Estrogen Feedback in the Pig: Sexual Differentiation and the Effect of Prenatal Testosterone Treatment

Elsaesser, Folkmar; Parvizi, Nahid

doi:10.1095/biolreprod20.5.1187

Cited by 55 publications

(25 citation statements)

References 31 publications

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“…The well-known negative feedback of oestradiol observed after injection of oestradiol in non-lactating sows (Elsaesser and Parvizi, 1979;Stevenson et al, 1981) was not apparent in this study or in other studies (Cox et al, 1988 (Ellendorff et al, 1988) (Barb et al, 1986, Mattioli et al, 1986) and since morphine, an endogenous opioid agonist, is able to shorten the duration of oestrus (Esbenshade and Huff, 1989). In the Mei-shan, the duration of OB-induced oestrus was similar to that described by Ellendorff et al (1988) …”

contrasting

confidence: 52%

Oestrus and LH reponses to oestradiol during lactational anoestrus in Chinese Meishan and Large White sows

Elsaesser

Martinat-Botté²,

Parvizi³

et al. 1992

Reprod. Nutr. Dev.

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Summary ― To investigate endocrine mechanisms associated with the occasional occurrence of fertile oestrus during lactation in the high prolific Chinese Meishan (MS) breed, the incidence of oestrus and changes in plasma luteinizing hormone (LH) levels before and after oestradiol benzoate (OB, 15 5 og/kg body weight) administration on day 22 was compared in 4 MS and 6 Large White (LW) sows. All sows exhibited oestrus in response to OB. Only 1 sow (MS) ovulated in response to OB, became pregnant and farrowed. Mean plasma LH levels before OB were low (MS: 0.38 ± 0.06 ng LH/ml, LW: 0.29 ± 0.04 ng LH/ml, ns). LH levels above 2 ng/ml (surge) occurred in 2/4 MS and 2/6 LW sows at 60 ± 5 h after OB. The MS sow that ovulated had an LH surge level of 4.5 ng/ml plasma at 40 h after OB. These results indicate minor breed differences in the control of LH secretion during lactational anoestrus.

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contrasting

confidence: 52%

Oestrus and LH reponses to oestradiol during lactational anoestrus in Chinese Meishan and Large White sows

Elsaesser

Martinat-Botté²,

Parvizi³

et al. 1992

Reprod. Nutr. Dev.

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“…(14)(15)(16)(17). Our observation that this gonadotropin response was completely blocked in five of eight gilts given AI-MAX further emphasizes the requirement for a central signal.…”

Section: Discussionmentioning

confidence: 68%

“…Lesions placed in the mediobasal anterior hypothalamus of pigs result in polyfollicular and cystic ovaries, without formation of corpora lutea (14), while pentobarbitone blocks or delays the LH surge in a majority of pigs anesthetized during proestrus (15). In addition, E 2 induces a LH surge in female, but not male pigs (1,16), and a single dose of E 2 induces circadian surging of LH in prepuberal pigs (2,17); phenomena most readily explained by central involvement.…”

mentioning

confidence: 99%

Absence of an Estradiol-Induced Surge of Luteinizing Hormone in Pigs Receiving Unvarying Pulsatile Gonadotropin-Releasing Hormone Stimulation*

Kesner¹,

Kraeling²,

Rampacek³

et al. 1987

Endocrinology

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The goal of this study was to pharmacologically block central nervous system (CNS) input to gonadotropes in mature ovariectomized gilts to determine the direct actions of estradiol (E2) on pituitary LH release when given at a dose sufficient to elicit a gonadotropin surge. Feeding AIMAX [N-methyl-N'-(1-methyl-2-propenyl)1,2-hydrazinedicarbothioamide; 125 mg/day] for 7 days reduced serum LH concentrations from 1.25 +/- 0.13 (mean +/- SE) to less than 0.18 ng/ml, abolished LH pulses, but did not compromise LH release in response to exogenous GnRH. Serum FSH concentrations were reduced by 27%, whereas serum concentrations of PRL, GH, thyroid hormones and cortisol were not affected after 7 days of AIMAX treatment. Behavior was not altered, aside from a slightly reduced appetite. The LH surge that peaked 48-80 h after injecting E2 benzoate (E2B) into control gilts was blocked in five of eight gilts given AIMAX. Giving GnRH pulses (1 microgram every 45 min) to AIMAX-treated gilts restored mean serum LH concentrations as well as the frequency and amplitude of LH pulses to those of untreated ovariectomized gilts. E2B suppressed the LH response to these GnRH pulses by 88% at 12 h, whereas from 24-96 h after E2B treatment, the LH response to GnRH and mean serum concentrations of LH were again similar to those of controls not given estradiol. These data indicate that induction of the gonadotropin surge by E2 in the gilt requires CNS input. The action of E2 on the pituitary in the presence of unvarying GnRH pulsation may, however, be limited to an early transient inhibition of responsiveness to GnRH, with no subsequent direct stimulation during the period of the surge.

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“…This differs from ineffective negative feedback regulation of LH secretion during this period [41][42][43]. With increasing age, MS alleles for the X chromosome QTL identified boars with greater concentrations of FSH and LH and smaller testicles of darker color.…”

Section: Discussionmentioning

confidence: 87%

Interrelationships of Porcine X and Y Chromosomes with Pituitary Gonadotropins and Testicular Size1

Ford

Wise

Lunstra

et al. 2001

Biology of Reproduction

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Endocrine and testicular responses to unilateral castration on 1, 10, 56, or 112 days of age were characterized in 132 Chinese Meishan (MS) x White composite (WC) crossbred boars in which testicular size associates with a quantitative trait locus (QTL) on X chromosome. At 220 days of age, testicles of boars unilaterally castrated on Day 1 or 10 weighed more and had greater total daily sperm production (DSP) than one testicle of bilaterally intact boars (P < 0.05); compensation did not double these two responses. Boars with MS alleles at the X chromosome QTL had smaller testicles, darker colored parenchyma, and lower total DSP than boars with WC alleles (P < 0.05). The MS alleles engendered greater (P < 0.05) plasma FSH and LH during puberty than WC alleles. Plasma FSH increased (P < 0.05) within 48 h of unilateral castration on Days 1, 10, and 56. Subsequent increases occurred earlier during puberty (P < 0.05) after unilateral castration at younger ages than after unilateral castration at older ages. Pubertal increases in plasma FSH and LH were greater (P < 0.05) in boars with MS alleles than in those with WC alleles for the X chromosome QTL. Breed of Y chromosome had no effect on testicular traits, FSH, testosterone, or estrone. For LH, boars with an MS Y chromosome had greater (P < 0.01) plasma LH across all ages than boars with a WC Y chromosome. We conclude that a gene or groups of genes that reside on the porcine X chromosome regulate testicular development and pubertal gonadotropin concentrations.

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Estrogen Feedback in the Pig: Sexual Differentiation and the Effect of Prenatal Testosterone Treatment

Abstract: We studied the stimulatory estrogen feedback on LH release in newborn (6-day-old) and prepubertal (160-day-old) male and female Landrace pigs and the effect of exposure to testosterone in

Cited by 55 publications

References 31 publications

Oestrus and LH reponses to oestradiol during lactational anoestrus in Chinese Meishan and Large White sows

Oestrus and LH reponses to oestradiol during lactational anoestrus in Chinese Meishan and Large White sows

Absence of an Estradiol-Induced Surge of Luteinizing Hormone in Pigs Receiving Unvarying Pulsatile Gonadotropin-Releasing Hormone Stimulation*

Interrelationships of Porcine X and Y Chromosomes with Pituitary Gonadotropins and Testicular Size1

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