Neural pathway from the olfactory bulbs regulating tonic gonadotropin secretion

Removal of the olfactory bulbs of male golden hamsters results in a marked increase in tonic gonadotropin, prolactin and testosterone secretion which counteracts inhibitory effects of manipulations such as maintenance on shor t photoperiod, food restriction or treatment with gonadal steroids. The bul bectomy-induced increase in hormone secretion is interpreted to reflect a t onic inhibitory influence of the olfactory bulbs. This inhibition is not de pendent upon chemosensory stimulation and may be mediated by olfactory bulb fibers projecting through the lateral olfactory tract to or through the ol factory tubercle. This review will relate these studies conducted on hamste rs to results in other species, such as the rat, where the olfactory bulbs enhance serum gonadotropin levels. (C) 1999 Elsevier Science Ltd. All right s reserved.