1
|
Ahn JS, Kwon EG, Lee HJ, Lee EM, Hwang SM, Cho SR, Kim KW, Kim UH, Won JI, Jin S, Kang SS, Park BK, Jang GS, Jang SS. Effect of Hemi-Castration on the Productivity, Histological Characteristics, and Economic Efficacy of Korean Beef Cattle. Animals (Basel) 2021; 11:ani11092490. [PMID: 34573457 PMCID: PMC8470760 DOI: 10.3390/ani11092490] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 08/19/2021] [Accepted: 08/21/2021] [Indexed: 11/16/2022] Open
Abstract
We evaluated the growth performance, serum testosterone, carcass traits, histological characteristics, and economic efficacy of castrated and hemi-castrated Korean beef cattle. Thirty-two Hanwoo calves (Initial body weight: 148.4 ± 19.8 kg) were randomly assigned into the castrated Hanwoo (CH) and hemi-castrated Hanwoo (HH) group. The experiment lasted 18 months; the animals were all slaughtered on the same day. Final body weight and average daily gain (ADG) tended to increase in the HH group compared to the CH group. Testosterone concentration was higher in HH group (5.27-14.27 ng/dL) than in the CH group (0.47-0.70 ng/dL) during the whole experimental period after castration (p < 0.05). Rib eye area was 17.08 cm2 wider in HH group than in CH group, but marbling score was improved by 3.33 in CH group compared to HH group (p < 0.01). Deposition area of adipocytes in Longissimus dorsi were higher in CH group than in HH group (p < 0.001). Net income per head was 1760 US dollar higher in the CH group than in the HH group (p < 0.04). Thus, our findings suggest that hemi-castration had positive effects on the increase in ADG and meat yield traits, with negative effects on marbling and profitability.
Collapse
Affiliation(s)
- Jun-Sang Ahn
- Hanwoo Research Institute, National Institute of Animal Science, RDA, Pyeongchang 25340, Korea; (J.-S.A.); (H.-J.L.); (E.-M.L.); (S.-M.H.); (S.-R.C.); (K.-W.K.); (U.-H.K.); (J.-I.W.); (S.J.); (S.-S.K.); (G.-S.J.)
| | - Eung-Gi Kwon
- Department of Animal Science, Kangwon National University, Chunchoen 24341, Korea; (E.-G.K.); (B.-K.P.)
| | - Hyun-Jeong Lee
- Hanwoo Research Institute, National Institute of Animal Science, RDA, Pyeongchang 25340, Korea; (J.-S.A.); (H.-J.L.); (E.-M.L.); (S.-M.H.); (S.-R.C.); (K.-W.K.); (U.-H.K.); (J.-I.W.); (S.J.); (S.-S.K.); (G.-S.J.)
| | - Eun-Mi Lee
- Hanwoo Research Institute, National Institute of Animal Science, RDA, Pyeongchang 25340, Korea; (J.-S.A.); (H.-J.L.); (E.-M.L.); (S.-M.H.); (S.-R.C.); (K.-W.K.); (U.-H.K.); (J.-I.W.); (S.J.); (S.-S.K.); (G.-S.J.)
| | - So-Mi Hwang
- Hanwoo Research Institute, National Institute of Animal Science, RDA, Pyeongchang 25340, Korea; (J.-S.A.); (H.-J.L.); (E.-M.L.); (S.-M.H.); (S.-R.C.); (K.-W.K.); (U.-H.K.); (J.-I.W.); (S.J.); (S.-S.K.); (G.-S.J.)
| | - Sang-Rae Cho
- Hanwoo Research Institute, National Institute of Animal Science, RDA, Pyeongchang 25340, Korea; (J.-S.A.); (H.-J.L.); (E.-M.L.); (S.-M.H.); (S.-R.C.); (K.-W.K.); (U.-H.K.); (J.-I.W.); (S.J.); (S.-S.K.); (G.-S.J.)
