Relationship between body and testis temperatures in the European hedgehog, Erinaceus europaeus, during hibernation and sexual reactivation

Abstract

Simultaneous telemetry of the body and testis temperatures of 8 hedgehogs was carried out during hibernation and during sexual reactivation in spring. Between October and January, when the testes were involuted, the body/testis temperature differential was variable, with mean daily testis temperatures up to 1 degrees C warmer than body temperatures. From mid-February onwards, when plasma testosterone approached maximal concentrations, mean testicular temperatures stabilized 1.4 +/- 0.2 degrees C below body temperatures. During spermatogenesis testicular temperature of hedgehogs was significantly lower than body temperature. Over the euthermic body temperature range of 34.7-36.2 degrees C, testicular temperatures varied from 34.0 to 34.9 degrees C. Only at body temperatures over 36.2 degrees C did testicular temperature reach 35 degrees C. During spermatogenesis hedgehog testis temperatures are similar to those of many scrotal mammals.

Testicular migration, spermatogenesis, temperature regulation and environment of the sheath-tail bat, Taphozous georgianus

“…Fowler & Racey (1987) reported that the testicular temperature of the ascrotal European hedgehog is also regulated within a narrower range than body temperature although they did not speculate on how this was achieved.…”

The reproductive cycle and determination of sexual maturity in male brown long‐eared bats, Plecotus auritus (Chiroptera: Vespertilionidae)

“…The inverse relationships between torpor and spermatogenesis have been explored in rodents and insectivores, and two separate explanations have been developed (e.g. Fowler & Racey, 1987;Darrow et al, 1988;Lee et al, 1990). First, torpor appears to suppress spermatogenesis, probably because of generally low metabolic rates and low body temperatures.…”

Seasonal endocrine cycles in the European hedgehog, Erinaceus europaeus

“…Therefore, most secretory activity must occur during spon¬ taneous arousals, which increase in frequency during the second half of hibernation (Kristoffersson & Soivio, 1964), especially since the pituitary-adrenal axis is known to be blocked during hibernation in the hedgehog (Hoo-Paris, 1971). That neuroendocrine activity during spontaneous arousal plays a part in the termination of hibernation (Wang, 1982) is supported by elevated pro¬ lactin values during winter, the reactivation of the gonads during the second half of hibernation (Fowler & Racey, 1987) and the observations of Saboureau et al (1984) who found that exogenous testosterone in autumn abolished hibernation in hedgehogs.…”

“…Plasma testosterone concentrations in male hedgehogs were determined using a heterologous, double-antibody, radioimmunoassay previously described by Fowler & Racey (1987). Minimum distinguishable testosterone levels were 005 ng/ml and intra-and inter-assay coefficients of variation were 10-8% and 13-4% respectively.…”