Changes in Serum Immunoreactive Inhibin-α during Photoperiod-Induced Testicular Regression and Recrudescence in the Golden Hamster1

Abstract

Serum immunoreactive inhibin-alpha (irI alpha), FSH, LH, and testosterone (T) were measured in male golden hamsters during short-day-induced testicular regression and during testicular recrudescence following the transfer from short to long days. Serum FSH levels were maximally suppressed within 2 wk of transfer to short days. In contrast to FSH, irI alpha levels were not fully reduced until after 6 wk of exposure to short days, closely paralleling the timing of testicular regression. LH and T levels were also reduced within two 2k, with maximal suppression observed between 6 and 8 wk. Conversely, when males with regressed testes were transferred to long days, serum FSH rose to peak (25 ng/ml) levels by 3 wk and then declined to usual long-day levels. In contrast, serum irI alpha levels rose gradually, reaching adult long-day levels following 10 wk of exposure. Serum LH and T levels rose to peak levels between 5 and 8 wk before declining to adult levels. FSH, LH, and irI alpha levels were also measured after castration in male hamsters maintained on long or short days. Twenty-four hours after castration, levels of irI alpha were reduced in long-day males to levels comparable to those observed in castrated short-day males. Serum irI alpha levels respond slowly to abrupt changes in FSH levels after transfer to either long or short days, suggesting that testicular irI alpha secretion may not be directly and immediately influenced by circulating FSH levels in the hamster.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibin Pro-.ALPHA.C as the Marker of Testicular Function in the Stallion.

“…This has also been demonstrated for the males of other seasonal breeders such as sheep [15], monkeys [16] and hamsters [17]. The annual change in circulating inhibin pro-αC levels in the present study showed a positive correlation with ir-inhibin, testosterone and estradiol-17β indicating that circulating concentrations of inhibin pro-αC reflect the seasonal testicular function of stallions.…”

Is there a role for thyroid hormone on spermatogenesis?

“…In the immature rat testis, altered thyroid status has marked effects on Sertoli cells proliferative capacity and differentiation leading to modifications in testis size, Sertoli cells number and sperm production in adult life (Wagner et al, 2008). These T3 effects, initially described in rodents Joyce et al, 1993;Kirby et al, 1993), were subsequently identified in different vertebrate species (Jannini et al, 1995;Jansen et al, 2007;Kirby et al, 1996;Majdic et al, 1998;Matta et al, 2002;Weng et al, 2007).…”

Seasonal Changes in the Immunolocalization of Steroidogenic Enzymes in the Testes of the Japanese Black Bear (Ursus thibetanus japonicus).

“…The facility is located in the northern part of Japan (N 40°, E 140.4°) and consists of an outdoor run where the animals can The testis of seasonal breeders including bear species exhibits morphological differences throughout the year [6,7,11,14,19]. It has been reported that spermatogenic activity exhibited seasonal changes accompanied by changes in peripheral concentrations of testosterone [11,12,14,19,20,24,38]. These findings strongly suggest the occurrence of seasonal changes in testicular steroidogenesis in seasonal breeders such as bears.…”