The effect of deslorelin acetate on the oestrous cycle of female guinea pigs

Abstract

Deslorelin acetate, a GnRH agonist, is commonly used to prevent folliculogenesis in several species. However, little is known of the effect of deslorelin acetate implants on the oestrous cycle of female guinea pigs. Fifteen intact healthy female guinea pigs were investigated in this study. Signs of sexual behaviour, the presence of a vaginal membrane along with plasma concentrations of oestradiol (E 2 ) and progesterone (P 4 ), were monitored during two consecutive oestrous cycles. At the beginning of the third oestrous cycle each guinea pig was administered an implant of the GnRH analogue, deslorelin acetate, (4.7 mg). When compared to the untreated state, deslorelin implantation was associated with altered signs of oestrus. The average time to opening of the vaginal membrane was delayed. After opening, the vaginas were found to be variably opened and closed. A significant reduction in P 4 (to less than 1.0 ng/ml) and cessation of P 4 cyclical variation was observed. Plasma E 2 remained high during the whole experimental period. This study shows that cessation of the oestrous cycle by the deslorelin implant might be useful in preventing pregnancy in guinea pigs.Keywords: guinea pig; deslorelin; progesterone; oestradiol; oestrous cycle List of abbreviations E 2 = oestradiol, FSH = follicle-stimulating hormone, GnRH = gonadotropin-releasing hormone, gpGnRH = guinea pig gonadotropin-releasing hormone, LH = luteinising hormone, P 4 = progesterone

Effect of thymectomy on the female reproductive cycle in neonatal guinea pigs

“…Those results show that the lack of thymulin during the initial 8 days Guinea pigs are poly estrous animals, ovulate spontaneously, and have a mean estrous cycle length of 17.5 ± 2.1 days. This cycle is composed of diestrus, when the female is sexually inactive and the vagina is closed by an epithelial membrane, followed by the proestrus and estrus phases [32]. In the present study, neonatally thymectomized female guinea pigs displayed no significant difference in the mean length of the estrous cycle (17 ± 0.5 days) when compared to the sham operated animals (16 ± 1.5 days).…”

“…Blood samples were collected to test for gonadotropins and 17β-estradiol on day 0 and at 3 day intervals during the estrous cycle, for a total of 15 days [32]. FSH and LH levels were estimated using the enzyme-linked immunosorbent assay (ELISA) method.…”

“…Estradiol was measured by radioimmunoassay using the solid-phase iodine 125 technique, with a Coat-A-Count kits (Diagnostic Products Corp., Los Angeles, CA, USA), following the method described by Beckman. Serum gonadotropin and 17β-estradiol hormonal assays were analyzed at several points (days 0, 3, 6, 9, 12, and 15) during the estrus cycle in both groups [32].…”

Effect of thymectomy on the female reproductive cycle in prepubertal and pubertal female guinea pigs

“…Gonadotropins and 17β-estradiol were assayed on day 0 and at three-day intervals during the oestrous cycle, for a total of 15days (Kohutova et al, 2016). FSH and LH levels were estimated using the enzyme-linked immunosorbent assay (ELISA) method.…”