1
|
Finol HJ, Garcia-Lunardi E, González R, Girón ME, Uzcátegui NL, Rodríguez-Acosta A. Qualitative and Quantitative Study of the Changes in the Ultrastructure of Mammalian Adrenal Cortex Caused by the Venezuelan Tigra Mariposa ( Bothrops venezuelensis) Snake Venom. J Microsc Ultrastruct 2020; 8:104-114. [PMID: 33282685 PMCID: PMC7703017 DOI: 10.4103/jmau.jmau_49_19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Accepted: 05/09/2020] [Indexed: 12/03/2022] Open
Abstract
The damage of the adrenal gland by snake venoms needs to be clarified. Lethality (LD50) of Bothrops venezuelensis (Bv) venom was established by intraperitoneally mice injections. Preparation of specimens for transmission electron microscopy samples from cortex adrenal gland biopsies at 3, 6, and 24 h was processed. The quantitative description by the principal component analysis (PCA) of the adrenal gland was as follows: thickening of the capillary endothelium, area of the capillary lumen, cell nucleus area, enlargement of the perinuclear space, number of mitochondria, area of the mitochondria, number of mitochondrial cristae, number of cristae per mitochondrial unit, and tubular diameter of the smooth endoplasmic reticulum (SER). Sections of the adrenal cortex, after 3 h postinjection with Bv venom showed in the cortical cells: mitochondria with tubular cristae and slightly swollen SER cisternae, nucleus with variable heterochromatin content, irregular edges, and swollen nuclear envelope. After 6 h, cells with swollen nucleus envelope, electron dense lipids and mitochondria with loss of their cristae were observed. Myelin figures, close to the microvilli of the cortical cell, multivesicular bodies, swollen profiles of the SER, and electron dense lipid drops were noticed. After 24 h, thickening of the endothelial wall, fenestrae and projections into the capillary lumen, loss of the mitochondrial cristae, destruction of the capillary and the plasma membrane of the cortical cell, multivesicular body, SER loss, and an enlargement of the perinuclear space were detected. In the quantitative PCA, there were significant changes after the venom treatments.
Collapse
Affiliation(s)
- Héctor J Finol
- Microscopy Electronic Centre, Faculty of Sciences, Universidad Central De Venezuela, Caracas, Venezuela
| | - Estefanie Garcia-Lunardi
- Microscopy Electronic Centre, Faculty of Sciences, Universidad Central De Venezuela, Caracas, Venezuela
| | - Roschman González
- Microscopy Electronic Centre, Faculty of Sciences, Universidad Central De Venezuela, Caracas, Venezuela
| | - Maria E Girón
- Anatomical Institute, Immunochemistry and Ultrastructure Laboratory, Universidad Central De Venezuela, Caracas, Venezuela
| | - Nestor L Uzcátegui
- Anatomical Institute, Immunochemistry and Ultrastructure Laboratory, Universidad Central De Venezuela, Caracas, Venezuela
| | - Alexis Rodríguez-Acosta
- Anatomical Institute, Immunochemistry and Ultrastructure Laboratory, Universidad Central De Venezuela, Caracas, Venezuela
| |
Collapse
|
2
|
Dobson H, Routly JE, Smith RF. Understanding the trade-off between the environment and fertility in cows and ewes. Anim Reprod 2020; 17:e20200017. [PMID: 33029210 PMCID: PMC7534569 DOI: 10.1590/1984-3143-ar2020-0017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The environment contributes to production diseases that in turn badly affect cow performance, fertility and culling. Oestrus intensity is lower in lame cows, and in all cows 26% potential oestrus events are not expressed (to avoid getting pregnant). To understand these trade-offs, we need to know how animals react to their environment and how the environment influences hypothalamus-pituitary-adrenal axis (HPA) interactions with the hypothalamus-pituitary-ovarian axis (HPO). Neurotransmitters control secretion of GnRH into hypophyseal portal blood. GnRH/LH pulse amplitude and frequency drive oestradiol production, culminating in oestrus behaviour and a precisely-timed GnRH/LH surge, all of which are disrupted by poor environments. Responses to peripheral neuronal agents give clues about mechanisms, but do these drugs alter perception of stimuli, or suppress consequent responses? In vitro studies confirm some neuronal interactions between the HPA and HPO; and immuno-histochemistry clarifies the location and sequence of inter-neurone activity within the brain. In both species, exogenous corticoids, ACTH and/or CRH act at the pituitary (reduce LH release by GnRH), and hypothalamus (lower GnRH pulse frequency and delay surge release). This requires inter-neurones as GnRH cells do not have receptors for HPA compounds. There are two (simultaneous, therefore fail-safe?) pathways for CRH suppression of GnRH release via CRH-Receptors: one being the regulation of kisspeptin/dynorphin and other cell types in the hypothalamus, and the other being the direct contact between CRH and GnRH cell terminals in the median eminence. When we domesticate animals, we must provide the best possible environment otherwise animals trade-off with lower production, less intense oestrus behaviour, and impaired fertility. Avoiding life-time peri-parturient problems by managing persistent lactations in cows may be a worthy trade-off on both welfare and economic terms – better than the camouflage use of drugs/hormones/feed additives/intricate technologies? In the long term, getting animals and environment in a more harmonious balance is the ultimate strategy.
