Peripheral concentrations of inhibin A, ovarian steroids, and gonadotropins associated with follicular development throughout the estrous cycle of the sow

Abstract

We investigated changes in peripheral concentrations of inhibin A, total inhibin, steroids, and gonadotropins throughout the intact estrous cycle of the sow in relation to ovarian changes determined by daily transrectal ultrasonography. All visible follicles of 3 mm or more in diameter were classified as small (R3 and !6 mm) or large (R6 mm). Follicular recruitment was identified in two periods of the cycle: one from the late luteal to the follicular phase, characterized by an increase in the number of small follicles followed by the appearance of large follicles; and another during the early luteal phase, consisting only of increased numbers of small follicles. Plasma concentrations of inhibin A increased (P!0.05), coinciding with the two periods of follicle emergence. Estradiol (E 2 ) levels increased (P!0.05) during the follicular phase, but not during the early luteal phase. An inverse relationship (P!0.01) between the patterns of inhibin and FSH concentrations was noted around the two periods of follicle emergence, but there was no relationship (PR0.1) between the patterns of plasma E 2 and FSH during the early luteal phase. In conclusion, measurement of plasma inhibin A levels combined with ultrasonographic examination of the ovaries revealed two periods of synchronous follicular growth during the sow's estrous cycle. The results strongly suggest that inhibin A functions as a negative feedback regulator of FSH secretion throughout the estrous cycle, whereas E 2 appears to influence FSH secretion only during the follicular phase.Reproduction (2010) 139 153-161

Estrous and ovulatory responses following cervical artificial insemination in Thai-native goats given a new or once-used controlled internal drug release with human chorionic gonadotropin

“…Although duration of estrus for the once-used CIDR was significantly shorter (21.4 ±1.4 h) compared to the new CIDR (26.1±1.1 h), it was still in a normal range of time (Baril and Vallet 1990;Fonseca et al 2008). Behavioral duration of estrus is also influenced by breed and steroid hormone concentrations (Medan et al 2003;Noguchi et al 2010). The difference can be explained by the association of the size of the dominant follicle and estradiol concentrations (Medan et al 2005).…”

Dynamics of insulin-like factor 3 and its receptor expression in boar testes

“…Testosterone and E 2 were extracted from the serum samples with diethyl ether before being applied to the kits. LH and FSH were also determined by TR-FIA, as previously reported (Noguchi et al 2010). Porcine FSH and LH immunoassay kits were provided by Dr A F Parlow (National Hormone and Peptide Program, Harbor-UCLA Medical Center, Torrance, CA, USA).…”

Reproductive Hormone Profiles in Sows on Estrus Synchronization using Estradiol Dipropionate and Prostaglandin F_2α-Analogue and the Reproductive Performance in Female Pigs on Commercial Farms

“…Plasma was recovered after centrifugation of blood and stored at −20°C. After sows had been deemed to be in estrus, the ovaries were monitored at 4-hr interval with transrectal ultrasonography as described previously [15] to detect the timing of ovulation and number of ovulated follicles. Ovulation was defined as the time when there was a marked reduction in the number of large follicles (≥6 mm in diameter) relative to that in previous observations [12].…”