 11betaHSD1 resulting in increased levels of active glucocorticoids in liver cells. Unlike liver cells, steroidogenic enzymes including 17beta-hydroxysteroid dehydrogenase 3 (17betaHSD3) forms the coupling with 11betaHSD1. Thus the physiological concentrations of androstenedione serve as a substrate for 17betaHSD3 utilizing NADPH to generate NADP+, which drives 11betaHSD1 in Leydig cells primarily as an oxidase; thus eliminating the adverse effects of glucocorticoids on testosterone production. At the same time 11betaHSD1 generates NADPH which promotes testosterone biosynthesis by stimulating 17betaHSD3 in a cooperative cycle. This enzymatic coupling constitutes a rapid mechanism for modulating glucocorticoid control of testosterone biosynthesis. Under stress conditions, glucocorticoids also have rapid actions to suppress cAMP formation thus to lower testosterone production.
Collapse
Affiliation(s)
- Guo-Xin Hu
- Institute of Molecular Toxicology and Pharmacology, School of Pharmacy, Wenzhou Medical College, Wenzhou, Zhejiang 325035, P.R. China
- Population Council and The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
| | - Qing-Quan Lian
- Institute of Neuroendocrinology and the 2 Affiliated Hospital, Wenzhou Medical College, Wenzhou, Zhejiang 325000, P.R. China
| | - Han Lin
- Population Council and The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
- Institute of Neuroendocrinology and the 2 Affiliated Hospital, Wenzhou Medical College, Wenzhou, Zhejiang 325000, P.R. China
| | - Syed A. Latif
- The Miriam Hospital, Brown University School of Medicine, Providence, RI 02906, USA
| | - David J. Morris
- The Miriam Hospital, Brown University School of Medicine, Providence, RI 02906, USA
| | | | - Ren-Shan Ge
- Institute of Molecular Toxicology and Pharmacology, School of Pharmacy, Wenzhou Medical College, Wenzhou, Zhejiang 325035, P.R. China
- Population Council and The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
- Institute of Neuroendocrinology and the 2 Affiliated Hospital, Wenzhou Medical College, Wenzhou, Zhejiang 325000, P.R. China
- Correspondence: Ren-Shan Ge, Population Council, 1230 York Avenue, New York, NY 10021, USA, Tel.: 212-327-8754; Fax: 212-327-7678, E-mail:
| |
Collapse
|
17
|
Matsuwaki T, Kayasuga Y, Yamanouchi K, Nishihara M. Maintenance of gonadotropin secretion by glucocorticoids under stress conditions through the inhibition of prostaglandin synthesis in the brain. Endocrinology 2006; 147:1087-93. [PMID: 16293664 DOI: 10.1210/en.2005-1056] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We have previously reported that glucocorticoids counteract the suppressive effects of tumor necrosis factor-alpha on both pulsatile and surge secretion of LH. This suggests that glucocorticoids have a protective effect on reproductive function under infectious stress. In the present study, we examined whether glucocorticoids maintain pulsatile LH secretion under various conditions of acute stress and the possible involvement of prostaglandins (PGs) in glucocorticoid actions. Three different types of stressors, namely infectious (lipopolysaccharide, 0.5 microg/kg), hypoglycemic (2-deoxy-D-glucose, 100 mg/kg), and restraint stress (1 h) were applied to ovariectomized rats. In ovariectomized rats, LH pulses were partially suppressed by restraint, but not by lipopolysaccharide or 2-deoxy-D-glucose. On the other hand, adrenalectomy (ADX) significantly enhanced the suppressive effects of all the stressors applied on LH pulses. Treatment with both corticosterone (25 mg/kg) and indomethacin (10 mg/kg) in ADX rats significantly attenuated the suppressive effects of these stressors on LH pulses. In addition, the immunoreactivity of cyclooxygenase-2, a PG-synthesizing enzyme, in the brain under stress conditions was much enhanced by ADX, and this was counteracted by corticosterone treatment. Similarly, an increase in body temperature under restraint stress was enhanced by ADX and suppressed by corticosterone. These results suggest that suppression of LH pulsatility by stress is mediated by PGs in the brain, and that increased release of endogenous glucocorticoids in response to stress counteracts this suppression by inhibiting PG synthesis, and thereby maintains reproductive function regardless of the nature of the stressor.
Collapse
Affiliation(s)
- Takashi Matsuwaki
- Department of Veterinary Physiology, Veterinary Medical Science, University of Tokyo, Tokyo 113-8657, Japan
| | | | | | | |
Collapse
|
18
|
Hardy MP, Gao HB, Dong Q, Ge R, Wang Q, Chai WR, Feng X, Sottas C. Stress hormone and male reproductive function. Cell Tissue Res 2005; 322:147-53. [PMID: 16079965 DOI: 10.1007/s00441-005-0006-2] [Citation(s) in RCA: 192] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2005] [Accepted: 05/11/2005] [Indexed: 10/25/2022]
Abstract
The Leydig cell is the primary source of testosterone in males. Levels of testosterone in circulation are determined by the steroidogenic capacities of individual Leydig cells and the total numbers of Leydig cells per testis. Stress-induced increases in serum glucocorticoid concentrations inhibit testosterone-biosynthetic enzyme activity, leading to decreased rates of testosterone secretion. It is unclear, however, whether the excessive glucocorticoid stimulation also affects total Leydig cell numbers through induction of apoptosis and thereby contributes to the stress-induced suppression of androgen levels. Exposure of Leydig cells to high concentrations of corticosterone (CORT, the endogenously secreted glucocorticoid in rodents) increases their frequency of apoptosis. Studies of immobilization stress indicate that stress-induced increases in CORT are directly responsible for Leydig cell apoptosis. Access to glucocorticoid receptors in Leydig cells is modulated by oxidative inactivation of glucocorticoid by 11 beta-hydroxysteroid dehydrogenase (11 betaHSD). Under basal levels of glucocorticoid, sufficient levels of glucocorticoid metabolism occur and there is likely to be minimal binding of the glucocorticoid receptor. We have established that Leydig cells express type 1 11 betaHSD, an oxidoreductase, and type 2, a unidirectional oxidase. Generation of redox potential through synthesis of the enzyme cofactor NADPH, a byproduct of glucocorticoid metabolism by 11 betaHSD-1, may potentiate testosterone biosynthesis, as NADPH is the cofactor used by steroidogenic enzymes such as type 3 17beta-hydroxysteroid dehydrogenase. In this scenario, inhibition of steroidogenesis will only occur under stressful conditions when high input amounts of CORT exceed the capacity of oxidative inaction by 11 betaHSD. Changes in autonomic catecholaminergic activity may contribute to suppressed Leydig cell function during stress, and may explain the rapid onset of inhibition. However, recent analysis of glucocorticoid action in Leydig cells indicates the presence of a fast, non-genomic pathway that will merit further investigation.