Collapse
Affiliation(s)
- Hilary Dobson
- Institute of Veterinary Science, University of Liverpool, Leahurst Campus, Neston, England
| | - Jean Elsie Routly
- Institute of Veterinary Science, University of Liverpool, Leahurst Campus, Neston, England
| | - Robert Frank Smith
- Institute of Veterinary Science, University of Liverpool, Leahurst Campus, Neston, England
| |
Collapse
|
3
|
Sheil M, Polkinghorne A. Optimal Methods of Documenting Analgesic Efficacy in Neonatal Piglets Undergoing Castration. Animals (Basel) 2020; 10:E1450. [PMID: 32825055 PMCID: PMC7552769 DOI: 10.3390/ani10091450] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 08/10/2020] [Accepted: 08/13/2020] [Indexed: 01/20/2023] Open
Abstract
Analgesic products for piglet castration are critically needed. This requires extensive animal experimentation such as to meet regulatory-required proof of efficacy. At present, there are no validated methods of assessing pain in neonatal piglets. This poses challenges for investigators to optimize trial design and to meet ethical obligations to minimize the number of animals needed. Pain in neonatal piglets may be subtle, transient, and/or variably expressed and, in the absence of validated methods, investigators must rely on using a range of biochemical, physiological and behavioural variables, many of which appear to have very low (or unknown) sensitivity or specificity for documenting pain, or pain-relieving effects. A previous systematic review of this subject was hampered by the high degree of variability in the literature base both in terms of methods used to assess pain and pain mitigation, as well as in outcomes reported. In this setting we provide a narrative review to assist in determining the optimal methods currently available to detect piglet pain during castration and methods to mitigate castration-induced pain. In overview, the optimal outcome variables identified are nociceptive motor and vocal response scores during castration and quantitative sensory-threshold response testing and pain-associated behaviour scores following castration.
Collapse
Affiliation(s)
- Meredith Sheil
- Animal Ethics Pty. Ltd., Yarra Glen, VIC 3775, Australia
| | - Adam Polkinghorne
- Department of Microbiology and Infectious Diseases, NSW Health Pathology, Nepean Hospital, Penrith, NSW 2750, Australia;
- Faculty of Medicine and Health, Nepean Clinical School, The University of Sydney Medical School, University of Sydney, Penrith, NSW 2750, Australia
| |
Collapse
|
4
|
Hasiec M, Herman AP, Misztal T. Salsolinol: a potential modulator of the activity of the hypothalamic-pituitary-adrenal axis in nursing and postweaning sheep. Domest Anim Endocrinol 2015; 53:26-34. [PMID: 26057577 DOI: 10.1016/j.domaniend.2015.04.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 04/23/2015] [Accepted: 04/24/2015] [Indexed: 10/23/2022]
Abstract
The most well-known physiological action of salsolinol (1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline) is the stimulation of prolactin secretion, especially during lactation. In addition, our recent work demonstrated that salsolinol inhibits the stress-induced activity of the hypothalamic-pituitary-adrenal (HPA) axis in lactating sheep. Here, we investigated whether salsolinol regulates the basal activity of the HPA axis in lactating sheep and whether its inhibitory action on the stress-induced activity of the HPA axis is present during the postweaning period. The first experiment was performed during the fifth week of lactation, in which unstressed sheep received an intracerebroventricular infusion of an antagonistic analogue of salsolinol, 1-MeDIQ (1-methyl-3,4-dihydroisoquinoline). Simultaneously, the infundibular nucleus and/or median eminence was perfused using the push-pull method. Sheep that received 1-MeDIQ infusion showed significantly higher concentration of plasma ACTH during the second, third, and fourth hour (P < 0.001, P < 0.01, and P < 0.001, respectively) and cortisol during the third and fourth hour (P < 0.001 and P < 0.01, respectively) than did sheep that received control infusion. There was no significant difference in the mean perfusate