Role of the pineal gland and melatonin in the photoperiodic control of hypothalamic gonadotropin-releasing hormone in the male jerboa (Jaculus orientalis), a desert rodent.

The neuroendocrine mechanism underlying seasonal changes in gonadal activity of the jerboa, a desert hibernating rodent adapted to harsh climatic conditions, are poorly understood. We investigated the role of the pineal gland and melatonin in the photoperiodic control of hypothalamic gonadotropin-releasing hormone (GnRH). Intact and pinealectomized male jerboas were subjected to short photoperiod, while others were kept under long photoperiod and injected daily with melatonin or vehicle.