Collapse
Affiliation(s)
- Matthew P Hardy
- Center for Biomedical Research, Population Council, New York, NY 10021, USA.
| | | | | | | | | | | | | | | |
Collapse
|
19
|
Aschauer A, Hoffmann IE, Millesi E. Endocrine profiles and reproductive output in European ground squirrels after unilateral ovariectomy. Anim Reprod Sci 2005; 92:392-400. [PMID: 16046255 DOI: 10.1016/j.anireprosci.2005.06.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2004] [Revised: 05/02/2005] [Accepted: 06/10/2005] [Indexed: 10/25/2022]
Abstract
In the course of a long-term study on reproductive physiology and behaviour in female European ground squirrels (Spermophilus citellus) we investigated interactions among reproductive timing, maternal effort and hibernation. To gain information on the state of follicular development shortly before hibernation, histological investigations of ovaries were carried out. To collect the ovaries, unilateral ovariectomy was chosen as the least invasive method. The aim of this study was to monitor patterns of hormone secretion, behavioural parameters and reproductive output in females after unilateral ovariectomy, and compare them with intact individuals to assess potential effects of the treatment. Reproductive performance including duration of gestation and lactation, litter size, and offspring mass at natal emergence were similar in treated and untreated individuals. Before weaning, plasma estradiol levels were higher in the hemicastrated group than in intact females. Progesterone concentrations tended to be lower in unilaterally ovariectomized females during gestation and postlactation. In both groups we measured cortisol metabolites in fecal samples to estimate basal adrenal activity. Untreated individuals had significantly higher cortisol levels than hemicastrated females during lactation. In all other phases no significant differences in patterns of cortisol excretion were found between the two groups. Prehibernatory body-mass did not differ between treated and untreated females. These results indicate that unilateral ovariectomy had no significant negative effects on reproductive timing and output in female European ground squirrels. Compensatory activity of the remaining ovary does occur, concerning estradiol secretion even a kind of overcompensation was reported. These elevated estradiol levels in unilaterally ovariectomized females could play a role in limiting the degree of follicular compensation.
Collapse
Affiliation(s)
- Anna Aschauer
- Department of Neurobiology and Behavioural Sciences, University of Vienna, Althanstr. 14, 1090 Vienna, Austria.
| | | | | |
Collapse
|
20
|
Matsuwaki T, Watanabe E, Suzuki M, Yamanouchi K, Nishihara M. Glucocorticoid maintains pulsatile aecretion of luteinizing hormone under infectious stress condition. Endocrinology 2003; 144:3477-82. [PMID: 12865328 DOI: 10.1210/en.2002-221111] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We have previously shown that TNF-alpha, a major proinflammatory cytokine, suppressed hypothalamic GnRH pulse generator activity and that this inhibitory effect was enhanced by alpha-helical CRH, a CRH receptor antagonist. The present study was conducted to elucidate the involvement of glucocorticoid (GC) in modulating LH pulses under infectious stress condition. Adrenalectomy (ADX) markedly enhanced the suppressive effect of TNF-alpha (1 micro g), injected iv, on LH pulses in ovariectomized (OVX) rats. Pretreatment with a sc injection of corticosterone (10 mg) almost completely restored LH pulses after TNF-alpha injection in OVX/ADX animals. Injection of TNF-alpha increased the number of c-Fos-immunoreactive cells in the supraoptic nucleus (SON), the dorsomedial hypothalamic nucleus (DMH), and the parvocellular region of the paraventricular nucleus (PVN), which was more prominent in OVX/ADX than OVX animals except in the DMH. Pretreatment with corticosterone decreased the number of Fos-immunoreactive cells in the PVN and SON but not in the DMH. These results suggest that GC has a potent protective effect on LH pulsatility under conditions of infectious stress, the mechanism of which involves at least the suppression of the excitability of PVN and SON neurons. In addition, the DMH does not seem to mediate the central action of GC, though it may play an important role in inducing pathophysiological reactions to invasive stress.
Collapse
Affiliation(s)
- Takashi Matsuwaki
- Department of Veterinary Physiology, Veterinary Medical Science, The University of Tokyo, Tokyo 113-8657, Japan
| | | | | | | | | |
Collapse
|
21
|
Tohei A, Sakamoto S, Kogo H. Dexamethasone or triamcinolone increases follicular development in immature female rats. JAPANESE JOURNAL OF PHARMACOLOGY 2000; 84:281-6. [PMID: 11138728 DOI: 10.1254/jjp.84.281] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We have previously reported that dexamethasone increased follicle-stimulating hormone (FSH) secretion via suppression of inhibin in immature female rats. In the present study, we investigated the effects of dexamethasone or triamcinolone on follicular development and ovarian functions (estradiol and inhibin secretion) in equine chorionic gonadotropin (eCG)-primed immature female rats. Dexamethasone significantly increased the number of ovulated oocytes in immature female rats treated with 5 i.u. eCG. Serum concentration of FSH in eCG-treated female rats was increased by administration of dexamethasone or triamcinolone, showing the peak value at 9 h after its administration, although the levels of inhibin markedly decreased at that time. Serum concentrations of inhibin and estradiol in eCG-treated female rats increased at 24 h after administration of dexamethasone or triamcinolone. These results demonstrate that dexamethasone or triamcinolone increases FSH secretion, and the excess amount of FSH strongly stimulates follicular development cooperating with exogenous eCG.
Collapse
Affiliation(s)
- A Tohei
- Department of Pharmacology, Tokyo University of Pharmacy and Life Science, Hachioji, Japan
| | | | | |
Collapse
|
22
|
Miller GK, Valerio MG, Pino MV, Larson JL, Viau A, Hamelin N, Labbé R, Banks CM. Chronic effects of the novel glucocorticosteroid RPR 106541 administered to beagle dogs by inhalation. Toxicol Pathol 2000; 28:226-36. [PMID: 10805140 DOI: 10.1177/019262330002800202] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The preclinical safety of RPR 106541, a novel 17-thiosteroid, was evaluated in young adult and mature dogs by inhalation exposure for 26 weeks and 52 weeks, respectively. A dry powder formulation of RPR 106541 in lactose was administered to young adult dogs (approximately 6 months of age at initiation) at doses of 0 (air and placebo controls), 10, 100, or 1,000 microg/kg/d for 26 weeks. A solution-based aerosol formulation was administered to mature dogs (approximately 10 months at initiation) from a pressurized metered dose inhaler at 0 (air and placebo controls), 10, 50, and 150 microg/kg/d for 52 weeks. Clinical evidence of glucocorticosteroid-induced immunosuppression was observed by weeks 20-26 following relatively high dose exposures (100 microg/kg/d and 1,000 microg/kg/d) in young dogs receiving the dry powder formulation for 26 weeks. Classic glucocorticosteroid effects were observed, including adrenocortical atrophy, reduced bone mass with retention of epiphyseal growth plates in long bones, prominence of stromal adipose tissue in bone marrow, and atrophy of lymphoid tissues. Inhalation administration of RPR 106541 to sexually mature dogs facilitated more definitive characterization of endocrine affects of RPR 106541 as compared with administration in younger, sexually immature animals. Significant effects in female reproductive organs included absence of corpora lutea in association with atresia of vesicular follicles within the ovaries, endometrial hyperplasia, and lobular development of mammary tissue. Discordant development of mammary tissue, accumulation of secretory material within hyperplastic endometrial glands, and hypertrophy of uterine lining epithelium in absence of ovulation were consistent with a secondary progestin effect by a potent glucocorticosteroid.
