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Wingfield JC. Coping with change: a framework for environmental signals and how neuroendocrine pathways might respond. Front Neuroendocrinol 2015; 37:89-96. [PMID: 25511258 DOI: 10.1016/j.yfrne.2014.11.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 11/20/2014] [Accepted: 11/21/2014] [Indexed: 12/11/2022]
Abstract
The Earth has always been a changeable place but now warming trends shift seasons and storms occur with greater frequency, intensity and duration. This has prompted reference to the modern era as the Anthropocene caused by human activity. This era poses great challenges for all life on earth and important questions include why and how some organisms can cope and others cannot? It is of heuristic value to consider a framework for types of environmental signals and how they might act. This is especially important as predictable changes of the environment (seasonality) are shifting rapidly as well as unpredictable changes (perturbations) in novel ways. What we need to know is how organisms perceive their environment, transduce that information into neuroendocrine signals that orchestrate morphological, physiological and behavioral responses. Given these goals we can begin to address the questions: do neuroendocrine systems have sufficient flexibility to acclimate to significant change in phenology, are genetic changes leading to adaptation necessary, or both?
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Affiliation(s)
- John C Wingfield
- Department of Neurobiology, Physiology and Behavior, University of California, One Shields Avenue, Davis, CA 95616, USA.
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McClusky LM. Coordination of spermatogenic processes in the testis: lessons from cystic spermatogenesis. Cell Tissue Res 2013; 349:703-15. [PMID: 22314845 DOI: 10.1007/s00441-011-1288-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2011] [Accepted: 11/11/2011] [Indexed: 12/21/2022]
Abstract
A common observation in the vertebrate testis is that new germ cell clones enter spermatogenesis proper before previously formed clones have completed their development. The extent to which the developmental advance of any given germ cell clone in any phase of spermatogenesis is dependent on that of neighboring clones and/or on the coordinating influence of associated Sertoli cells in the immediate vicinity or of others further away remains unclear. This review presents an overall synthesis of findings in an ancient vertebrate, the spiny dogfish shark and shows that, even at this phyletic level, the developmental advance of a given germ cell clone is the outcome of various processes emanating from its spatiotemporal relationship with (1) its own complement of Sertoli cells in the anatomically distinct spermatocyst and (2) Sertoli cells associated with other germ cell clones that lie upstream or downstream in the spermatogenic progression and that secrete, among others, androgen and estrogen destined for target sites upstream. Analysis of the protracted spermatogenic cycle shows the coordination in space and time of spermatogenic and steroidogenic events. Furthermore, the natural withdrawal of pituitary gonadotropin support in the dogfish causes a distinct and highly ordered gradient of apoptosis among the spermatogonial generations; this in turn is a major contributing factor to the cyclic nature of sperm production observed in this lower vertebrate. Because of the simplicity of their testicular organization, their cystic spermatogenesis and their phylogenetic position, cartilaginous fishes constitute a valid vertebrate reference system for comparative analysis with higher vertebrates.