| | - Kyung-Woon Kim
- Hanwoo Research Institute, National Institute of Animal Science, RDA, Pyeongchang 25340, Korea; (J.-S.A.); (H.-J.L.); (E.-M.L.); (S.-M.H.); (S.-R.C.); (K.-W.K.); (U.-H.K.); (J.-I.W.); (S.J.); (S.-S.K.); (G.-S.J.)
| | - Ui-Hyung Kim
- Hanwoo Research Institute, National Institute of Animal Science, RDA, Pyeongchang 25340, Korea; (J.-S.A.); (H.-J.L.); (E.-M.L.); (S.-M.H.); (S.-R.C.); (K.-W.K.); (U.-H.K.); (J.-I.W.); (S.J.); (S.-S.K.); (G.-S.J.)
| | - Jeong-Il Won
- Hanwoo Research Institute, National Institute of Animal Science, RDA, Pyeongchang 25340, Korea; (J.-S.A.); (H.-J.L.); (E.-M.L.); (S.-M.H.); (S.-R.C.); (K.-W.K.); (U.-H.K.); (J.-I.W.); (S.J.); (S.-S.K.); (G.-S.J.)
| | - Shil Jin
- Hanwoo Research Institute, National Institute of Animal Science, RDA, Pyeongchang 25340, Korea; (J.-S.A.); (H.-J.L.); (E.-M.L.); (S.-M.H.); (S.-R.C.); (K.-W.K.); (U.-H.K.); (J.-I.W.); (S.J.); (S.-S.K.); (G.-S.J.)
| | - Sung-Sik Kang
- Hanwoo Research Institute, National Institute of Animal Science, RDA, Pyeongchang 25340, Korea; (J.-S.A.); (H.-J.L.); (E.-M.L.); (S.-M.H.); (S.-R.C.); (K.-W.K.); (U.-H.K.); (J.-I.W.); (S.J.); (S.-S.K.); (G.-S.J.)
| | - Byung-Ki Park
- Department of Animal Science, Kangwon National University, Chunchoen 24341, Korea; (E.-G.K.); (B.-K.P.)
| | - Gi-Suk Jang
- Hanwoo Research Institute, National Institute of Animal Science, RDA, Pyeongchang 25340, Korea; (J.-S.A.); (H.-J.L.); (E.-M.L.); (S.-M.H.); (S.-R.C.); (K.-W.K.); (U.-H.K.); (J.-I.W.); (S.J.); (S.-S.K.); (G.-S.J.)
| | - Sun-Sik Jang
- Hanwoo Research Institute, National Institute of Animal Science, RDA, Pyeongchang 25340, Korea; (J.-S.A.); (H.-J.L.); (E.-M.L.); (S.-M.H.); (S.-R.C.); (K.-W.K.); (U.-H.K.); (J.-I.W.); (S.J.); (S.-S.K.); (G.-S.J.)
- Correspondence: ; Tel.: +82-33-330-0693
| |
Collapse
|
2
|
Puttabyatappa M, Padmanabhan V. Ovarian and Extra-Ovarian Mediators in the Development of Polycystic Ovary Syndrome. J Mol Endocrinol 2018; 61:R161-R184. [PMID: 29941488 PMCID: PMC6192837 DOI: 10.1530/jme-18-0079] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 06/14/2018] [Accepted: 06/25/2018] [Indexed: 12/16/2022]
Abstract
Polycystic ovary syndrome (PCOS) is a heterogeneous endocrine disorder affecting women of reproductive age. The origin of PCOS is still not clear and appears to be a function of gene x environment interactions. This review addresses the current knowledge of the genetic and developmental contributions to the etiology of PCOS, the ovarian and extra-ovarian mediators of PCOS and the gaps and key challenges that need to be addressed in the diagnosis, treatment and prevention of PCOS.