Collapse
Affiliation(s)
- G K Miller
- Rhône-Poulenc Rorer Research and Development, Collegeville, Pennsylvania 19426-0994, USA.
| | | | | | | | | | | | | | | |
Collapse
|
23
|
Tohei A, Kogo H. Dexamethasone increases follicle-stimulating hormone secretion via suppression of inhibin in rats. Eur J Pharmacol 1999; 386:69-74. [PMID: 10611465 DOI: 10.1016/s0014-2999(99)00722-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In the present study, the effects of dexamethasone on follicle-stimulating hormone (FSH) secretion in immature female rats were investigated. Dexamethasone increased the selective secretion of FSH and decreased plasma concentrations of inhibin in immature female rats. The effects of dexamethasone on FSH secretion were not confirmed in rats treated with ovariectomy or immunoneutralization against inhibin. In addition to the direct effect of dexamethasone on FSH synthesis in gonadotrophs, the present study has clearly demonstrated that the increased level of FSH in dexamethasone-treated rats is mediated by suppression of ovarian function, especially by the inhibition of inhibin secretion.
Collapse
Affiliation(s)
- A Tohei
- Department of Pharmacology, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Japan
| | | |
Collapse
|
24
|
Calogero AE, Burrello N, Bosboom AM, Garofalo MR, Weber RF, D'Agata R. Glucocorticoids inhibit gonadotropin-releasing hormone by acting directly at the hypothalamic level. J Endocrinol Invest 1999; 22:666-70. [PMID: 10595829 DOI: 10.1007/bf03343627] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Glucocorticoids, the end-product of the hypothalamic-pituitary-adrenal (HPA) axis, suppress gonadotropin release by acting at the level of the pituitary gland. However, experimental evidence suggests that they may also act at the hypothalamic level to suppress gonadotropin-releasing hormone (GnRH) release. The lack of a direct demonstration of this assumption, prompted us to evaluate the effects of glucocorticoids on hypothalamic GnRH release from individually-incubated hemi-hypothalami explanted from male rats. Since testosterone (T), dihydrotestosterone (DHT), and progesterone suppress GnRH release and androgens potentiate the effects of glucocorticoids on GnRH release, we studied also the interaction of these steroids with glucocorticoids on GnRH release. Corticosterone (B), the main glucocorticoid of the rodents with greater affinity for the type I glucocorticoid receptor, and dexamethasone (DEX), a synthetic type II glucocorticoid receptor agonist, were able to suppress basal GnRH release in a concentration-dependent fashion. DEX induced a more profound suppression of GnRH release. Neither T (0.1 nM) nor DHT (0.01 nM) modulated the suppressive effects of low (10 nM) or high (100 nM) concentrations of B on GnRH release. On the other hand, progesterone counteracted the suppressive effect of low concentrations of B (10 nM) on GnRH release, but had no effect on the suppression caused by a higher concentration of B (100 nM). The ability of glucocorticoids to inhibit directly GnRH release suggests that these stress-responsive hormones act also at the hypothalamic level to suppress the reproductive function. The suppressive effect of B was not modulated by androgens, but it was neutralized by progesterone, at least when B was used at low concentrations. We speculate that this steroid "protects" the GnRH-secreting neuron only during basal, but not stress-induced, HPA axis activity when the concentrations of glucocorticoids are more elevated.
Collapse
Affiliation(s)
- A E Calogero
- Divisione di Andrologia, Dipartimento di Medicina Interna, Università di Catania, Italy.
| | | | | | | | | | | |
Collapse
|
25
|
Mantzavinos T, Phocas I, Vitoratos N, Photopoulos S, Hassiakos D, Antoniou G. Comparison between steroid hormones and cortisol in serum and follicular fluid in stimulated and unstimulated cycles of in vitro fertilization patients. Gynecol Endocrinol 1997; 11:163-8. [PMID: 9209896 DOI: 10.3109/09513599709152530] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The present study was undertaken to evaluate the effects of the concentrations of serum and follicular fluid steroids and cortisol levels on the establishment of pregnancies in in vitro fertilization (IVF). Our study group consisted of 42 women (group A) who received gonadotropins for induction of ovulation for IVF. The control group included 23 women (group B) who underwent in vitro fertilization without stimulation. Serum estradiol and progesterone levels were significantly higher in group A than in group B. Serum and follicular fluid cortisol levels were similar in both groups A and B. There was no significant difference in the fertilization rates of the stimulated or unstimulated cycles. However, there were no pregnancies in group B whereas there was a 28.5% pregnancy rate in group A. There were no correlations between the estradiol, progesterone and cortisol levels when compared to the oocyte maturity and the fertilization rates in both groups of patients.
Collapse
Affiliation(s)
- T Mantzavinos
- 2nd Department of Obstetrics and Gynecology, University of Athens, Areteion Hospital, Greece
| | | | | | | | | | | |
Collapse
|
26
|
Misiewicz B, Griebler C, Gomez M, Raybourne R, Zelazowska E, Gold PW, Sternberg EM. The estrogen antagonist tamoxifen inhibits carrageenan induced inflammation in LEW/N female rats. Life Sci 1996; 58:PL281-6. [PMID: 8614285 DOI: 10.1016/0024-3205(96)00106-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Carrageenan induces a measurable inflammatory response in susceptible animals, and mature females are more responsive to carrageenan, than males. In the present study, we tested whether the estrogen antagonist tamoxifen influences carrageenan-induced inflammatory responses. Female LEW/N rats were treated with tamoxifen and compared to a control group of animals injected with vehicle. Tamoxifen significantly reduced estrous phase of estrous cycle during treatment, consistent with its functional anti-estrogen effects. Moreover, tamoxifen significantly decreased exudate volume but did not significantly influence relative white blood cell counts in the exudate. Interestingly, tamoxifen induced differential dose-dependent alterations in peripheral blood lymphocyte subpopulations. Low dose of tamoxifen increased CD25 cells. The high tamoxifen dose significantly increased CD8 blood lymphocytes counts. Our data indicate that tamoxifen treatment decreases carrageenan-induced inflammatory response in female LEW/N rats and suggest therefore that this inflammatory response is, at least in part, estrogen related. Moreover, our results suggest a possible role for tamoxifen in treatment of inflammatory disorders.