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Wang DH, Hu JR, Wang LY, Hu YJ, Tan FQ, Zhou H, Shao JZ, Yang WX. The apoptotic function analysis of p53, Apaf1, Caspase3 and Caspase7 during the spermatogenesis of the Chinese fire-bellied newt Cynops orientalis. PLoS One 2012; 7:e39920. [PMID: 22768170 PMCID: PMC3386923 DOI: 10.1371/journal.pone.0039920] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 05/29/2012] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Spontaneous and stress-induced germ cell apoptosis during spermatogenesis of multicellular organisms have been investigated broadly in mammals. Spermatogenetic process in urodele amphibians was essentially like that in mammals in spite of morphological differences; however, the mechanism of germ cell apoptosis in urodele amphibians remains unknown. The Chinese fire-belly newt, Cynops orientalis, was an excellent organism for studying germ cell apoptosis due to its sensitiveness to temperature, strong endurance of starvation, and sensitive skin to heavy metal exposure. METHODOLOGY/PRINCIPAL FINDINGS TUNEL result showed that spontaneous germ cell apoptosis took place in normal newt, and severe stress-induced apoptosis occurred to spermatids and sperm in response to heat shock (40°C 2 h), cold exposure (4°C 12 h), cadmium exposure (Cd 36 h), and starvation stress. Quantitative reverse transcription polymerase chain reactions (qRT-PCR) showed that gene expression of Caspase3 or Caspase7 was obviously elevated after stress treatment. Apaf1 was not altered at its gene expression level, and p53 was significantly decreased after various stress treatment. Caspase assay demonstrated that Caspase-3, -8, -9 enzyme activities in newt testis were significantly elevated after heat shock (40°C 2 h), cold exposure (4°C 12 h), and cadmium exposure (Cd 36 h), while Caspase3 and Caspase8 activities were increased with Caspase9 significantly decreased after starvation treatment. CONCLUSIONS/SIGNIFICANCE Severe germ cell apoptosis triggered by heat shock, cold exposure, and cadmium exposure was Caspase3 dependent, which probably involved both extrinsic and intrinsic pathways. Apaf1 may be involved in this process without elevating its gene expression. But starvation-induced germ cell apoptosis was likely mainly through extrinsic pathway. p53 was probably not responsible for stress-induced germ cell apoptosis in newt testis. The intriguing high occurrence of spermatid and sperm apoptosis probably resulted from the sperm morphology and unique reproduction policy of Chinese fire-belly newt, Cynops orientalis.
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Affiliation(s)
- Da-Hui Wang
- The Sperm Laboratory, College of Life Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Jian-Rao Hu
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, People's Republic of China
| | - Li-Ya Wang
- Department of Reproductive Endocrinology, The Women’s Hospital, School of Medicine, Zhejiang University, Hangzhou, People's Republic of China
| | - Yan-Jun Hu
- Department of Reproductive Endocrinology, The Women’s Hospital, School of Medicine, Zhejiang University, Hangzhou, People's Republic of China
| | - Fu-Qing Tan
- The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, People's Republic of China
| | - Hong Zhou
- The Sperm Laboratory, College of Life Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Jian-Zhong Shao
- The Sperm Laboratory, College of Life Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Wan-Xi Yang
- The Sperm Laboratory, College of Life Sciences, Zhejiang University, Hangzhou, People's Republic of China
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Volonteri MC, Ceballos NR. Mechanism of hCG-induced spermiation in the toad Rhinella arenarum (Amphibia, Anura). Gen Comp Endocrinol 2010; 169:197-202. [PMID: 20800063 DOI: 10.1016/j.ygcen.2010.08.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Revised: 07/28/2010] [Accepted: 08/20/2010] [Indexed: 01/15/2023]
Abstract
In Rhinella arenarum spermiation occurs as a consequence of LH/FSH increase during the amplexus or by a single dose of hCG, among other gonadotropins. The present study employs an in vitro system to study the mechanism of action of hCG in the spermiation of R. arenarum. Testicular fragments were incubated for 2h at 28°C in the presence or absence of 20IU hCG with or without different PKA/PKC inhibitors and activators as well as ouabain and amiloride as Na(+)/K(+) ATPase and transcellular Na(+) transport inhibitors, respectively. Ouabain did not induce spermiation in absence of hCG and inhibited hCG-induced spermiation in a dose-dependent manner, reaching 90% inhibition with the higher concentration. In contrast, amiloride neither affected spermiation nor steroidogenesis. Activation of PKA with 8Br-cAMP induced spermiation in the absence of hCG while its inhibition with H89 blocked hCG action. On the other hand, PKC inhibition with Bi or STP did not affect hCG-induced spermiation although PKC activation significantly decreased hCG-dependent sperm release. These results suggest that PKC inhibits spermiation but also that the inhibition exerted by the kinase could be blocked by hCG. Taken together, these observations could indicate that PKA is involved in the mechanism of the gonadotropin action, mechanism also requiring the activation of a non-pumping Na(+)/K(+) ATPase pathway.
