pathetic Nervous System Activity in Adipose Tissues During Pregnancy and Lactation of the Rat

摘要

concentration and turnover of norepinephrine in white adipose and liver tissues were determined in pregnant, lactating, and age-matched virgin rats to elu- cidate the adaptations in sympathetic nervous system activity. In study 1, at d 18 of pregnancy and d 7 and 21 of lactation, animals were killed, and liver and cardiac perimetrial and retroperitoneal adipose depots were quick-frozen and then assayed for norepinephrine as a gross estimate of sympathetic innervation. In study 2, the same design was used to measure the turnover of norepinephrine as a measure of sympathetic activity. Animals were treated with alpha - methylparatyrosine, an inhibitor of norepinephrine synthesis, and killed at 0, 1.5, and 3 h after injection. In pregnant animals, basal norepinephrine concentrations were decreased compared with unbred controls in perimetrial and re- troperitoneal depots. By d 21 of lactation, all adipose depots from lactating animals had more norepinephrine than did controls. The turnover of norepinephrine de- creased in noncardiac adipose depots of pregnant ani- mals. By d 21 of lactation, norepinephrine concentra- tion was greater in all of the adipose depots than in controls. The turnover rate was faster in all adipose tissue depots but only significantly different in the car- diac depot. Sympathetic nervous activity in adipose tis- sue is diminished in pregnant rats, presumably to save energy for fetal growth and maternal fat storage. In late lactation, activity is increased, presumably to di- rect fatty acids away from adipose tissue towards milk production. The data from this study are consistent with the hapothesis that the sympathetic nervous sys- tem plays a role in the reguation of adipose metabolism in lactation.