corticotropin-releasing hormone concentration between the 1-MeDIQ and control treatments. In the second experiment, sheep received an intracerebroventricular infusion of salsolinol during the ninth week of lactation and 48 h after lamb weaning. A comparison between the control groups in the first and second experiments revealed that sheep after weaning (ninth week of lactation) had significantly higher mean ACTH (P < 0.001) and cortisol (P < 0.001) concentrations during the first 2 h of the experiment than the nursing females (fifth week of lactation) had. Salsolinol significantly reduced the increased concentrations of ACTH and cortisol (P < 0.01) in sheep after lamb weaning. However, there was no difference in the expression of proopiomelanocortin messenger RNA within the anterior pituitary between the control and salsolinol-treated groups. In conclusion, salsolinol regulates the basal activity of the HPA axis in lactating sheep. In addition, the HPA axis of postweaning females is more sensitive to stressors associated with the experimental procedures, and salsolinol attenuates ACTH and cortisol release in this phenomenon.
Collapse
Affiliation(s)
- M Hasiec
- Department of Endocrinology, The Kielanowski Institute of Animal Physiology and Nutrition of the Polish Academy of Sciences, 05-110 Jablonna, Poland
| | - A P Herman
- Laboratory of Molecular Biology, The Kielanowski Institute of Animal Physiology and Nutrition of the Polish Academy of Sciences, 05-110 Jablonna, Poland
| | - T Misztal
- Department of Endocrinology, The Kielanowski Institute of Animal Physiology and Nutrition of the Polish Academy of Sciences, 05-110 Jablonna, Poland.
| |
Collapse
|
5
|
Hasiec M, Tomaszewska-Zaremba D, Misztal T. Suckling and salsolinol attenuate responsiveness of the hypothalamic-pituitary-adrenal axis to stress: focus on catecholamines, corticotrophin-releasing hormone, adrenocorticotrophic hormone, cortisol and prolactin secretion in lactating sheep. J Neuroendocrinol 2014; 26:844-52. [PMID: 25205344 DOI: 10.1111/jne.12222] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 04/12/2014] [Accepted: 08/30/2014] [Indexed: 01/01/2023]
Abstract
In mammals, the responsiveness of the hypothalamic-pituitary-adrenal (HPA) axis to stress is reduced during lactation and this mainly results from suckling by the offspring. The suckling stimulus causes a release of the hypothalamic 1-metyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (salsolinol) (a derivative of dopamine), one of the prolactin-releasing factors. To investigate the involvement of salsolinol in the mechanism suppressing stress-induced HPA axis activity, we conducted a series of experiments on lactating sheep, in which they were treated with two kinds of isolation stress (isolation from the flock with lamb present or absent), combined with suckling and/or i.c.v infusion of salsolinol and 1-methyl-3,4-dihydro-isoqinoline (1-MeDIQ; an antagonistic analogue of salsolinol). Additionally, a push-pull perfusion of the infundibular nucleus/median eminence (IN/ME) and blood sample collection with 10-min intervals were performed during the experiments. Concentrations of perfusate corticotrophin-releasing hormone (CRH) and catecholamines (noradrenaline, dopamine and salsolinol), as well as concentrations of plasma adenocorticotrophic hormone (ACTH), cortisol and prolactin, were assayed. A significant increase in perfusate noradrenaline, plasma ACTH and cortisol occurred in response to both kinds of isolation stress. Suckling and salsolinol reduced the stress-induced increase in plasma ACTH and cortisol concentrations. Salsolinol also significantly reduced the stress-induced noradrenaline and dopamine release within the IN/ME. Treatment with 1-MeDIQ under the stress conditions significantly diminished the salsolinol concentration and increased CRH and cortisol concentrations. Stress and salsolinol did not increase the plasma prolactin concentration, in contrast to the suckling stimulus. In conclusion, salsolinol released in nursing sheep may have a suppressing effect on stress-induced HPA axis activity and peripheral prolactin does not appear to participate in its action.