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Affiliation(s)
- M Clara Volonteri
- Laboratorio de Endocrinología Comparada, Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
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Gay F, Laforgia V, Capaldo A. Human follicle-stimulating hormone modulation of adrenal gland activity in the Italian crested newt, Triturus carnifex (Amphibia, Urodela). Comp Biochem Physiol A Mol Integr Physiol 2008; 151:126-32. [DOI: 10.1016/j.cbpa.2008.06.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2008] [Revised: 06/10/2008] [Accepted: 06/10/2008] [Indexed: 11/28/2022]
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Tsai PS, Kessler AE, Jones JT, Wahr KB. Alteration of the hypothalamic-pituitary-gonadal axis in estrogen- and androgen-treated adult male leopard frog, Rana pipiens. Reprod Biol Endocrinol 2005; 3:2. [PMID: 15642123 PMCID: PMC548137 DOI: 10.1186/1477-7827-3-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2004] [Accepted: 01/10/2005] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Gonadal steroids, in particular 5 alpha-dihydrotestosterone (DHT) and 17 beta-estradiol (E2), have been shown to feed back on the hypothalamic-pituitary-gonadal (HPG) axis of the ranid frog. However, questions still remain on how DHT and E2 impact two of the less-studied components of the ranid HPG axis, the hypothalamus and the gonad, and if the feedback effects are consistently negative. Thus, the goal of the study was to examine the effects of DHT and E2 upon the HPG axis of the gonadally-intact, sexually mature male leopard frogs, Rana pipiens. METHODS R. pipiens were implanted with silastic capsules containing either cholesterol (Ch, a control), DHT, or E2 for 10 or 30 days. At each time point, steroid-induced changes in hypothalamic GnRH and pituitary LH concentrations, circulating luteinizing hormone (LH), and testicular histology were examined. RESULTS Frogs implanted with DHT or E2 for 10 days did not show significant alterations in the HPG axis. In contrast, frogs implanted with hormones for 30 days had significantly lower circulating LH (for both DHT and E2), decreased pituitary LH concentration (for E2 only), and disrupted spermatogenesis (for both DHT and E2). The disruption of spermatogenesis was qualitatively similar between DHT and E2, although the effects of E2 were consistently more potent. In both DHT and E2-treated animals, a marked loss of all pre-meiotic germ cells was observed, although the loss of secondary spermatogonia appeared to be the primary cause of disrupted spermatogenesis. Unexpectedly, the presence of post-meiotic germ cells was either unaffected or enhanced by DHT or E2 treatment. CONCLUSIONS Overall, these results showed that both DHT and E2 inhibited circulating LH and disrupted spermatogenesis progressively in a time-dependent manner, with the longer duration of treatment producing the more pronounced effects. Further, the feedback effects exerted by both steroid hormones upon the HPG axis were largely negative, although the possibility exists for a stimulatory effect upon the post-meiotic germ cells.
