OLFACTORY BULBECTOMY INDUCES REPRODUCTIVE RECRUDESCENCE IN GOLDEN-HAMSTERS ON SHORT PHOTOPERIOD

Olfactory bulbectomy results in a marked increase in gonadotropin secr etion and prevents the reproductive regression associated with short p hotoperiod when the olfactory bulbectomy is done before exposure to th e inhibitory photoperiod. The present study tested whether olfactory b ulbectomy would offset the influence of short photoperiod if done afte r the reproductive system had regressed. Adult golden hamsters Mesocri cetus auratus were divided into four groups: early sham (surgery at we ek -4); early olfactory bulbectomy (surgery at week -4); late sham (su rgery at week 14) and late olfactory bulbectomy (surgery at week 14). At t = 0, all golden hamsters were placed in a short photoperiod (L:D 10:14). Early olfactory bulbectomy prevented testicular regression; th e late olfactory bulbectomy group recrudesced much earlier than the sh am groups. These results indicate that the tonic inhibitory influence of the olfactory bulbs is required for initiation of short photoperiod induced testicular regression and is also essential for the maintenan ce of the regressed state.