Effects of Androgens on Serum Concentrations of Gonadotropins and Ovarian Steroids in Gilts1

Abstract

To examine how androgens affect endocrine events associated with increased ovulation rate, gilts were injected with androgen receptor agonists, an antagonist, or a combination of both. Blood samples were collected hourly from Day 13 to estrus (Day 0 = onset of estrus) coincident with gilts (n = 6 per treatment) receiving daily treatments of vehicle (corn oil), 10 mg of testosterone, 10 mg of 5 alpha-dihydrotestosterone (dihydrotestosterone), 1.5 g of flutamide (an androgen receptor antagonist), testosterone plus flutamide, or dihydrotestosterone plus flutamide. Treatment of gilts with testosterone or dihydrotestosterone alone increased (P < 0.05) concentrations of FSH in serum, and these effects were blocked by cotreatment with flutamide. Estradiol-17beta and androstenedione concentrations in serum were increased (P < 0.05) at 2 h after injection of testosterone or testosterone plus flutamide but not after dihydrotestosterone treatment, probably because of the role of testosterone as a substrate for estradiol-17beta and androstenedione synthesis. There were no effects of the six treatments on serum concentrations of progesterone during luteolysis, but treating gilts with testosterone shortened (P < 0.05) the proestrous period. Total embryonic loss by Day 11 in gilts treated with dihydrotestosterone was reversed when gilts were cotreated with dihydrotestosterone plus flutamide. Results of this experiment indicated that androgen actions both increased FSH secretion and reduced embryonic survival by a mechanism(s) dependent on the androgen receptor.

Androgen Deficiency During Mid- and Late Pregnancy Alters Progesterone Production and Metabolism in the Porcine Corpus Luteum

“…The P4 production in small and large luteal porcine cells is stimulated by luteinizing hormone (LH). 52 Jimenez et al 53 demonstrated that the LH level is significantly decreased following the administration of testosterone or dihydrotestosterone plus flutamide in gilts. An indirect action of androgens via changes in LH rather than a direct effect may be responsible for the observed changes in the GD90F large luteal cells.…”

A meta-analysis: Effect of androgens on reproduction in sows

“…Figure 1 shows the process of paper selection. Finally, 10 papers (10, [19][20][21][22][25][26][27][28][29] were selected. The results comprised 31 data sets, and the specific contents used in the study are listed in Table 2.…”

“…Previous studies have reported that after the injection of exogenous T, both the ovulation and the embryo survival rates of sows improved (19,20). In contrast, Jimenez reported that although the ovulation rate of sows improved after T injection, the survival rate of embryos was reduced (21). In particular, the embryo survival rate of sows after DHT injection decreased significantly (21,22).…”

“…In contrast, Jimenez reported that although the ovulation rate of sows improved after T injection, the survival rate of embryos was reduced (21). In particular, the embryo survival rate of sows after DHT injection decreased significantly (21,22). Recently, it has been reported that T has no relationship with the litter size of sows (23).…”

Ovulatory Response of Weaned Sows to an Altered Ratio of Exogenous Gonadotrophins

“…The mechanism whereby the ovary was apparently made more responsive to an ovulatory signal is not known. The hCG can be expected to increase production of follicular testosterone which, in turn, may increase circulating FSH concentrations [10]. Higher FSH levels in association with the increased LH activity from the hCG may be associated with the more rapid follicular growth and, presumably, follicular maturation.…”