Collapse
Affiliation(s)
- B Misiewicz
- Clinical Neuroendocrinology Branch, National Institute of Mental Health, Bethesda, MD 20892, USA
| | | | | | | | | | | | | |
Collapse
|
27
|
Mendes MC, Ferriani RA, Costa LO, Moura MD, Silva de Sá MF. Cortisol levels alter the response to metoclopramide in patients with hypothalamic amenorrhea. Gynecol Endocrinol 1995; 9:9-14. [PMID: 7793305 DOI: 10.3109/09513599509160185] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The reduction in frequency and/or amplitude of gonadotropin-releasing hormone (GnRH) pulses in patients with amenorrhea of hypothalamic origin has been attributed to increased dopamine activity. The objective of the present study was to determine the role of dopamine in the pathogenesis of hypothalamic amenorrhea. Fourteen patients with hypothalamic amenorrhea, nine of whom had psychogenic amenorrhea and five anorexia nervosa, were studied and compared with nine normal women during the early follicular phase. Metoclopramide (10 mg), a dopamine antagonist, was infused intravenously and blood samples were collected at 15-min intervals for 2 h for follicle-stimulating hormone (FSH) and luteinizing hormone (LH) measurement by radioimmunoassay. Both the hypothalamic amenorrhea (psychogenic amenorrhea and anorexia nervosa) and control groups were unresponsive to FSH, suggesting that dopamine may have little or no effect on FSH secretion. Five patients of the psychogenic amenorrhea group responded to LH (responsive psychogenic amenorrhea) and four did not (non-responsive psychogenic amenorrhea). No anorexia nervosa or control patient responded to the stimulus. Responsive psychogenic amenorrhea patients showed decreased basal cortisol levels compared to the non-responsive psychogenic amenorrhea and anorexia nervosa groups. It is possible that patients with exclusive alterations in the dopaminergic system are those who respond to metoclopramide (responsive psychogenic amenorrhea group), whereas patients who also have involvement of the hypothalamic-adrenal axis like the women with anorexia nervosa, are not responsive to metoclopramide and tend to have elevated cortisol levels. The non-responsive psychogenic amenorrhea group, with elevated cortisol levels, probably represents an intermediate step between the responsive psychogenic amenorrhea and anorexia nervosa patients.
Collapse
Affiliation(s)
- M C Mendes
- Department of Gynecology and Obstetrics, University of São Paulo, Brazil
| | | | | | | | | |
Collapse
|
28
|
Briski KP, Vogel KL. Role of endogenous opioid peptides in central glucocorticoid receptor (GR)-induced decreases in circulating LH in the male rat. Neuropeptides 1995; 28:175-81. [PMID: 7791961 DOI: 10.1016/0143-4179(95)90113-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
While it has been shown that intracerebral administration of exogenous glucocorticoids diminishes pituitary luteinizing hormone (LH) release, it is not known if these hormones act directly on gonadotropin-releasing hormone (GnRH)-synthesizing neurons, or if their central inhibitory effects are mediated by specific neural substrates. In the present study, we examined whether the opioid receptor antagonist, naltrexone (NALT), alters patterns of LH release elicited by either systemic or intracerebroventricular (i.c.v.) delivery of GR agonists. Subcutaneous (s.c.) injection of the GR agonist, RU362 (2.5 mg/kg), promoted a significant reduction in circulating LH levels; pretreatment by i.c.v. injection of 1.0 microgram NALT, however, attenuated this inhibitory hormonal response. It was also found that rats treated sequentially with NALT and RU362 exhibited significantly lower plasma LH levels compared to rats injected with NALT alone. In other experiments, intracranial delivery of the synthetic glucocorticoid, dexamethasone (DEX), into either the ventricular system or the hypothalamic ARC resulted in significantly decreased plasma LH concentrations; the central inhibitory effects of DEX on peripheral LH release were reversed, however, by i.c.v. pretreatment with NALT. In summary, the present studies show that opioid receptor blockade attenuates systemic, as well as intracerebral inhibitory effects of GR agonists on the GnRH-pituitary LH axis, suggesting that circulating glucocorticoids inhibit LH, in part, through central actions involving endogenous opioid receptors. The observed decline in peripheral plasma LH following intra-ARC injection of DEX suggests that local GR may be functional target sites for glucocorticoid effects on LH.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- K P Briski
- Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, College of Veterinary Medicine, Washington State University, Pullman 99164-6520, USA
| | | |
Collapse
|
29
|
Briski KP. Effects of peripheral versus central administration of the endogenous glucocorticoid, corticosterone, and the glucocorticoid receptor agonist, RU 28362, on LH release in male rats. Brain Res 1995; 670:66-74. [PMID: 7719726 DOI: 10.1016/0006-8993(94)01263-h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The current studies evaluated the effects of the synthetic glucocorticoid receptor (GR) agonist, RU 28362, and the endogenous, non-selective receptor ligand, corticosterone (Cort), on pituitary luteinizing hormone (LH) secretion in male rats. Steroids were injected subcutaneously (s.c.) in animals previously implanted with intracardiac venous catheters, or administered intracerebroventricularly (i.c.v.) to other groups of animals. A dose-proportionate decrease in plasma LH was observed following either s.c. or i.c.v. administration of RU 28362; pretreatment with the GR antagonist, RU 38486, blunted the inhibitory impact of RU 28362 on circulating LH. In other experiments, s.c. injection of Cort elicited divergent, dose-dependent patterns of LH release. While the lowest peripheral dose (0.25 mg Cort/kg) promoted a transient elevation in plasma LH, higher doses exerted a progressively greater inhibitory effect on hormone release. The suppressive effects of the highest s.c. dose (2.5 mg Cort/kg) were reversed by pretreatment with the RU 38486, but not by the mineralocorticoid receptor antagonist, RU 26752. Plasma LH levels were transiently elevated following i.c.v. administration of graded doses of Cort. The lowest dose (0.1 microgram Cort/rat) only facilitated LH release, but higher doses (1.0 and 10.0 micrograms/animal) elicited a biphasic LH response, which was characterized by an initial elevation, then subsequent reduction in plasma LH below preinjection baseline levels. Prior administration of the mineralocorticoid receptor antagonist, RU 26752, attenuated the stimulatory impact of i.c.v. Cort on LH release, while both RU 26752 and RU 38486 reversed the secondary decline in plasma LH.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- K P Briski
- Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, College of Veterinary Medicine, Washington State University, Pullman 99164-6520, USA
| |
Collapse
|
30
|
Albiston AL, Smith RE, Krozowski ZS. Changes in the levels of 11 beta-hydroxysteroid dehydrogenase mRNA over the oestrous cycle in the rat. J Steroid Biochem Mol Biol 1995; 52:45-8. [PMID: 7857872 DOI: 10.1016/0960-0760(94)00154-e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The NADP dependent enzyme 11 beta-hydroxysteroid dehydrogenase (11 beta HSD) metabolizes glucocorticoids to their inactive 11-keto-metabolites in a wide range of tissues. To date very little is known about the regulation of this enzyme at the level of gene transcription. In this study we show significant changes in the uterine, renal, ovarian and hepatic levels of 11 beta HSD1 mRNA over the oestrous cycle. Uterine and renal message levels followed the same pattern, with the highest levels observed at dioestrus and the lowest levels at oestrus, a pattern that correlates with plasma oestrogen levels during the cycle. In both the uterus and kidney 11 beta HSD1 message levels more than halved from dioestrus to oestrus, while renal levels than doubled at metoestrus. In contrast, hepatic 11 beta HSD1 message levels at prooestrus were twice those observed at metoestrus. Ovarian levels remain constant until metoestrus when a marked decrease in message levels was seen. 11 beta HSD1 mRNA levels are thus differentially regulated in a tissue specific manner throughout the oestrous cycle.