Collapse
Affiliation(s)
- M Hasiec
- Department of Endocrinology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Jablonna, Poland
| | | | | |
Collapse
|
6
|
Ghuman SPS, Morris R, Scherzer J, Routly JE, Mobasheri A, Smith RF, Dobson H. Neuronal Responses in the Brainstem and Hypothalamic Nuclei Following Insulin Treatment During the Late Follicular Phase in the Ewe. Reprod Domest Anim 2011; 46:121-9. [DOI: 10.1111/j.1439-0531.2010.01605.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
7
|
Ghuman SPS, Morris R, Spiller DG, Smith RF, Dobson H. Integration Between Different Hypothalamic Nuclei Involved in Stress and GnRH Secretion in the Ewe. Reprod Domest Anim 2009; 45:1065-73. [DOI: 10.1111/j.1439-0531.2009.01496.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
8
|
Ghuman SPS, Prabhakar S, Smith RF, Dobson H. Noradrenergic Control of Arginine Vasopressin Release from the Ewe Hypothalamus In Vitro: Sensitivity to Oestradiol. Reprod Domest Anim 2008; 43:137-43. [DOI: 10.1111/j.1439-0531.2007.00863.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
9
|
Avraham Y, Hao S, Mendelson S, Berry EM. Hypothalamic-pituitary-adrenal responses to weight loss in mice following diet restriction, activity or separation stress: effects of tyrosine. Nutr Neurosci 2002; 5:327-35. [PMID: 12385595 DOI: 10.1080/1028415021000033794] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
We have studied three different types of weight-loss stress caused by Diet restriction, Activity or Separation, for their effects on the hypothalamic-pituitary axis in young female mice and their responses to tyrosine 100 mg/kg/day. Plasma was assayed for ACTH and glucocorticoid determinations, and brain catecholamine concentrations were measured by HPLC/ECD. A similar weight loss of 24-28% was observed in the models despite significant differences in food intake. Diet restriction to 60% and Separation models produced a significant increase in hypothalamic noradrenaline (p < 0.01), while there was a significant decrease (p < 0.05) in the Diet restriction to 40% that was restored after tyrosine. After Activity, noradrenaline levels did not change. ACTH concentrations decreased following Diet restriction (p < 0.05) but were unaffected by Separation or Activity. The peripheral glucocorticoid response increased significantly after Activity and Diet restriction (p < 0.001), but decreased significantly after Separation (p < 0.001). Tyrosine increased glucocorticoid concentrations in the Activity and Separation models (p < 0.05), but not after Diet restriction. Despite similar weight loss in the three models there were no predictable associations between hypothalamic noradrenaline metabolism and plasma ACTH or glucocorticoid concentrations. Tyrosine might alleviate some of the different pathophysiological problems associated with the stress of weight loss.
Collapse
Affiliation(s)
- Yosefa Avraham
- Department of Human Nutrition and Metabolism, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | | | | | | |
Collapse
|
10
|
Russell SH, Small CJ, Dakin CL, Abbott CR, Morgan DG, Ghatei MA, Bloom SR. The central effects of orexin-A in the hypothalamic-pituitary-adrenal axis in vivo and in vitro in male rats. J Neuroendocrinol 2001; 13:561-6. [PMID: 11412343 DOI: 10.1046/j.1365-2826.2001.00672.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Orexin-A is synthesized in the posterolateral hypothalamus and immunoreactive fibres project to many central nervous system structures, including the paraventricular nucleus, which is rich in corticotropin releasing factor (CRF) neurones and neuropeptide Y (NPY) innervation. We investigated the central effects of orexin-A on the hypothalamic-pituitary-adrenal (HPA) axis by measuring plasma concentrations of corticosterone and adrenocorticotropic hormone (ACTH) in vivo. We explored the potential neuropeptide pathways involved by investigating the effects of orexin-A on CRF, NPY, arginine vasopressin (AVP) and noradrenaline release from hypothalamic explants in vitro. Intracerebroventricular (i.c.v.) injection of orexin-A (3 nmol) in male rats stimulated increases in plasma concentrations of corticosterone between 10 and 40 min after injection, and of plasma ACTH at 20 and 90 min after injection. Orexin-A significantly stimulated CRF and NPY release from hypothalamic explants in vitro. Orexin-A did not stimulate CRF release in the presence of the selective NPY Y1 receptor antagonist, BIBP3226. BIBP3226 alone did not alter CRF release from hypothalamic explants. Orexin-A had no effect in vitro on the release of other neuropeptides, AVP and noradrenaline, involved in the central regulation of the HPA axis. These results suggest that orexin-A is involved in activation of the HPA axis, and that these effects could be mediated via the release of NPY.
