Choline acetyltransferase activity in the nucleus tractus solitarius: regulation by the afferent vagus nerve

The influence of nodose ganglionectomy or transection of the peripheral branches of the afferent vagus nerve on choline acetyltransferase (ChAT) activity in the nucleus tractus solitarius (NTS) was studied. ChAT activity was reduced in the microdissected caudal and intermediate portions of the NTS in vagotomized as well as ganglionectomized rats. However, only the ganglionectomy resulted in the degeneration of medullary nerve fibers. These results suggest that the changes in ChAT activity in the NTS are independent of neuronal degeneration and may be due to transynaptic modulation of ChAT activity by afferent vagal impulses. The presence of ChAT in the sensory nodose projection to the NTS, however, cannot be ruled out.