Collapse
Affiliation(s)
- A L Albiston
- Baker Institute for Medical Research, Prahran, Australia
| | | | | |
Collapse
|
31
|
Michael AE, Cooke BA. A working hypothesis for the regulation of steroidogenesis and germ cell development in the gonads by glucocorticoids and 11 beta-hydroxysteroid dehydrogenase (11 beta HSD). Mol Cell Endocrinol 1994; 100:55-63. [PMID: 8056159 DOI: 10.1016/0303-7207(94)90279-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The relationship between glucocorticoid secretion from the adrenal gland and gonadal function has previously been attributed to central inhibition by the adrenal steroids of pituitary gonadotropin output. This review focuses on the direct actions of glucocorticoids within the gonads, including positive effects on germ cell maturation and both positive and negative effects on the stimulation of gonadal steroidogenesis by LH and FSH. In addition, we address the role in the gonads of 11 beta-hydroxysteroid dehydrogenase (11 beta HSD), which interconverts the glucocorticoids with their inactive 11-ketosteroid derivatives. To date, two isoforms of 11 beta HSD have been described. 11 beta HSD1, purified and cloned from the liver, has a relatively low affinity for glucocorticoids and acts instead as an 11-oxoreductase, whereas the high affinity 11 beta HSD2, first identified in the kidney, acts as an efficient 11 beta-dehydrogenase to inactivate physiological concentrations of glucocorticoid. We propose that in the gonads, 11 beta HSD1 promotes the positive effects of glucocorticoids on germ cell maturation (by increasing the local concentration of active glucocorticoids), whereas a high affinity 11 beta-dehydrogenase activity, consistent with that of 11 beta HSD2, inactivates glucocorticoids and so protects luteal cells from the inhibitory effects of these steroids during the luteal phase of the ovarian cycle.
Collapse
Affiliation(s)
- A E Michael
- Department of Biochemistry, Royal Free Hospital School of Medicine, London, UK
| | | |
Collapse
|
32
|
Li PH. Actions of corticotropin-releasing factor or cortisol on follicle-stimulating hormone secretion by isolated pig pituitary cells. Life Sci 1993; 53:141-51. [PMID: 8390596 DOI: 10.1016/0024-3205(93)90661-l] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
This study investigated the direct effects of hydrocortisone (HS), corticotropin-releasing factor (CRF), and adrenocorticotropin (ACTH) on basal and gonadotropin-releasing hormone (GnRH)-stimulated secretion of follicle-stimulating hormone (FSH) from dispersed pig pituitary cells in vitro. Pig pituitaries were dispersed into cells with collagenase, DNAase, and hyaluronidase and then cultured in McCoy's 5a medium containing horse serum (10%) and fetal calf serum (2.5%) pretreated with dextran-coated charcoal for 3 days. Cells were preincubated with steroids, CRF, or ACTH before GnRH was added. HS did not affect basal FSH secretion after 72 h of incubation. Treatment of pituitary cells with increasing concentrations (0.001-800 micrograms/ml) of HS for 72 h resulted in a dose-dependent decrease in GnRH-stimulated FSH release. HS pretreatment did not cause a change in cellular FSH content. Increasing duration (6-72 h) of treatment with HS (200 micrograms/ml) led to a time-dependent decrease in GnRH-stimulated FSH release, achieving statistical significance by 12 h. Porcine ACTH had no influence on basal and GnRH-stimulated FSH secretion. CRF decreased GnRH-stimulated FSH secretion in a dose-dependent manner, and the inhibitory effect required preincubation (6-18 h) with CRF. HS inhibited the FSH secretory responses to phospholipase C, melittin, and 8-bromo-cAMP but did not affect the response to 1,2-dioctanoyl-sn-glycerol and ionophore A23187. These results indicate that both cortisol and CRF can act directly on pig pituitary to inhibit FSH responsiveness to GnRH.
Collapse
Affiliation(s)
- P H Li
- Department of Physiology, College of Medicine, National Cheng Kung University, Tainan, Taiwan, Republic of China
| |
Collapse
|
33
|
Chatterton RT, Kazer RR, Rebar RW. Depletion of luteal phase serum progesterone during constant infusion of cortisol phosphate in the cynomolgus monkey*†*Supported by grant HD 21921 from the National Institutes of Health, Bethesda, Maryland.†Presented at the 71st Annual Meeting of the Endocrine Society, Seattle, Washington, June 21, 1989. Fertil Steril 1991. [DOI: 10.1016/s0015-0282(16)54556-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
34
|
Abstract
Behavioral stress can prevent animals from achieving normal reproductive success. Stressors associated with intensive livestock management may be responsible for reduced reproductive efficiency. However, before appropriate management decisions can be made to alleviate the effects of behavioral stress on reproduction, it is necessary to identify the mechanisms by which stress disrupts normal reproduction. The neuroendocrine regulation of follicular development and ovulation requires a complex and delicate interplay between the pituitary gonadotropins and the feedback actions of the major follicular steroid, estradiol. Because of this complexity, the regulation of the follicular stage of the estrous cycle and ovulation is especially vulnerable to the effects of stress. Although the pathophysiological mechanisms by which stress disrupts reproduction are not fully understood, the stress-induced secretion of adrenal glucocorticoids seems to be of special significance because these steroids can effect both the synthesis and secretion of gonadotropins. Of additional importance may be the role of corticotropin-releasing hormone and adrenocorticotropin on the regulation of the hypothalamic-pituitary-gonadal axis.