Collapse
Affiliation(s)
- S H Russell
- ICSM Endocrine Unit, ICSM, Hammersmith Hospital, Du Cane Road, London W12 ONN, UK
| | | | | | | | | | | | | |
Collapse
|
11
|
Abstract
Studies examining regulation of corticotropin-releasing hormone (CRH) in vitro have been used to validate findings obtained in vivo and more importantly have been used as model systems to better understand signalling mechanisms responsible for the expression of the CRH gene and peptide. Most in vitro studies examining CRH have utilized hypothalamic tissue while a few have focused on the amygdala. Furthermore, clonal cell lines have also been utilized as models of central nervous system CRH neurons. Stimuli that have been implicated in regulating hypothalamic CRH in vitro include protein kinase A (PKA) and protein kinase C (PKC) activators, glucocorticoids, biogenic amines, cytokines and the gaseous neurotransmitters. CRH levels in the amygdala in vitro are affected by some of the same stimuli that regulate hypothalamic CRH; however there is evidence supporting differential regulation of CRH in these two brain regions by some of the same stimuli. Only a few studies in aggregate have investigated the signal transduction mechanisms responsible for CRH expression. These mechanistic studies have focused on PKA- and glucocorticoid-mediated changes in CRH expression. Clearly much more investigative work in better understanding CRH regulation in vitro is needed.
Collapse
Affiliation(s)
- M Pisarska
- Cincinnati VAMC, Psychiatry Service, 3200 Vine Street, Cincinnati, OH 45220, USA
| | | | | | | | | |
Collapse
|
12
|
Engler D, Redei E, Kola I. The corticotropin-release inhibitory factor hypothesis: a review of the evidence for the existence of inhibitory as well as stimulatory hypophysiotropic regulation of adrenocorticotropin secretion and biosynthesis. Endocr Rev 1999; 20:460-500. [PMID: 10453355 DOI: 10.1210/edrv.20.4.0376] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- D Engler
- Laboratory of Molecular Genetics and Development, Institute of Reproduction and Development, Monash Medical Centre, Clayton, Victoria, Australia
| | | | | |
Collapse
|
13
|
Thun R, Kaufmann C, Janett F. The Influence of Restraint Stress on Reproductive Hormones in the Cow. Reprod Domest Anim 1998. [DOI: 10.1111/j.1439-0531.1998.tb01354.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
14
|
Abraham EJ, Minton JE. Effects of corticotropin-releasing hormone, lysine vasopressin, oxytocin, and angiotensin II on adrenocorticotropin secretion from porcine anterior pituitary cells. Domest Anim Endocrinol 1996; 13:259-68. [PMID: 8738867 DOI: 10.1016/0739-7240(96)00015-x] [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: 02/01/2023]
Abstract
The aim of this study was to determine the ability of corticotropin-releasing hormone (CRH), lysine vasopressin (LVP), oxytocin (OT), and angiotensin II (AII) to stimulate adrenocorticotropin (ACTH) secretion from porcine anterior pituitary (AP) cells in vitro and to evaluate the role of protein kinase C (PKC) in the interaction between CRH and LVP. In this study, porcine AP cells were enzymatically and mechanically dispersed, cultured (150,000 cells/well) for 4 d, and then challenged with doses of various neuropeptides for 3 hr. CRH (10(-7)-10(-10) M) was the most potent of the peptides tested in stimulating ACTH release from porcine AP cells. In fact, none of the other peptides consistently affected ACTH concentrations relative to basal levels. However, LVP potentiated CRH action, even though by itself, it failed to stimulate ACTH production. Neither OT or AII potentiated CRH-stimulated ACTH release from porcine AP cells. To determine whether the inter-action between CRH and LVP was regulated partially by the protein Kinase C (PKC) pathway, we challenged AP cells in a 30-min incubation with 10(-7) M staurosporine (ST), a treatment predicted to decrease PKC