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Affiliation(s)
- Pei-San Tsai
- Department of Integrative Physiology and the Center for Neuroscience, University of Colorado, Boulder, CO 80309-0354, USA
| | - Ann E Kessler
- Department of Integrative Physiology and the Center for Neuroscience, University of Colorado, Boulder, CO 80309-0354, USA
| | - Jeremy T Jones
- Department of Integrative Physiology and the Center for Neuroscience, University of Colorado, Boulder, CO 80309-0354, USA
| | - Kathleen B Wahr
- Department of Integrative Physiology and the Center for Neuroscience, University of Colorado, Boulder, CO 80309-0354, USA
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Pozzi AG, Rosemblit C, Ceballos NR. Effect of human gonadotropins on spermiation and androgen biosynthesis in the testis of the toadBufo arenarum (Amphibia, Anura). ACTA ACUST UNITED AC 2005; 305:96-102. [PMID: 16358275 DOI: 10.1002/jez.a.254] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
This paper analyzes, in the toad Bufo arenarum, the effect on spermiation and androgen secretion of two human recombinant gonadotropins, human recombinant LH (hrLH) and human recombinant FSH (hrFSH) as well as the well-known spermiation-inducing hormone, human chorionic gonadotropin (hCG). For this purpose, testes were incubated with different concentrations of hrLH (0.01-2.5 microg/ml) and hrFSH (0.05-5 microg/ml), and results were compared with those obtained with 2.5 microg/ml hCG. Spermiation was most efficiently stimulated by hrFSH, which elicited a higher response than either hrLH or hCG. Both hrFSH and hrLH produced a bell-shaped dose-response curve, with a 50% inhibition on spermiation at a concentration twice higher than that necessary to get the highest response. However, none of the gonadotropins yielded a biphasic response on androgen secretion, hrLH producing the highest response at a concentration that evoked a 70% inhibition in the spermiation test. Regarding steroidogenesis, hrLH and hrFSH were more active than hCG. Taken together, the results described in this paper suggest that, in B. arenarum, spermiation and androgen secretion are mediated by different receptors. After comparing the effects of recombinant hormones, we conclude that hrFSH has a greater effect on spermiation than hCG or hrLH.
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Affiliation(s)
- Andrea Gabriela Pozzi
- Laboratorio de Endocrinología Comparada and PRHOM-CONICET, Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, Argentina.
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Yazawa T, Nakayama Y, Fujimoto K, Matsuda Y, Abe K, Kitano T, Abé SI, Yamamoto T. Abnormal spermatogenesis at low temperatures in the Japanese red-bellied newt, Cynops pyrrhogaster: possible biological significance of the cessation of spermatocytogenesis. Mol Reprod Dev 2003; 66:60-6. [PMID: 12874800 DOI: 10.1002/mrd.10328] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In newt testis, spermatocytes never appear during winter, because secondary spermatogonia die by apoptosis just before meiosis. In the current study, we examined the effect of low temperatures on spermatogenesis. Incubation of newts at low temperatures (8, 12, 15 degrees C) induced defects in spermatogenesis in a temperature-dependent manner. At 8 degrees C, multinucleated giant cells (MGCs) were observed in spermatocytes and spermatogenesis never proceeded beyond meiosis. Although spermatocytes completed meiotic divisions at 12 degrees C, severe cell death was observed in the spermatids. At 15 degrees C both normal and abnormal spermiogenesis were observed. Under these conditions, impaired meiotic synapsis/recombination and down-regulation of the expression of the DMC1 protein, which play pivotal roles in meiotic pairing in eukaryotes, were also observed. Furthermore, to examine the quality of the sperm produced at low temperature for supporting development, artificial insemination was performed. The eggs inseminated with spermatozoa derived from newts kept at 15 degrees C demonstrated a restricted developmental capacity, even though these spermatozoa had an equal capacity for carrying out fertilization to those kept at 22 degrees C. These results suggest that meiosis at low temperatures cause the production of abnormal spermatozoa. Conservation and the significance of this phenomenon in poikilothermic vertebrates living in the temperate zones are also discussed.
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Affiliation(s)
- Takashi Yazawa
- Department of Biochemistry, Fukui Medical University, Shimoaizuki, Matsuoka, Fukui, Japan
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Abé K, Jin Y, Yamamoto T, Abé SI. Human recombinant stem cell factor promotes spermatogonial proliferation, but not meiosis initiation in organ culture of newt testis fragments. Biochem Biophys Res Commun 2002; 294:695-9. [PMID: 12056826 DOI: 10.1016/s0006-291x(02)00537-5] [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: 11/16/2022]
Abstract
We previously showed that mammalian FSH stimulates the proliferation of newt spermatogonia and induces their differentiation into primary spermatocytes in vitro. In the current study, to examine a possibility that stem cell factor (SCF) is involved in the proliferation of newt spermatogonia and/or their differentiation into primary spermatocytes, human recombinant SCF (rhSCF) was added to organ culture of testicular fragments. rhSCF was found to stimulate the spermatogonial proliferation and the spermatogonia progressed to the seventh generation that is the penultimate stage before primary spermatocyte stage. However, the spermatogonia did not differentiate into primary spermatocytes, but instead died of apoptosis. These results indicate that rhSCF promotes the proliferation of newt spermatogonia, but not the initiation of meiosis.