Collapse
Affiliation(s)
- G P Moberg
- Department of Animal Science, University of California, Davis 95616
| |
Collapse
|
35
|
López-Calderón A, Ariznavarreta C, González-Quijano MI, Tresguerres JA, Calderón MD. Stress induced changes in testis function. J Steroid Biochem Mol Biol 1991; 40:473-9. [PMID: 1958548 DOI: 10.1016/0960-0760(91)90217-s] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The mechanism through which chronic stress inhibits the hypothalamic-pituitary-testicular axis has been investigated. Chronic restraint stress decreases testosterone secretion, an effect that is associated with a decrease in plasma gonadotropin levels. In chronically stressed rats there was a decrease in hypothalamic luteinizing hormone-releasing hormone (LHRH) content and the response on plasma gonadotropins to LHRH administration was enhanced. Thus the inhibitory effect of chronic stress on plasma LH and FSH levels seems not to be due to a reduction in pituitary responsiveness to LHRH, but rather to a modification in LHRH secretion. It has been suggested that beta-endorphin might interfere with hypothalamic LHRH secretion during stress. Chronic immobilization did not modify hypothalamic beta-endorphin, while an increase in pituitary beta-endorphin secretion was observed. Since we cannot exclude that changes in beta-endorphin secreted by the pituitary or other opioids may play some role in the stress-induced decrease in LHRH secretion, the effect of naltrexone administration on plasma gonadotropin was studied in chronically stressed rats. Naltrexone treatment did not modify the decrease in plasma concentrations of LH or FSH. These findings suggest that the inhibitory effect of restraint on the testicular axis is exerted at hypothalamic level by some mechanism other than opioids.
Collapse
Affiliation(s)
- A López-Calderón
- Departamento de Fisiología, Facultad de Medicina, Universidad Complutense, Madrid, Spain
| | | | | | | | | |
Collapse
|
36
|
Bider D, Pariente C, Dor J, Zolti M, Mashiach S, Ben-Rafael Z. Aromatase activity of human granulosa cells in patients with polycystic ovaries treated with dexamethasone. Fertil Steril 1990; 54:597-600. [PMID: 2209879 DOI: 10.1016/s0015-0282(16)53814-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The effect of dexamethasone (DEX) (9 alpha-Fluro-16 alpha-methyl prednisolone) on secretion of steroids by human granulosa luteinized cells was studied by culturing cells from mature follicles of women with polycystic ovarian disease and treated for infertility in the in vitro fertilization program. Patients were treated with DEX 0.5 mg/d until the day of human chorionic gonadotropin administration. The cells were cultured for 24 hours in the presence of androstenedione (10(-7)M). After incubating for 24 hours, the medium was replaced and the cells were incubated for an additional 24 hours. The medium was then harvested and assayed for estradiol (E2) and progesterone (P). Results were compared with those of a control group who was not treated with DEX. Estradiol production by cells was significantly lower in the study group treated with DEX. Progesterone production was not influenced by DEX. Follicular fluid levels, E2, and androgens did not vary with DEX treatment, whereas cortisol levels markedly decreased and P levels increased with the treatment. These findings suggest that glucocorticosteroids can directly influence granulosa luteinized cell function.
Collapse
Affiliation(s)
- D Bider
- Chaim Sheba Medical Center, Tel Aviv University, Tel Hashomer, Israel
| | | | | | | | | | | |
Collapse
|
37
|
Inazu N, Iwata N, Satoh T. Inhibitory effect of glucocorticoid and stimulatory effect of human chorionic gonadotropin on ovarian carbonyl reductase in rats. Life Sci 1990; 46:841-8. [PMID: 1690834 DOI: 10.1016/0024-3205(90)90113-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Effects of three glucocorticoids on ovulation, and on content and activity of ovarian carbonyl reductase in rats were investigated. Glucocorticoid treatment caused both significant decrease in ovarian and uterine weights, blockade of ovulation and marked decrease in content and activity of ovarian carbonyl reductase. Furthermore, the weak immunoreactivity to antibody against ovarian carbonyl reductase was shown in the theca cells and the interstitial gland cells in the glucocorticoid-treated ovary. The treatment with hCG (LH activity specific) restored the ovarian weight, and both the content and activity of ovarian carbonyl reductase, which were inhibited by glucocorticoids, to control level as well as ovulation. These results indicate that the ovarian carbonyl reductase may be closely involved in ovarian function, especially ovulation, and may be an LH-dependent enzyme, because it is well known that glucocorticoids inhibit both LH surge and ovulation in rats.
Collapse
Affiliation(s)
- N Inazu
- Department of Pharmacology and Toxicology, Tokyo College of Pharmacy, Japan
| | | | | |
Collapse
|
38
|
Fateh M, Ben-Rafael Z, Benadiva CA, Mastroianni L, Flickinger GL. Cortisol levels in human follicular fluid. Fertil Steril 1989; 51:538-41. [PMID: 2920855 DOI: 10.1016/s0015-0282(16)60572-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
This study shows that cortisol levels in follicular fluids in stimulated cycles were correlated with oocyte maturity and in vitro fertilizability. The levels were significantly higher than the concentrations found in spontaneous cycles. Our findings suggest that the presence of cortisol in follicular fluid may play a role in follicular development and oocyte maturation.
Collapse
Affiliation(s)
- M Fateh
- Department of Obstetrics and Gynecology, Hospital of the University of Pennsylvania, School of Medicine, Philadelphia
| | | | | | | | | |
Collapse
|
39
|
Abstract
The metabolic-endocrine state of diabetes mellitus affects the brain and behavior of diabetic animals. Feeding, paradoxical sleep, analgesia, submissive behavior, and avoidance behavior, are generally increased in diabetic compared with nondiabetic rodents. In contrast, sexual behavior, aggressive behavior and sensitivity to the behavioral effects of amphetamine are decreased in diabetic rodents. This review examines behavioral changes in diabetes mellitus within the context of known disease-linked alterations in hypothalamo-pituitary relationships and brain monoamine metabolism.
Collapse
Affiliation(s)
- L J Leedom
- Department of Psychiatry, Harbor-UCLA Medical Center, Torrance 90509
| | | |
Collapse
|
40
|
Phelps CP, Saporta S. The release of pituitary LH and sprouting of LH-releasing hormone (LHRH)-containing neurons after anterior hypothalamic deafferentation. Brain Res 1988; 454:188-204. [PMID: 3044516 DOI: 10.1016/0006-8993(88)90818-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The chronology of changes in plasma luteinizing hormone (LH) and the distribution of immunoreactive neuronal processes containing LH releasing hormone (LHRH-ir) were studied in the female rat after surgical interruption of anterior neural connections of the mediobasal hypothalamus (MBH). Spontaneous LH surges on the afternoon of proestrus and LH release after estradiol benzoate (EB) followed 48 h later by progesterone (P) administration were studied in ovariectomized (OVX) rats. The maximum increase in plasma concentrations (delta maxLH) after EBP was calculated for each rat at several intervals over 140 days. Control animals given EBP at monthly intervals after OVX had comparably large delta maxLH surges during the first few months of study. However, a gradual decline in control delta maxLH followed becoming significant 3 months after the start of the experiment. In contrast, frontal cuts (FC), which interrupted anterior MBH connections, produced an abrupt decrease in delta maxLH surges after EBP to 11% of preoperative levels. However, during subsequent EBP trials, there was a gradual improvement in LH surges to about 50% of preoperative levels over 100 days. In some cases, individual improvement became equal to preoperative LH surge levels, in others there was no recovery. Examination of LHRH-ir nerve fiber growth responses after FC suggested that sprouting by these peptide-containing neuronal processes may have contributed to the functional improvements observed.
