Testosterone Administration to Mares during Estrus: Duration of Estrus and Diestrus and Concentrations of LH and FSH in Plasma

Thompson, Donald L.; Reville, S. I.; Walker, Michael P.; Derrick, D. J.; Papkoff, Harold

doi:10.2527/jas1983.564911x

Cited by 58 publications

(8 citation statements)

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“…Testosterone concentrations in follicular fluid were not different between groups at Hour 30 but reportedly increase during the preovulatory period in both the follicular fluid [15] and in the plasma [18]. These considerations are compatible with the present interpretation of an intrafollicular role of P 4 in oocyte maturation and a reported systemic effect of testosterone on accumulation of FSH in the pituitary during estrus in 206 mares [42]. Thus, the effects of follicle-produced P 4 may be local, as opposed to only systemic effects of testosterone.…”

supporting

confidence: 90%

Relationships of Follicle Versus Oocyte Maturity to Ultrasound Morphology, Blood Flow, and Hormone Concentrations of the Preovulatory Follicle in Mares1

Ginther¹,

Gastal

Gastal³

et al. 2007

Biology of Reproduction

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The effects of ultrasound morphology, vascularity, and follicular-fluid hormones of the preovulatory follicle on oocyte recovery rate and on follicle and oocyte maturity rates were studied for 60 spontaneous and solitary preovulatory follicles in mares. An ovulation-inducing dose of hCG was given when the follicle was >or=32 mm (Hour 0), and a procedure for oocyte recovery was done 30 h later (Hour 30). Between Hours 0 and 30, diameter of the follicle increased less and circulating estradiol (E2) concentrations decreased more in groups with successful versus nonsuccessful oocyte recovery and in groups with mature versus immature recovered oocytes, as indicated by significant interactions of group and hour. Significant differences in blood-flow end points between groups were not detected. At Hour 30, the frequency of granulosa serration, an indicator of impending ovulation, was higher (P < 0.001), and the number and expansion of granulosa cells in the lavaging fluid, indicators of follicle maturity, were greater in the oocyte-recovery group and in the oocyte-mature group. Follicular-fluid concentrations of E2, progesterone, and free insulin-like growth factor (IGF) 1 were not different between the oocyte-recovery and -nonrecovery groups. Concentration of progesterone was significantly greater, and E2 and free IGF1 were less in the oocyte-mature than in the immature groups. Results indicated that the post-hCG oocyte-recovery and oocyte-maturity rates were positively affected by follicle maturity. Greater follicular-fluid progesterone and lower E2 and free IGF concentrations were associated temporally with maturation of the oocyte but not with maturation of the follicle.

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supporting

confidence: 90%

Relationships of Follicle Versus Oocyte Maturity to Ultrasound Morphology, Blood Flow, and Hormone Concentrations of the Preovulatory Follicle in Mares1

Ginther¹,

Gastal

Gastal³

et al. 2007

Biology of Reproduction

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“…The present results do not support the hypothesis that androgens from the ovary during estrus stimulate FSH secretion during the subsequent diestrus in mares (Thompson et al, 1983d). Thus, the stimulation of FSH secretion during diestrus reported by Thompson et al (1983d) was possibly a pharmacologic rather than physiologic effect of testosterone. Alternatively, it may be that the short-term immunization of mares in the present experiment was not sufficient to detect an androgen involvement with FSH secretion.…”

Section: Discussioncontrasting

confidence: 99%

“…Received June 10, 1986. Accepted November 25, 1986 mares with testosterone during estrus increased FSH secretion during the subsequent diestrus (Thompson et al, 1983d). An alternative approach for studying the possible involvement of a hormone in various systems is active or passive immunization against the hormone (Nieshlag et al, 1974).…”

Section: Introductionmentioning

confidence: 99%

Passive Immunization of Cyclic Mares Against Androgen: Gonadotropin and Progesterone Concentrations and Estrous Characteristics