Collapse
|
3
|
Morford JJ, Wu S, Mauvais-Jarvis F. The impact of androgen actions in neurons on metabolic health and disease. Mol Cell Endocrinol 2018; 465:92-102. [PMID: 28882554 PMCID: PMC5835167 DOI: 10.1016/j.mce.2017.09.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 08/25/2017] [Accepted: 09/01/2017] [Indexed: 01/03/2023]
Abstract
The male hormone testosterone exerts different effects on glucose and energy homeostasis in males and females. Testosterone deficiency predisposes males to visceral obesity, insulin resistance and type 2 diabetes. However, testosterone excess predisposes females to similar metabolic dysfunction. Here, we review the effects of testosterone actions in the central nervous system on metabolic function in males and females. In particular, we highlight changes within the hypothalamus that control glucose and energy homeostasis. We distinguish the organizational effects of testosterone in the programming of neural circuitry during development from the activational effects of testosterone during adulthood. Finally, we explore potential sites where androgen might be acting to impact metabolism within the central nervous system.
Collapse
Affiliation(s)
- Jamie J Morford
- Department of Medicine, Section of Endocrinology and Metabolism, Tulane University Health Sciences Center, School of Medicine, New Orleans, LA, USA
| | - Sheng Wu
- Department of Pediatrics and Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Franck Mauvais-Jarvis
- Department of Medicine, Section of Endocrinology and Metabolism, Tulane University Health Sciences Center, School of Medicine, New Orleans, LA, USA.
| |
Collapse
|
4
|
Cardoso RC, Puttabyatappa M, Padmanabhan V. Steroidogenic versus Metabolic Programming of Reproductive Neuroendocrine, Ovarian and Metabolic Dysfunctions. Neuroendocrinology 2015; 102:226-37. [PMID: 25832114 PMCID: PMC4591099 DOI: 10.1159/000381830] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 03/21/2015] [Indexed: 12/12/2022]
Abstract
The susceptibility of the reproductive system to early exposure to steroid hormones has become a major concern in our modern societies. Human fetuses are at risk of abnormal programming via exposure to endocrine disrupting chemicals, inadvertent use of contraceptive pills during pregnancy, as well as from excess exposure to steroids due to disease states. Animal models provide an unparalleled resource to understand the developmental origin of diseases. In female sheep, prenatal exposure to testosterone excess results in an array of adult reproductive disorders that recapitulate those seen in women with polycystic ovary syndrome (PCOS), including disrupted neuroendocrine feedback mechanisms, increased pituitary sensitivity to gonadotropin-releasing hormone, luteinizing hormone excess, functional hyperandrogenism, and multifollicular ovarian morphology culminating in early reproductive failure. Prenatal testosterone treatment also leads to fetal growth retardation, insulin resistance, and hypertension. Mounting evidence suggests that developmental exposure to an improper steroidal/metabolic environment may mediate the programming of adult disorders in prenatal testosterone-treated females, and these defects are maintained or amplified by the postnatal sex steroid and metabolic milieu. This review addresses the steroidal and metabolic contributions to the development and maintenance of the PCOS phenotype in the prenatal testosterone-treated sheep model, including the effects of prenatal and postnatal treatment with an androgen antagonist or insulin sensitizer as potential strategies to prevent/ameliorate these dysfunctions. Insights obtained from these intervention strategies on the mechanisms underlying these defects are likely to have translational relevance to human PCOS.
