Hormonal and photoperiod-induced changes in testicular interleukin-1-like factor in bank voles, Clethrionomys glareolus.

Testicular interleukin-1-like factor (tIL-1) is a cytokine secreted presumably by Sertoli cells in several mammalian species. The function of this cytokine is unknown: tIL-1 may control meiosis, act as a mitogen for spermatogonia or have both of these functions. The present investigation was conducted to assess tIL-1 activity and its hormonal control in a seasonally breeding photoperiodic mammal during testicular maturation and photoperiod-induced regression. Testicular maturation in long photoperiod (20 h light:4 h dark) was accompanied by the appearance of tIL-1 activity at the age of 32-39 days which increased as full sexual maturity was reached. No significant tIL-1 activity was detected when pubertal development was inhibited or testicular regression induced by subjecting juvenile and adult bank voles to a short photoperiod (6 h light: 18 h dark) for 6 to 8 weeks. Administration of human chorionic gonadotrophin (hCG; 60 IU kg-1) increased tIL-1 activity in sexually mature as well as regressed testes. In the photoregressed voles FSH (1.2 U kg-1) administration, which induced a three-fold increase in testicular weight and stimulated spermatogenesis, did not induce detectable concentrations of tIL-1. Administration of FSH followed by hCG increased tIL-1 activity significantly in the atrophic testis, but this was probably due to hCG, since FSH treatment alone was without effect. In conclusion, in accordance with the proposed role of tIL-1 as a germ-cell mitogen and a meiosis-promoting factor, tIL-1 activity correlated positively with spermatogenic activity during testicular maturation and photoperiod-induced regression.(ABSTRACT TRUNCATED AT 250 WORDS)