Collapse
Affiliation(s)
- C P Phelps
- Department of Anatomy, College of Medicine, University of South Florida, Tampa 33612
| | | |
Collapse
|
41
|
Ben-Rafael Z, Benadiva CA, García CJ, Flickinger GL. Cortisol stimulation of estradiol and progesterone secretion by human granulosa cells is independent of follicle-stimulating hormone effects**Supported by the United States Public Health Services grant HD 06274-14 and by the Mellon Foundation.††Presented at the Fifth World Congress on in Vitro Fertilization and Embryo Transfer, Norfolk, Virginia, April 5 to 10, 1987. Fertil Steril 1988. [DOI: 10.1016/s0015-0282(16)59889-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
42
|
Vreeburg JT, Samaun K, Verkade HJ, Verhoef P, Ooms MP, Weber RF. Effects of corticosterone on the negative feedback action of testosterone, 5 alpha-dihydrotestosterone and estradiol in the adult male rat. JOURNAL OF STEROID BIOCHEMISTRY 1988; 29:93-8. [PMID: 3126366 DOI: 10.1016/0022-4731(88)90381-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Corticosterone acetate (10 mg/day) was administered to gonadectomized and adrenalectomized male rats bearing 5, 10 or 15 mm long testosterone filled silicone elastomer capsules. It was found that the serum testosterone levels induced by these capsules were not influenced by corticosterone treatment and that the weights of the prostates in the corticosterone treated rats were not different from their controls. In contrast, corticosterone acetate increased markedly the LH and FSH inhibitory effects of testosterone. Since several brain structures are able to convert testosterone into 17-beta-hydroxy-5-alpha-androstan-3-one (5-alpha-dihydrotestosterone) and/or estradiol, and these metabolites are probably involved in mechanisms controlling gonadotropin secretion, we studied also the effects of corticosterone on the feedback action of dihydrotestosterone and estradiol. 5 alpha-Dihydrotestosterone was administered by 5, 10 or 20 mm long elastomere capsules whereas estradiol was given by daily s.c. injections of 0.125, 0.25 or 0.50 micrograms estradiol benzoate. In the presence of corticosterone acetate the gonadotropin inhibitory action of testosterone, 5 alpha-dihydrotestosterone and estradiol increased more than 2 times.
Collapse
Affiliation(s)
- J T Vreeburg
- Department of Endocrinology, Growth and Reproduction, Erasmus University, Rotterdam, The Netherlands
| | | | | | | | | | | |
Collapse
|
43
|
Abstract
An enzymatically dispersed pituitary preparation from male Japanese quail (Coturnix coturnix) was used to study the effects of gonadal and adrenal steroids on gonadotropin release. Cells were preincubated for 18 hr with or without steroids and then challenged with chicken luteinizing hormone-releasing hormone (cLH-RH I; Gln8-LH-RH). Preincubation with testosterone (T; 10 nM) significantly suppressed (P less than 0.05) luteinizing hormone release in response to cLH-RH I (10 ng/ml). Preincubation with 5 alpha-dihydrotestosterone (5 alpha-DHT) (10 nM) caused even further suppression of LH-RH-stimulated LH release while the same concentration of 5 beta-dihydrotestosterone and estradiol-17 beta had no effect. In addition, preincubation with corticosterone (10 nM) significantly (P less than 0.01) suppressed the amount of LH released in response to cLH-RH I. Pituitary cells from immature males, when stimulated with cLH-RH I, released LH in a dose-related manner. Neither T nor 5 alpha-DHT (10 nM) altered the effect of LH-RH. These data suggest that T and 5 alpha-DHT play a role in mediating LH release in the avian pituitary while 5 beta-reduced androgens have no effect. There appears to be no androgen effect in the immature quail. In addition, corticosterone seems to be a factor in controlling gonadotropin secretion in the quail.
Collapse
Affiliation(s)
- P B Connolly
- Department of Biology, Boston University, Massachusetts 02215
| | | |
Collapse
|
44
|
Briski KP, Sylvester PW. Effects of sequential acute stress exposure on stress-induced pituitary luteinizing hormone and prolactin secretion. Life Sci 1987; 41:1249-55. [PMID: 3626756 DOI: 10.1016/0024-3205(87)90203-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The present study was carried out to determine the effects of repetitive acute stress exposure on pituitary secretion of both luteinizing hormone (LH) and prolactin (PRL). Adult male rats were exposed to sequential episodes of acute novel environment stress separated by intervals of either 60 or 120 minutes. Serial blood samples were obtained from animals before, during and after each stress episode via indwelling intra-cardiac cannulas. The imposition of 10 minute episodes of novel environment stress on an hourly basis eventually rendered the hypothalamic-hypophyseal LH axis refractory to the stimulatory effect of stress. If sequential stress was imposed at 120 minute intervals, LH release was significantly enhanced during each exposure. A different pattern of PRL release was observed during the same sequential stress schedule. After an initial increase in hormone release in response to the first hourly stress episode, PRL levels were unaltered during the second and third hourly stress exposures. Thereafter, plasma PRL levels showed a trend toward a progressive increase in release during each successive episode, and were significantly elevated above preceding baseline levels during the fourth and fifth hourly stress exposures. In rats exposed to stress every two hours, a significant increase in PRL levels occurred following the first, but not the second stress episode. Hormone release was again enhanced in response to the third exposure to novel environment. The present results demonstrate that the repetitive exposure to acute novel environment stress results in differential alterations in pituitary LH and PRL secretion over time, and that the timing of repeated episodes is an important determinant of continued responsiveness to stress, particularly with regard to LH release. These findings suggest that the LH and PRL hormonal responses to at least this specific stressor are mediated by independent neural mechanisms.
Collapse
|
45
|
Ringstrom SJ, Schwartz NB. Differential effect of glucocorticoids on synthesis and secretion of luteinizing hormone (LH) and follicle stimulating hormone (FSH). JOURNAL OF STEROID BIOCHEMISTRY 1987; 27:625-30. [PMID: 2826893 DOI: 10.1016/0022-4731(87)90362-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Our previous work has suggested that glucocorticoid pretreatment suppresses the enhanced responsiveness to GnRH seen in serum LH 12 h after castration. By contrast, serum FSH continues to show the castration-induced hypersensitivity to GnRH. Our attempts to replicate this LH suppression in static pituitary culture in vitro were not successful. This suggested to us the possibility that corticoids in vivo might be preventing castration-induced increases in pituitary GnRH receptor levels. We tested this at 24 h post-castration and, in fact, corticoids did not suppress the increase in GnRH receptors. In addition to the aforementioned effects of corticoids, we have seen that cortisol reverses the castration-induced drop in pituitary FSH content. It does this for 7 days post-castration, even though it no longer has an effect in suppressing serum LH. Thus, our accumulated data reveal that glucocorticoids have a differential effect on LH and FSH synthesis and secretion. Further studies are needed to clarify the site(s) of action of glucocorticoids in gonadotropin secretion and synthesis. Glucocorticoids may well prove to be a key in unlocking the mystery of the mechanism of differential control of regulation of LH and FSH.