Collapse
Affiliation(s)
- Rodolfo C Cardoso
- Department of Pediatrics, University of Michigan, Ann Arbor, Mich., USA
| | | | | |
Collapse
|
5
|
Padmanabhan V, Veiga-Lopez A. Reproduction Symposium: developmental programming of reproductive and metabolic health. J Anim Sci 2014; 92:3199-210. [PMID: 25074449 PMCID: PMC4153374 DOI: 10.2527/jas.2014-7637] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Inappropriate programming of the reproductive system by developmental exposure to excess steroid hormones is of concern. Sheep are well suited for investigating developmental origin of reproductive and metabolic disorders. The developmental time line of female sheep (approximately 5 mo gestation and approximately 7 mo to puberty) is ideal for conducting sequential studies of the progression of metabolic and/or reproductive disruption from the developmental insult to manifestation of adult consequences. Major benefits of using sheep include knowledge of established critical periods to target adult defects, a rich understanding of reproductive neuroendocrine regulation, availability of noninvasive approaches to monitor follicular dynamics, established surgical approaches to obtain hypophyseal portal blood for measurement of hypothalamic hormones, and the ability to perform studies in natural setting thereby keeping behavioral interactions intact. Of importance is the ability to chronically instrument fetus and mother for determining early endocrine perturbations. Prenatal exposure of the female to excess testosterone (T) leads to an array of adult reproductive disorders that include LH excess, functional hyperandrogenism, neuroendocrine defects, multifollicular ovarian morphology, and corpus luteum dysfunction culminating in early reproductive failure. At the neuroendocrine level, all 3 feedback systems are compromised. At the pituitary level, gonadotrope (LH secretion) sensitivity to GnRH is increased. Multifollicular ovarian morphology stems from persistence of follicles as well as enhanced follicular recruitment. These defects culminate in progressive loss of cyclicity and reduced fecundity. Prenatal T excess also leads to fetal growth retardation, an early marker of adult reproductive and metabolic diseases, insulin resistance, hypertension, and behavioral deficits. Collectively, the reproductive and metabolic deficits of prenatal T-treated sheep provide proof of concept for the developmental origin of fertility and metabolic disorders. Studies with the environmental endocrine disruptor bisphenol A (BPA) show that reproductive disruptions found in prenatal BPA-treated sheep are similar to those seen in prenatal T-treated sheep. The ubiquitous exposure to endocrine disrupting compounds with steroidogenic potential via the environment and food sources calls for studies addressing the impact of developmental exposure to environmental steroid mimics on reproductive function.
Collapse
Affiliation(s)
- V Padmanabhan
- Departments of Pediatrics Obstetrics and Gynecology Molecular and Integrative Physiology Environmental Health Sciences, The University of Michigan, Ann Arbor 48108
| | | |
Collapse
|
6
|
Padmanabhan V, Sarma HN, Savabieasfahani M, Steckler TL, Veiga-Lopez A. Developmental reprogramming of reproductive and metabolic dysfunction in sheep: native steroids vs. environmental steroid receptor modulators. INTERNATIONAL JOURNAL OF ANDROLOGY 2010; 33:394-404. [PMID: 20070410 PMCID: PMC3970726 DOI: 10.1111/j.1365-2605.2009.01024.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The inappropriate programming of developing organ systems by exposure to excess native or environmental steroids, particularly the contamination of our environment and our food sources with synthetic endocrine disrupting chemicals that can interact with steroid receptors, is a major concern. Studies with native steroids have found that in utero exposure of sheep to excess testosterone, an oestrogen precursor, results in low birth weight offspring and leads to an array of adult reproductive/metabolic deficits manifested as cycle defects, functional hyperandrogenism, neuroendocrine/ovarian defects, insulin resistance and hypertension. Furthermore, the severity of reproductive dysfunction is amplified by excess postnatal weight gain. The constellation of adult reproductive and metabolic dysfunction in prenatal testosterone-treated sheep is similar to features seen in women with polycystic ovary syndrome. Prenatal dihydrotestosterone treatment failed to result in similar phenotype suggesting that many effects of prenatal testosterone excess are likely facilitated via aromatization to oestradiol. Similarly, exposure to environmental steroid imposters such as bisphenol A (BPA) and methoxychlor (MXC) from days 30 to 90 of gestation had long-term but differential effects. Exposure of sheep to BPA, which resulted in maternal levels of 30-50 ng/mL BPA, culminated in low birth weight offspring. These female offspring were hypergonadotropic during early postnatal life and characterized by severely dampened preovulatory LH surges. Prenatal MXC-treated females had normal birth weight and manifested delayed but normal amplitude LH surges. Importantly, the effects of BPA were evident at levels, which approximated twice the highest levels found in human maternal circulation of industrialized nations. These findings provide evidence in support of developmental origin of adult reproductive and metabolic diseases and highlight the risk posed by exposure to environmental endocrine disrupting chemicals.
