A role of the thymus and thymosin- alpha 1 in brain NGF levels and NGF receptor expression

Using neonatal rats we investigated the role of the thymus and thymosin- alpha 1 (T- alpha 1) in brain NGF levels, NGF receptor (p75NGFr) expression, as well as the activity of choline acetyl transferase, a cholinergic enzyme regulated by NGF. It is shown that early postnatal thymectomy causes a decrease in NGF in the hippocampus and cortex and p75NGFr distribution in the basal forebrain cholinergic neurons (FBCN). Intracerebral T- alpha 1 injection in thymectomized animals induces a recovery, albeit not complete, of both NGF and p75NGFr. These findings indicate that thymectomy affects both the brain NGF producing and responding cells and that T- alpha 1 may be one of the thymic hormones involved in the regulation of cerebral NGF synthesis.