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Affiliation(s)
- Keisuke Abé
- Department of Materials and Life Science, Graduate School of Science and Technology, Kumamoto University, Kurokami 2-39-1, Kumamoto 860-8555, Japan
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Canosa LF, Ceballos NR. In vitro hCG and human recombinant FSH actions on testicular steroidogenesis in the toad Bufo arenarum. Gen Comp Endocrinol 2002; 126:318-24. [PMID: 12093119 DOI: 10.1016/s0016-6480(02)00007-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In order to study the regulation of testicular steroidogenesis in the toad Bufo arenarum, the effect of gonadotropins (hCG and hrFSH) on steroidogenic enzymes was determined using an in vitro system. 3beta-Hydroxysteroid dehydrogenase/isomerase activity was not affected by any of the gonadotropins, at any of the concentrations used. In contrast, 5alpha-reductase activity was strongly reduced by both hCG and hrFSH. Human chorionic gonadotropin inhibited the activity of cytochrome P450 17alpha-hydroxylase-C(17-20) lyase (P450(c17)), only at the highest concentration used, while hrFSH strongly reduced P450(c17) activity at all the doses assayed. In conclusion, these data suggest that LH (hCG) and FSH regulate steroidogenic enzymes such as 5alphaRed and P450(c17). The results also suggest that FSH could be involved in the regulation of the change in steroidogenesis undergone by the testis during the breeding season. In turn, the inhibition of P450(c17) activity could result in a reduction of androgen production and an increment of C21 steroids.
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Affiliation(s)
- L F Canosa
- PRHOM-CONICET and Laboratorio de Endocrinología Comparada, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas y Naturales, Pabellón 2, Universidad de Buenos Aires, C1428 EHA Buenos Aires, Argentina
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Yazawa T, Yamamoto T, Jin Y, Abé SI. Follicle-stimulating hormone is indispensable for the last spermatogonial mitosis preceding meiosis initiation in newts (Cynops pyrrhogaster). Biol Reprod 2002; 66:14-20. [PMID: 11751258 DOI: 10.1095/biolreprod66.1.14] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
We previously reported that mammalian FSH induced differentiation of secondary spermatogonia into primary spermatocytes in organ culture of newt testicular fragments, whereas in medium lacking FSH primary spermatocytes never appeared. Here, we investigated why spermatogonia fail to form primary spermatocytes in the absence of FSH. Spermatogonia maintained proliferative activity and viability at about half the level of those cultured in the presence of FSH, progressed into the seventh generation, but became moribund during the G2/M phase. Thus, the eighth generation of spermatogonia never appeared, suggesting that cell death is the chief reason why primary spermatocytes fail to form in the absence of FSH. The presence of Dmc1, a molecular marker for the spermatocyte stage, confirmed our microscopic observations that spermatogonia differentiated into primary spermatocytes in the presence of FSH. Thus, FSH is indispensable for the completion of the last spermatogonial mitosis, a prerequisite for the conversion of germ cells from mitosis to meiosis. Because prolactin induced apoptosis in spermatogonia during the seventh generation, we propose that a checkpoint exists for the initiation of meiosis in the seventh generation whereby spermatogonia enter meiosis when the concentration ratio of FSH to prolactin is high but fail to do so when the ratio is low.
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Affiliation(s)
- Takashi Yazawa
- Department of Materials and Life Science, Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan
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