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Han X, Zhou Y, Zeng Y, Sui F, Liu Y, Tan Y, Cao X, Du X, Meng F, Zeng X. Effects of active immunization against GnRH versus surgical castration on hypothalamic-pituitary function in boars. Theriogenology 2017; 97:89-97. [PMID: 28583614 DOI: 10.1016/j.theriogenology.2017.04.038] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 04/24/2017] [Accepted: 04/24/2017] [Indexed: 11/17/2022]
Abstract
The objective was to compare effects of anti-GnRH immunization (immunocastration) versus surgical castration on hypothalamic-pituitary function in boars. Thirty-six boars were randomly divided into three groups (n = 12/group): control, surgically castrated, or immunized against GnRH at 10 wk of age (boostered 8 wk later). Compared to intact boars, immunocastration reduced (P < 0.05) serum concentrations of LH, FSH, testosterone and inhibin B and caused severe testicular atrophy, whereas surgical castration increased (P < 0.05) serum concentrations of LH and FSH. Both immunocastration and surgical castration consistently reduced hypothalamic GnRH synthesis, with decreased (P < 0.05) mRNA expressions of GnRH, GnRH up-stream gatekeeper genes kiss1 and its receptor (GPR54), and androgen receptor in the hypothalamic arcuate nucleus (ARC) and anteroventral periventricular nucleus (AVPV), as well as GnRH content in the median eminence. Inconsistently, mRNA expressions of gonadotropin-inhibitory hormone (GnIH) in ARC and AVPV as well as its receptor (GPR147) in pituitary were selectively reduced (P < 0.05), but mRNA expressions of estrogen receptor alpha and aromatase (CPY17A1) in pituitary were selectively increased (P < 0.05) in surgical castrates. In response to selectively attenuated suppressive signaling from GnIH and testosterone, mRNA expressions of GnRH receptor (GnRHR), LH-β and FSH-β in pituitary were increased (P < 0.05) in surgical castrates, whereas these pituitary gene expressions were decreased (P < 0.05) in immunocastrates, due to loss of hypothalamic GnRH signaling. We concluded that immunocastration and surgical castration consistently reduced hypothalamic GnRH synthesis due to a testosterone deficiency disrupting testosterone-Kisspeptin-GPR54-GnRH signaling pathways. Furthermore, selectively attenuated GnIH and testosterone signaling in the pituitary increased gonadotropin production in surgical castrates.
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Affiliation(s)
- Xingfa Han
- Isotope Research Lab, Biological Engineering and Application Biology Department, Sichuan Agricultural University, Ya'an, 625014, PR China
| | - Yuqin Zhou
- Isotope Research Lab, Biological Engineering and Application Biology Department, Sichuan Agricultural University, Ya'an, 625014, PR China
| | - Yu Zeng
- College of Animal Science, Sichuan Agricultural University, Chengdu Campus, Chengdu, Sichuan, 611130, PR China
| | - Fenfen Sui
- Isotope Research Lab, Biological Engineering and Application Biology Department, Sichuan Agricultural University, Ya'an, 625014, PR China
| | - Yacheng Liu
- Isotope Research Lab, Biological Engineering and Application Biology Department, Sichuan Agricultural University, Ya'an, 625014, PR China
| | - Yao Tan
- Isotope Research Lab, Biological Engineering and Application Biology Department, Sichuan Agricultural University, Ya'an, 625014, PR China
| | - Xiaohan Cao
- Isotope Research Lab, Biological Engineering and Application Biology Department, Sichuan Agricultural University, Ya'an, 625014, PR China
| | - Xiaogang Du
- Isotope Research Lab, Biological Engineering and Application Biology Department, Sichuan Agricultural University, Ya'an, 625014, PR China
| | - Fengyan Meng
- Isotope Research Lab, Biological Engineering and Application Biology Department, Sichuan Agricultural University, Ya'an, 625014, PR China
| | - Xianyin Zeng
- Isotope Research Lab, Biological Engineering and Application Biology Department, Sichuan Agricultural University, Ya'an, 625014, PR China.
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Stormshak F, Estill CT, Resko JA, Roselli CE. Changes in LH secretion in response to an estradiol challenge in male- and female-oriented rams and in ewes. Reproduction 2008; 135:733-8. [PMID: 18304985 DOI: 10.1530/rep-07-0505] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Two experiments were conducted to determine whether an estradiol challenge could cause a female-type LH surge in castrated male- and female-oriented rams (MORs and FORs). Administration of 17beta-estradiol to castrated MORs and FORs and ovariectomized ewes caused an initial reduction in LH secretion followed for 12-20 h by a surge release of LH in the ewes. No surge release of LH occurred in the MORs and FORs. The pattern of changes in LH secretion within rams and ewes did not differ between the breeding and nonbreeding seasons. Treatment failed to elicit female-typical receptive sexual behaviors in the rams but did stimulate increased sexual receptivity in the ewes as determined by the measures of responsiveness to the teaser ram. Overall, no differences were found in hypothalamic-hypophyseal function in response to exogenous estradiol between MORs and FORs. These data are interpreted to suggest that in contrast to sexual attraction, the neural mechanisms controlling the LH surge and female receptivity are defeminized in MORs.
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Affiliation(s)
- F Stormshak
- Department of Animal Sciences College of Veterinary Medicine, Oregon State University, Corvallis, Oregon 97331-4501, USA
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McManus CJ, Goodman RL, Llanza NV, Valent M, Dobbins AB, Connors JM, Hileman SM. Inhibition of luteinizing hormone secretion by localized administration of estrogen, but not dihydrotestosterone, is enhanced in the ventromedial hypothalamus during feed restriction in the young wether. Biol Reprod 2005; 73:781-9. [PMID: 15972883 DOI: 10.1095/biolreprod.105.042275] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The ability of steroids to inhibit LH secretion is enhanced during undernutrition. To identify potential hypothalamic sites at which this enhancement may occur, we examined LH secretion in feed-restricted or fed young wethers treated with locally administered metabolites of testosterone. In experiment 1, microimplants containing crystalline estradiol-17beta (E) or cholesterol were administered via chronic guide tubes directed to the preoptic area (POA) or ventromedial hypothalamus (VMH) in fed or feed-restricted wethers. E treatment in the VMH decreased LH pulse frequency, pulse amplitude, and mean LH concentration in feed-restricted, but not fed, wethers. E may act in the POA to suppress LH under feed restriction, but definite conclusions cannot be drawn because of steroid-independent effects of feed restriction on LH pulse frequency. In experiment 2, the effect of dihydrotestosterone (DHT) in the VMH was determined. DHT administration to the VMH did not alter LH secretion in either feed-restricted or fed wethers. Thus the VMH is one site wherein E negative feedback is enhanced during feed restriction in the wether. In contrast, we found no evidence for enhanced responsiveness to androgen negative feedback within the VMH of feed-restricted wethers. We suggest that increased sensitivity within the VMH to E, but not to DHT, is important for suppressing LH secretion in undernourished male sheep.
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Affiliation(s)
- Christina J McManus
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, 26506-9229, USA.
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