activity. Then, cells were washed and challenged with 10(-9) M LVP, 10(-9) M CRH, and 10(-9) M CRH + LVP. Treatment with ST decreased (P < 0.05) CRH + LVP-stimulated ACTH release. To further demonstrate an interaction between protein kinase A (PKA) and PKC transduction pathways in the observed synergism between CRH and LVP to enhance ACTH secretion, we also challenged AP cells with 10(-7) M phorbol 12, 13-myristate acetate (PMA) and 5 microM forskolin (FOR) for 3 hr. This treatment was predicted to enhance PKA and PKC activities, respectively, and thereby enhance ACTH concentrations. Challenging cells with FOR + PMA enhanced (P < 0.001) ACTH release above basal concentrations, but more important, it increased (P < 0.001) ACTH concentration above that elicited by either drug given alone. Taken together, our in vitro studies support the conclusion that CRH is the principal regulator of ACTH secretion in the pig. In contrast to the results in most other species evaluated, vasopressin alone did not affect ACTH release. However, LVP can enhance the effectiveness of CRH in releasing ACTH, and this enhancement appears to rely, at least in part, on the activation of the PKC signal transduction pathway.
Collapse
Affiliation(s)
- E J Abraham
- Department of Animal Sciences and Industry, Kansas State University Manhattan 66506-0201, USA
| | | |
Collapse
|
15
|
Abstract
Male Wistar rats were injected with CH-38083, an alpha 2-adrenoceptor blocker, after which they were challenged by a size-matched Wistar or Long-Evans opponent. In residents facing low-aggression opponents, the alpha 2-adrenoceptor blockade significantly reduced aggressiveness, whereas in those facing highly aggressive opponents the treatment significantly increased aggression scores compared to saline-treated controls, irrespective of the strain of the intruder. When the animals were treated with CH-38083, the frequency of biting attacks correlated significantly with the aggressiveness of the opponent in residents fighting with Wistar and Long-Evans rats. Similar correlations were not found in control (saline-injected) rats. The results suggest that the catecholaminergic activation caused by the alpha 2 receptor antagonist elicits a more efficient adaptation to the behavioral actions of the opponent. Plasma corticosterone levels were not influenced by the treatment, but this variable seemed to be correlated with the defensive behavior performed by the intruder.
Collapse
Affiliation(s)
- J Haller
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest
| |
Collapse
|
16
|
Engler D, Liu JP, Clarke IJ, Funder JW. Corticotropin-release inhibitory factor Evidence for dual stimulatory and inhibitory hypothalamic regulation over adrenocorticotropin secretion and biosynthesis. Trends Endocrinol Metab 1994; 5:272-83. [PMID: 18407219 DOI: 10.1016/1043-2760(94)p3202-i] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The hypothalamus is currently thought to stimulate the synthesis and secretion of ACTH uniquely by secreting neuropeptides into the hypophysial-portal circulation, of which the most important are CRH and arginine vasopressin. However, analysis of the effects of pituitary isolation on the pituitary-adrenal axis in a variety of species suggests that the hypothalamus exerts both stimulatory and inhibitory regulation over ACTH secretion and POMC biosynthesis, and that the inhibitory control is dominant. Because none of the currently known inhibitory factors in the hypophysial-portal circulation consistently decreases basal ACTH secretion and POMC mRNA levels in normal anterior pituitary cells, it is suggested that this inhibition is mediated by a currently unidentified hypothalamic substance, presumably a neuropeptide, which we have termed corticotropin-release inhibitory factor (CRIF). The possible roles in clinical medicine of agonists and antagonists of this putative CRIF are discussed.
