Basic properties and annual changes of follicle‐stimulating hormone receptors in the testis of horseshoe bats, Rhinolophus ferrumequinum

Abstract

The unique reproductive patterns, delayed fertilization in females, and asynchrony between spermatogenesis and mating behavior in males are well documented in bats living in temperate latitudes. The present study was undertaken to examine follicle-stimulating hormone (FSH) receptors in the testis of bats, Rhinolophus ferrumequinum, during the annual reproductive cycle. Male bats were captured at natural roosting sites and testicular preparations were subjected to a radioligand binding assay for FSH receptors. The weight of paired testes increased considerably in the spermatogenic period and decreased from the mating to hibernation periods. Meiotic division in the testis was observed in the spermatogenic period but not the mating period. Serum testosterone concentrations increased in the spermatogenic period and rapidly decreased in the mating period. The binding of FSH was specific for mammalian FSHs and detected primarily in the testis. Scatchard plot analyses of the binding of FSH to bat testicular preparations showed straight lines, suggesting the presence of a single class of binding sites. The affinities (equilibrium association constant) of FSH receptors were consistent throughout the annual reproductive cycle. The specific binding per unit weight of testis and total binding in the paired testes were highest in the mating period and in the spermatogenic period, respectively, among reproductive periods. The accumulation of cyclic adenosine 3', 5'-monophosphate to FSH stimulation was higher in the spermatogenic period than in the hibernation period. These findings suggest that testicular function of bats is associated with seasonal changes in the number of binding sites, while the number per target cell and the activation of adenylate cyclase led by FSH-receptor complex considerably decreases in the hibernation period.

Living and Dying for Sex

“…In the long-lived bat for example, the GnRH/gonadotropins (proposed central mitogenic signaling factors) are briefly elevated only during the one time per year that they are fertile [Hayashi et al, 2002;Kawamoto et al, 2000]. This is also true for both sexes of the cockatiel which are exceptionally long-lived for their size, maximum lifespan 32 years.…”

Dose-dependent effects of perinatal hypothyroidism on postnatal testicular development in rat offspring

“…Morphometric analysis of seminiferous tubules was performed as described (Hayashi et al, 2002) with modifications as follows. Briefly, the transverse area and the perimeter of 50 random seminiferous tubule sections of bilateral testes in the control and 2.0 mg/kg/day groups were analyzed for each animal.…”

Testicular Development in Growth-Retarded Mice

“…The tissues were embedded in paraffin and sections cut at 3 µm thickness were stained with hematoxylin and eosin. Morphometric analysis of seminiferous tubules [6] was performed with modifications as follows. Briefly, the transverse area and the mean diameter [(maximal + minimal diameter/2)] of 50 seminiferous tubules of testes from normal and grt mice from bilateral testes were measured per animal.…”