et al. 1987

Journal of Animal Science

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Antiserum generated in a horse against testosterone conjugated to bovine serum albumin (BSA) was administered to six lighthorse mares (androgen-immunized mares) 1 to 3 d before a prostaglandin-induced estrus and twice again at 2-d intervals. Six control mares were administered antiserum generated against BSA on the same schedule. Relative to testosterone, cross-reactivities of other steroids with the testosterone antiserum were (%): dihydrotestosterone, 52; 5 alpha-androstane-3 alpha,17 beta-diol, 8.6; androst-4-ene-3,17-dione, 1.2; and all others tested less than .1. Tritiated testosterone binding in plasma increased (P less than .01) in androgen-immunized mares within 1 h and remained elevated (P less than .01) relative to controls for greater than 21 d. There was no effect (P greater than .10) of passive immunization against androgen on interval to estrus after prostaglandin injection, duration of estrus, ovarian volume, number of palpable follicles or follicular volume during estrus. In contrast, concentrations of luteinizing hormone (LH) were higher (P less than .05) in androgen-immunized mares than in control mares during estrus and early diestrus. Concentrations of follicle stimulating hormone (FSH) and progesterone at those times were not affected (P greater than .10). From these data, we conclude that androgens in the mare during estrus may be involved with the regulation of LH secretion. In contrast, no involvement with FSH secretion was apparent under these short-term conditions.

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“…All blood samples in the experiment were placed on ice until centrifugation at 1,200 × g for 20 min at 5°C. Plasma was harvested and was stored at −15°C until assayed via RIA for LH (Thompson et al, 1983a), FSH (Thompson et al, 1983c), and progesterone (Diagnostic Systems Laboratory, Webster, TX, USA). Intra-and interassay coefficients of variation and assay sensitivities were 6%, 9%, and 0.2 ng/mL for LH; 7%, 11%, and 1.4 ng/mL for FSH; and 5%, 8%, and 0.05 ng/mL for progesterone.…”

Section: Methodsmentioning

confidence: 99%

Pituitary responsiveness to GnRH in mares following deslorelin acetate implantation to hasten ovulation

Johnson

Thompson²,

Cartmill³

2002

Journal of Animal Science

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The present experiment characterized the pituitary responsiveness to exogenous GnRH in the first 10 d after ovulation following commercially available deslorelin acetate implantation at the normal dosage for hastening ovulation in mares. Twelve mature, cyclic mares were assessed daily for estrus and three times weekly for ovarian activity starting May 1. Mares achieving a follicle at least 25 mm in diameter or showing signs of estrus were checked daily thereafter for ovarian characteristics. When a follicle >30 mm was detected, mares were administered either a single deslorelin acetate implant or a sham injection and then assessed daily for ovulation. On d 1, 4, 7, and 10 following ovulation, each mare was challenged i.v. with 50 microg GnRH, and blood samples were collected to characterize the LH and FSH responses. The size of the largest follicle on the day of treatment did not differ (P = 0.89) between groups. The number of days from treatment to ovulation was shorter (P < 0.001) by 2.0 d for the treated mares indicating a hastening of ovulation. The size of the largest follicle present on the days of GnRH challenge was larger in the treated mares on d 1 (P = 0.007) but smaller on d 10 (P = 0.02). In addition, the interovulatory interval was longer (P = 0.036) in the treated mares relative to controls by 4.4 d. Concentrations of FSH in plasma of the treated mares were lower (P < 0.05) than control concentrations from d 3 to 12; LH concentrations in the treated mares were lower (P < 0.05) relative to controls on d 0 to 5, d 7, and again on d 20 to 23. Progesterone values were the same (P = 0.99) for both groups from 2 d before ovulation though d 23. There was an interaction of treatment, day, and time of sampling (P < 0.001) for LH and FSH concentrations after injection of GnRH. Both the LH and FSH responses were suppressed (P < 0.009) in the treated mares relative to controls on d 1, 4, and 7; by d 10, the responses of the two groups were equivalent. In conclusion, deslorelin administration in this manner increased the interovulatory interval, consistently suppressed plasma LH and FSH concentrations, and resulted in a complete lack of responsiveness of LH and FSH to GnRH stimulation at the dose used during the first 7 d after the induced ovulation. Together, these results are consistent with a temporary down-regulation of the pituitary gland in response to deslorelin administered in this manner.

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Testosterone Administration to Mares during Estrus: Duration of Estrus and Diestrus and Concentrations of LH and FSH in Plasma

Cited by 58 publications

References 0 publications

Relationships of Follicle Versus Oocyte Maturity to Ultrasound Morphology, Blood Flow, and Hormone Concentrations of the Preovulatory Follicle in Mares1

Relationships of Follicle Versus Oocyte Maturity to Ultrasound Morphology, Blood Flow, and Hormone Concentrations of the Preovulatory Follicle in Mares1

Passive Immunization of Cyclic Mares Against Androgen: Gonadotropin and Progesterone Concentrations and Estrous Characteristics

Pituitary responsiveness to GnRH in mares following deslorelin acetate implantation to hasten ovulation

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