Collapse
Affiliation(s)
- S J Ringstrom
- Department of Natural Science, Loyola University of Chicago, IL 60626
| | | |
Collapse
|
46
|
Lopez-Calderon A, Ariznavarreta C, Calderon MD, Tresguerres JA. Gonadotropin inhibition during chronic stress: role of the adrenal gland. JOURNAL OF STEROID BIOCHEMISTRY 1987; 27:609-14. [PMID: 3121926 DOI: 10.1016/0022-4731(87)90360-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The effect of adrenalectomy, metyrapone and dexamethasone treatments on gonadotropin response to chronic stress were studied. Adult male rats were submitted to chronic restraint (6 h daily over 4 days). At the end of the last stress period animals were decapitated and trunk blood was collected. Chronic restraint evoked a decrease in plasma LH and to a lesser degree in plasma FSH in the intact rat. Adrenalectomy did not prevent the LH reduction induced by stress and magnified the inhibitory effect of restraint on FSH secretion. Administration of the corticosterone synthesis blocker metyrapone increased the inhibitory effect of restraint on plasma LH and to a lesser degree on plasma FSH. Dexamethasone treatment did not significantly modify plasma gonadotropin levels in adrenalectomized unstressed rats, but this treatment totally blocked plasma LH and FSH reduction after chronic restraint. These results indicate that plasma LH and FSH reduction during chronic restraint is not due to the increase in glucocorticoid secretion, but seems to be mediated by the increase of the hypothalamic-pituitary components of the adrenal axis.
Collapse
Affiliation(s)
- A Lopez-Calderon
- Department of Physiology, Faculty of Medicine, Complutense University, Madrid, Spain
| | | | | | | |
Collapse
|
47
|
Raeside J, Xun HC. Direct effect of cortisol on androstenedione production by thecal cells from porcine ovarian follicles. Anim Reprod Sci 1986. [DOI: 10.1016/0378-4320(86)90015-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
48
|
Rivier C, Rivier J, Vale W. Stress-induced inhibition of reproductive functions: role of endogenous corticotropin-releasing factor. Science 1986; 231:607-9. [PMID: 3003907 DOI: 10.1126/science.3003907] [Citation(s) in RCA: 337] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In the adult castrated male rat, exposure to inescapable, intermittent electroshocks inhibited the pulsatile pattern of luteinizing hormone release and markedly lowered its plasma concentrations. The central administration of the corticotropin-releasing factor (CRF) antagonist alpha-helical ovine CRF residues 9 to 41 reversed the inhibitory action of stress. Neither its peripheral injection, nor the intraventricular injection of the inactive CRF analog des-Glu to Arg ovine CRF was effective. These results suggest that endogenous CRF may mediate some deleterious effects of noxious stimuli on reproduction.
Collapse
|
49
|
Rivier C, Vale W. Effect of the long-term administration of corticotropin-releasing factor on the pituitary-adrenal and pituitary-gonadal axis in the male rat. J Clin Invest 1985; 75:689-94. [PMID: 2982917 PMCID: PMC423559 DOI: 10.1172/jci111748] [Citation(s) in RCA: 75] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The effect of the continuous exposure to ovine corticotropin-releasing factor (oCRF) was measured in adult male rats. The intravenous infusion of 0.75 nmol oCRF/h to intact rats over a 24-h period was accompanied by a peak of ACTH and corticosterone secretion that occurred during the first 90 min of administration of the releasing factor, followed by a decrease to lower, but still above control, values. Additionally, corticotropin-releasing factor (CRF)-treated rats had decreased plasma testosterone levels. The subcutaneous administration of 0.075 or 0.75 nmol oCRF/h to intact rats for 7 d also resulted in elevations of both plasma ACTH and corticosterone levels comparable to those measured after a 24-h exposure to the releasing factor, as well as dose-related hypertrophy of the adrenals and increases in pituitary ACTH content. In these animals, CRF markedly inhibited luteinizing hormone (LH) (but not follicle-stimulating hormone [FSH] ), testosterone, and PRL secretion and decreased seminal vesicle weights. All the effects of CRF were mimicked by exogenously administered ACTH. By contrast, with the exception of FSH secretion, which was slightly elevated by CRF, neither CRF nor ACTH were able to significantly modify reproductive parameters in adrenalectomized animals, which suggests that the elevation of circulating levels of adrenal steroids induced by peripherally administered CRF represents major mediators of CRF-induced inhibition of fertility. These results indicate that in the rat, the continuous stimulation of the pituitary-adrenal axis by peripherally administered CRF causes some degree of desensitization of the pituitary-adrenal axis, but is still accompanied by persistent elevations of the circulating levels of both ACTH and corticosteroids. The increased secretion of adrenal steroids by CRF-treated rats is believed to participate in the disruption of reproductive parameters observed in these rats.
Collapse
|
50
|
Spindler-Vomachka M, Johnson DC. Altered hypothalamic-pituitary function in the adult female rat with streptozotocin-induced diabetes. Diabetologia 1985; 28:38-44. [PMID: 3920097 DOI: 10.1007/bf00276998] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Infertility associated with anovulation and loss of regular oestrous cyclicity is a consequence of diabetes mellitus in the rat. In an attempt to define loci of altered function, studies were undertaken to examine various aspects of hypothalamic-pituitary function in rats treated with streptozotocin. Medial basal hypothalamic fragments from adult female diabetic rats contained the same amount of gonadotrophin-releasing hormone but, with depolarization, released slightly but insignificantly (p greater than 0.05) more than did those from control animals. Furthermore, release of luteinizing hormone from pituitaries exposed to hypothalamic gonadotrophin-releasing hormone was not altered by diabetes. Removal of the negative feedback effect of gonadal steroids upon the hypothalamic-pituitary axis produced an increase in luteinizing hormone and follicle stimulating hormone concentrations in the serum of normal rats within 6h (p less than 0.05), whereas 24h were required for similar increases in diabetic rats. However, the same concentrations of gonadotrophins were found in diabetic and control animals 120 h after ovariectomy. The inhibitory action of oestradiol benzoate on the secretion of gonadotrophins was more pronounced in ovariectomized diabetic than in control rats. A 74% depression in serum luteinizing hormone (p less than 0.01) was produced by 0.5 microgram oestradiol benzoate per day in diabetic rats, while 5 micrograms was required in control animals. Similar reductions in follicle stimulating hormone concentrations (50%, p less than 0.05) were obtained by injecting 5 micrograms of the oestrogen into diabetic or 50 micrograms into control rats. Increases in serum prolactin were greater in the control animals however.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
|