Collapse
Affiliation(s)
- V Padmanabhan
- Department of Pediatrics and the Reproductive Sciences Program, The University of Michigan, Ann Arbor, MI48109, USA.
| | | | | | | | | |
Collapse
|
7
|
Kesler DJ, Favero RJ, Esarey JC, Berger LL. Controlled Delivery of Testosterone Propionate Suppresses Fertility in Treated Females and Induces Prenatal Androgenization in Female Offspring Without Phenotypic Masculinization. Drug Dev Ind Pharm 2008. [DOI: 10.3109/03639049509069242] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
8
|
Alexanderson C, Eriksson E, Stener-Victorin E, Lystig T, Gabrielsson B, Lönn M, Holmäng A. Postnatal testosterone exposure results in insulin resistance, enlarged mesenteric adipocytes, and an atherogenic lipid profile in adult female rats: comparisons with estradiol and dihydrotestosterone. Endocrinology 2007; 148:5369-76. [PMID: 17656458 DOI: 10.1210/en.2007-0305] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Postnatal events contribute to features of the metabolic syndrome in adulthood. In this study, postnatally administered testosterone reduced insulin sensitivity and increased the mesenteric fat depot, the size of mesenteric adipocytes, serum levels of total cholesterol, low-density lipoprotein cholesterol, and triglycerides, and the atherogenic index in adult female rats. To assess the involvement of estrogen and androgen receptors in these programming effects, we compared testosterone-exposed rats to rats exposed to estradiol or dihydrotestosterone (DHT). Estradiol-treated rats had lower insulin sensitivity than testosterone-treated rats and, like those rats, had enlarged mesenteric adipocytes and increased triglyceride levels. DHT also reduced insulin sensitivity but did not mimic the other metabolic effects of testosterone. All treated rats were probably anovulatory, but only those treated with testosterone had reduced testosterone levels. This study confirms our previous finding that postnatal administration of testosterone reduces insulin sensitivity in adult female rats and shows that this effect is accompanied by unfavorable changes in mesenteric fat tissue and in serum lipid levels. The findings in the estradiol and DHT groups suggest that estrogen receptors exert stronger metabolic programming effects than androgen receptors. Thus, insults such as sex hormone exposure in early life may have long-lasting effects, thereby creating a predisposition to disturbances in insulin sensitivity, adipose tissue, and lipid profile in adulthood.
Collapse
Affiliation(s)
- Camilla Alexanderson
- Institute of Neuroscience and Physiology, Department of Physiology/Endocrinology, Sahlgrenska Academy, Göteborg University, Box 434, 405 30, Göteborg, Sweden.
| | | | | | | | | | | | | |
Collapse
|
9
|
Manikkam M, Steckler TL, Welch KB, Inskeep EK, Padmanabhan V. Fetal programming: prenatal testosterone treatment leads to follicular persistence/luteal defects; partial restoration of ovarian function by cyclic progesterone treatment. Endocrinology 2006; 147:1997-2007. [PMID: 16373416 DOI: 10.1210/en.2005-1338] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Prenatal testosterone (T) excess during midgestation leads to estrous cycle defects and polycystic ovaries in sheep. We hypothesized that follicular persistence causes polycystic ovaries and that cyclic progesterone (P) treatment would overcome follicular persistence and restore cyclicity. Twice-weekly blood samples for P measurements were taken from control (C; n = 16) and prenatally T-treated (T60; n = 14; 100 mg T, im, twice weekly from d 30-90 of gestation) Suffolk sheep starting before the onset of puberty and continuing through the second breeding season. A subset of C and T60 sheep were treated cyclically with a modified controlled internal drug-releasing device for 13-14 d every 17 d during the first anestrus (CP, 7; TP, 6). Transrectal ovarian ultrasonography was performed for 8 d in the first and 21 d in the second breeding season. Prenatal T excess reduced the number, but increased the duration of progestogenic cycles, reduced the proportion of ewes with normal cycles, increased the proportion of ewes with subluteal cycles, decreased the proportion of ewes with ovulatory cycles, induced the occurrence of persistent follicles, and reduced the number of corpora lutea in those that cycled. Cyclic P treatment in anestrus, which produced one third the P concentration seen during luteal phase of cycle, did not reduce the number of persistent follicles, but increased the number of progestogenic cycles while reducing their duration. These findings suggested that follicular persistence might contribute to the polycystic ovarian morphology. Cyclic P treatment was able to only partially restore follicular dynamics, but this may be related to the low replacement concentrations of P achieved.