Collapse
Affiliation(s)
- D Engler
- Prince Henry's Institute of Medical Research and the Molecular Embryology and Birth Defects Laboratory, Monash Medical Centre, Clayton, Victoria 3168, Australia
| | | | | | | |
Collapse
|
17
|
Haller J, Barna I, Kovács JL. Alpha 2-adrenoceptor blockade, pituitary-adrenal hormones, and agonistic interactions in rats. Psychopharmacology (Berl) 1994; 115:478-84. [PMID: 7871092 DOI: 10.1007/bf02245571] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The effects of adrenergic activation on aggressiveness and the aggression induced endocrine changes were tested in rats. Alpha 2 adrenoceptor blockers were used for enhancing activation of the adrenergic system, and changes in aggressiveness were tested in resident-intruder contests. Three experiments were conducted. In experiment 1, saline injected rats responded to the presence of an opponent by aggression and the increase in plasma ACTH and corticosterone. Intraperitoneal administration of 1 mg/kg CH-38083 (an alpha 2 adrenoceptor antagonist) produced a several fold increase in clinch fighting and mutual upright scores, and also further enhanced the plasma ACTH and corticosterone response. In experiment 2, the effect of three doses (0.5, 1 and 2 mg/kg) of three different alpha 2 adrenoceptor blockers CH-38083, idazoxan and yohimbine were tested. All the substances increased aggression at 0.5 and 1 mg/kg; at 2 mg/kg the effect of idazoxan and yohimbine disappeared, while with CH-38083 an additional increase was obtained. In yohimbine treated animals the enhancement of aggression was reduced already at 1 mg/kg. In experiment 3, indomethacin, a potent inhibitor of the catecholamine-induced ACTH release completely abolished the effects of the alpha 2 adrenoceptor antagonist CH-38083: the intensity of agonistic interactions, as well as ACTH and corticosterone plasma concentrations, returned to control levels. The possible role of catecholamines and the stress hormones in the activation of aggression is discussed.
Collapse
Affiliation(s)
- J Haller
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest
| | | | | |
Collapse
|
18
|
Liu JP, Clarke IJ, Funder JW, Engler D. Studies of the secretion of corticotropin-releasing factor and arginine vasopressin into the hypophysial-portal circulation of the conscious sheep. II. The central noradrenergic and neuropeptide Y pathways cause immediate and prolonged hypothalamic-pituitary-adrenal activation. Potential involvement in the pseudo-Cushing's syndrome of endogenous depression and anorexia nervosa. J Clin Invest 1994; 93:1439-50. [PMID: 8163648 PMCID: PMC294157 DOI: 10.1172/jci117121] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Studies were performed to determine the effects of intracerebroventricular norepinephrine (NE) or neuropeptide Y (NPY) on the ovine hypothalamic-pituitary-adrenal (HPA) axis. NE (50 micrograms) increased mean hypophysial-portal corticotropin-releasing factor (CRF) and arginine vasopressin (AVP) levels (1 h, 1.3- and 2.9-fold; 4 h, 2.2- and 5.7-fold) and caused acute and sustained increases in mean plasma ACTH and cortisol. NPY (50 microgram) also increased mean CRF and AVP levels (1 h, 1.4- and 4.2-fold; 4 h, 1.1- and 1.9-fold), increased pituitary-adrenal activity at 1 h, and caused ACTH hypersecretion at 4 h. When added to cultured ovine anterior pituitary cells, NPY neither increased basal ACTH release nor augmented CRF- or AVP-induced ACTH release. We conclude that: (a) activation of either the central noradrenergic or NPY pathways causes an acute and sustained stimulation of the ovine HPA axis; (b) such activation increases the AVP/CRF ratio, suggesting a dominant role for AVP in the ovine stress response; and (c) the central noradrenergic or NPY systems may cause sustained HPA activation by attenuating or disrupting the glucocorticoid negative feedback on those brain areas concerned with regulation of the HPA axis. The possible roles of the central noradrenergic and NPY systems in the etiology of the hypercortisolemia of endogenous depression and anorexia nervosa are discussed.
