Primary astrocyte cultures from neonatal rat brains show uptake of [3H]norepinephrine ([3H]NE). This uptake has a high-affinity component with an apparent Km of approximately 3 X 10(-7) M. At 10(-7) M [3H]NE both the initial rate of uptake and steady-state content of [3H]NE is inhibited by up to 95% by omission of external Na+. The Na+-dependent component of this uptake is totally inhibited by the tricyclic antidepressants desipramine (DMI) and amitryptyline with IC50 values of 2 X 10(-9) and 4 X 10(-8) M, respectively. Inhibition of [3H]NE uptake by DMI shows competitive kinetics. These characteristics are essentially identical to those found for high-affinity uptake of NE in total membrane or synaptosome fractions from rodent brains and suggests that such uptake in neural tissue is not exclusively neuronal.
Chronic deficiency of growth hormone was produced in rats by injecting highly specific antibodies against rat somatotropin during the first week of postnatal life. Antisera were prepared by immunizing adult rhesus monkeys with purified rat growth hormone. The rate of body and brain growth was significantly decreased when compared with controls injected with nonimmune serum, and 50-day-old animals showed a profound and apparently specific endocrine deficiency of pituitary growth hormone as measured by bioassay. Defective cerebral maturation was evidenced by a 70 to 80 percent decrease of myelin lipids, a 65 percent reduction of deoxyribonucleic acid, and a small but significant decline in ribonucleic acid. An abnormal accumulation of undifferentiated glia was seen in the subependymal zone in association with decreased amounts of stainable myelin in subcortical white matter. The data suggest that pituitary growth hormone and/or its secondarily induced trophic factor, somatomedin B, influences the maturation of neural cells by regulating the replication of glia and the subsequent differentiation of oligodendrocytes to form myelin.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.