Microelectrophoresis of cholinergic and aminergic drugs on paraventricular neurons.

Moss, ROBERT L., I. URBAN, AND B. A. CROSS. Microelectrophoresis OJ cholinergic and aminergic drugs on paraventricular neurons. Am. J. Physiol. 223(Z) : 3 10-3 18. 1972.-Acetylcholine, monoamines, amino acids, and antagonistic agents were applied microelectrophoretically to cells in the paraventricular (PV) nucleus of the rabbit hypothalamus. Successful drug applications and extracellular recordings were made on 37 1 cells of which 255 were identified as neurosecretory cells by antidromic stimulation of the neurohypophysis. The remaining 116 cells, though located in the paraventricular nucleus, were not antidromically invaded, and were considered to be nonneurosecretory. Acetylcholine excited 91 y0 of the neurosecretory PV cells. When tested with noradrenaline 8391, of these cells displayed a pronounced inhibition. Opposite effects were observed for the nonneurosecretory PV cells, i. e., 767 o were inhibited by acetylcholine, and 81 7. excited by noradrenaline. In some cells, but not others, acetylcholine excitations were blocked by atropine or dihydro-p-erythroidine. Glutamate had a powerful excitant action, and in all PV cells tested y-aminobutyric acid was uniformly inhibitory. Dopamine and 5-HT had variable effects. The results are compatible with a functional role for both noradrenaline and acetylcholine in the synaptic regulation of cell activity in the PV nucleus of the hypothalamus.