Collapse
Affiliation(s)
- J P Liu
- Prince Henry's Institute of Medical Research, Clayton, Victoria, Australia
| | | | | | | |
Collapse
|
19
|
Martinez-Piñero MG, Milanes MV, Vargas ML. Modulation by catecholamine of hypothalamus-pituitary-adrenocortical (HPA) axis activity in morphine-tolerance and withdrawal. GENERAL PHARMACOLOGY 1994; 25:187-92. [PMID: 8026704 DOI: 10.1016/0306-3623(94)90031-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
1. Hypothalamic noradrenaline (NA), dopamine (DA) and plasma corticosterone concentrations were determined after acute morphine administration to both naive and morphine-tolerant rats and during naloxone-induced withdrawal. 2. Acutely administered morphine (30 mg/kg) significantly increased the plasma level of corticosterone and reduced the NA and DA content in the hypothalamus. Naloxone (1 mg/kg), administered before morphine, blocked the effect of the opiate on both plasma corticosterone and hypothalamic NA concentration. 3. In chronically morphine-treated rats, a challenge dose of morphine (30 mg/kg) neither modified the plasma corticosterone level nor the NA concentration, while DA content was significantly enhanced. 4. After naloxone-induced withdrawal, the hypothalamic content of NA was significantly reduced, simultaneously with an increase in plasma corticosterone, while DA content remained unchanged. 5. These results suggest that the hypothalamic noradrenergic neurons are mainly mainly implicated in the effect of acute morphine on the hypothalamus-pituitary-adrenocortical (HPA) axis and in the tolerance development to this effect. The results also suggest that a hyperactivity of noradrenergic pathways in the hypothalamus would be one of the physiologically relevant mechanisms mediating the neuroendocrine opiate withdrawal at the HPA level.
Collapse
Affiliation(s)
- M G Martinez-Piñero
- Department of Physiology and Pharmacology, University School of Medicine, Murcia, Spain
| | | | | |
Collapse
|
20
|
Whitnall MH. Regulation of the hypothalamic corticotropin-releasing hormone neurosecretory system. Prog Neurobiol 1993; 40:573-629. [PMID: 8484004 DOI: 10.1016/0301-0082(93)90035-q] [Citation(s) in RCA: 452] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- M H Whitnall
- Department of Physiology, Armed Forces Radiobiology Research Institute, Bethesda, MD 20889-5145
| |
Collapse
|
21
|
Engler D. Evidence that the hypothalamus exerts both stimulatory and inhibitory influences over adrenocorticotropin secretion and biosynthesis in the sheep. REGULATORY PEPTIDES 1993; 45:171-82. [PMID: 8390077 DOI: 10.1016/0167-0115(93)90202-j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- D Engler
- Prince Henry's Institute of Medical Research, Clayton, Victoria, Australia
| |
Collapse
|
22
|
Apostolakis EM, Rice KE, Longo LD, Seron-Ferre M, Yellon SM. Time of day of birth and absence of endocrine and uterine contractile activity rhythms in sheep. THE AMERICAN JOURNAL OF PHYSIOLOGY 1993; 264:E534-40. [PMID: 8476031 DOI: 10.1152/ajpendo.1993.264.4.e534] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
To determine whether 24-h rhythms characterize hormone secretion and uterine activity in the pregnant sheep, blood samples were drawn every 1-4 h for 48 h from ewes and fetuses from day 120 of gestation to term. Repetitive 24-h rhythms were absent for cortisol, progesterone, and prolactin in maternal and fetal circulation and for hourly mean uterine contraction rate and amplitude. To test whether photoperiod or pineal melatonin contributes to the absence of rhythms, pineal-intact and pinealectomized ewes and their fetuses were studied in reverse photoperiod. Again, there was little evidence to suggest 24-h endocrine rhythms except for prolactin in two fetuses by cosinor analyses. Prolactin concentrations were increased in pinealectomized ewes and their fetuses. In the apparent absence of rhythms, 20 of 21 pineal-intact ewes gave birth at night; however, 6 out of 7 pinealectomized ewes gave birth during the day. Thus photoperiod and the maternal pineal gland profoundly influenced the time of day of birth in the absence of circadian endocrine or uterine activity rhythms.
Collapse
Affiliation(s)
- E M Apostolakis
- Department of Physiology, School of Medicine, Loma Linda University, California 92350
| | | | | | | | | |
Collapse
|