Influência da pineal e do nervo óptico na lactação de ratos

Abstract

The circadian rhythm comprises cyclic functions important for the animal temporal orientation regarding the reproductive strategies to be adopted along of the year. The principal rhythm used for the synchronization with the environment is the light-dark rythm or photoperiod. One of major components oh this rhythm is the pineal gland, wich is responsible for the transduction of the photic simulus into the hormonal scretion of melatonin. Melatonin stimulates target organs such as the suprachiasmatic nucleus and the pituitary gland to send behaviour-synchronizing-neural and hormonal signals. wich synchonize the photoperiod-dependent-neural and hormonal signal, wich synchhronize the photoperiod-depend-reproductive behaviour. IN the present work, the study of light influence in the lactation behaviour and the post-natal development of Wistar rats (Rattus norvegicus, BERKENHOUT, 1769), offsprings was carried out, using mothers that had been submited procedures wich interfered with then perception to lighy. 20-day-pregnant Wistar rats, obtained fron the CBR vivarium of UFJF, underwent pinealectemy, section of optic nerve, pinealectomy and optic nerve section and constant exposure to light. The control animals inderwent simulated operations and another group of female rats fron the colory were kepty under normal conditions of case. The clinic maternal conditions, the maternal mortality indices and food consumption were analysed. The offsprings were weighed on the birth, 5, 14 and 25 days, and the deaths observed in these days were noted. Milk consumption on the 14 day was also analysed by comparison of body weight 30 min before and after feeding. The results indicate that the alteration of the maternal photoperiodicity affects the development of offsrings, increases the mortality rate among them and causes puberty delay.