We investigated whether photoperiodic information is transferred from mother to young and whether the pineal gland and its hormone, melatonin, are involved in this transfer in Mongolian gerbils. Adult female gerbils were paired with males and housed in photoperiods of 12L:12D or 8L:16D. Three groups of pregnant gerbils in each photoperiod were prepared: one group was the sham-operated control, one group consisted of pinealectomized gerbils, and one group consisted of pinealectomized gerbils that were treated with melatonin. Pinealectomy was performed before pairing the animals and melatonin injections were applied to the pinealectomized group from day 8 of gestation until parturition. On the day of parturition, the mother and young were transferred to an intermediate photoperiod (10L:14D). After weaning, body weight gain and gonadal development of the male young were measured every week over 8 weeks. Animals gestated and born to control and pinealectomized + melatonin injected mothers exposed to 12L:12D responded to 10L:14D as a short day; they had significantly (P < 0.05) smaller testes than animals born to pinealectomized mothers. Animals gestated and born to control mothers exposed to 8L:16D responded to 10L:14D as a long day; they had significantly (P < 0.05) larger testes than animals born to pinealectomized and pinealectomized + melatonin injected mothers. Body weights of the gerbils did not vary significantly among the groups (P > 0.05). These results are the first evidence that the photoperiod to which the mother is exposed during gestation affects the postnatal gonadal development of the young and the pineal gland and melatonin play an important role in the transmission of photoperiodic information in the Mongolian gerbil.
KARAKAŞ, ALPER and GÜNDÜZ, BÜLENT (2007) "Maternal Transfer of Photoperiodic Information Regulates the Postnatal Reproductive System Development of the Mongolian Gerbil (Meriones unguiculatus)," Turkish Journal of Biology: Vol. 31: No. 2, Article 5. Available at: https://journals.tubitak.gov.tr/biology/vol31/iss2/5