Collapse
Affiliation(s)
- Mohan Manikkam
- Department of Pediatrics, University of Michigan, Ann Arbor, 48109-0404, USA
| | | | | | | | | |
Collapse
|
10
|
Padmanabhan V, Manikkam M, Recabarren S, Foster D. Prenatal testosterone excess programs reproductive and metabolic dysfunction in the female. Mol Cell Endocrinol 2006; 246:165-74. [PMID: 16413112 DOI: 10.1016/j.mce.2005.11.016] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Findings discussed in this review stress the importance of normal estrogen and androgen signaling at appropriate developmental time points in maintaining normal phenotypic expression, reproductive and metabolic function and document how inappropriate steroid signaling, at inopportune times can have undesirable outcomes. For example, inappropriate testosterone exposure during fetal life alters the developmental trajectory of the female culminating in a suite of disorders, which include intrauterine growth-retardation and postnatal catch up growth, phenotypic masculinization, reproductive neuroendocrine and ovarian disruptions leading to progressive loss of cyclicity and metabolic disruptions manifested as hyperinsulinemia.
Collapse
Affiliation(s)
- Vasantha Padmanabhan
- Department of Pediatrics, University of Michigan, Ann Arbor, MI 48109-0404, USA.
| | | | | | | |
Collapse
|
11
|
Sharma TP, Herkimer C, West C, Ye W, Birch R, Robinson JE, Foster DL, Padmanabhan V. Fetal programming: prenatal androgen disrupts positive feedback actions of estradiol but does not affect timing of puberty in female sheep. Biol Reprod 2002; 66:924-33. [PMID: 11906910 DOI: 10.1095/biolreprod66.4.924] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
We studied the impact of prenatal androgen exposure on the timing of onset of puberty, maintenance of cyclicity in the first breeding season, and the LH surge mechanism in female sheep. Pregnant sheep were injected with testosterone propionate (100 mg i.m.) twice each week from Day 30 to Day 90 (D30-90) or from Day 60 to Day 90 (D60-90) of gestation (term = 147 days). Concentrations of plasma progesterone and gonadotropins were measured in blood samples collected twice each week from control (n = 10), D60-90 (n = 13), and D30-90 (n = 3) animals. Rate of weight gain and initiation of estrous behavior were also monitored. After the first breeding season, when the animals entered anestrus, competency of the gonadotropin surge system to respond to estradiol positive feedback was tested in the absence or presence of progesterone priming for 12 days. Prenatally androgenized females had similar body weight gain and achieved puberty (start of first progestogenic cycle) at the same time as controls. Duration of the breeding season and the number of cycles that occurred during the first breeding season were similar between control and prenatally androgenized sheep. In contrast, prenatal exposure to androgens compromised the positive feedback effects of estradiol. Onset of LH/FSH surges following the estradiol stimulus was delayed in both groups of androgenized ewes compared with the controls in both the absence and presence of progesterone priming. In addition, the magnitude of LH and FSH surges in the two animals that surged in the D30-90 group were only one third and one half, respectively, of the magnitudes observed in the control and D60-90 groups. The present findings indicate that disruption of the surge system can account for the fertility problems that occur during adulthood in prenatally androgenized sheep.
Collapse
|
12
|
Gill J, Hosking B, Egan A. Prenatal programming of mammalian growth—a review of the role of steroids. ACTA ACUST UNITED AC 1998. [DOI: 10.1016/s0301-6226(97)00155-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
13
|
Social, environmental and genetic factors in the ontogeny of phenotypic differentiation in a lizard with alternative male reproductive strategies. Behav Ecol Sociobiol 1993. [DOI: 10.1007/bf00216593] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|