Gastric related properties of rat paraventricular neurons.

Central control of gastric acid secretion (GAS) was formerly attributed to specific neurons in the lateral hypothalamus (LHA), but the rostral part of the paraventricular nucleus (r-PVN) of the hypothalamus was shown to be another site that modulates central control of GAS. In the present study, the characteristics of 145 spontaneously firing r-PVN neurons were investigated in 22 rats. Discharges were: high frequency regular or irregular, low frequency regular or irregular. About half of the regular discharges were phasic. Electrical stimulation in the r-PVN evoked responses in 407 LHA units. Response latencies ranged from 4.7 to 78.1 msec; indicating mono- and polysynaptic, and myelinated and nonmyelinated fiber connections. Gastric related and non-related r-PVN neurons were observed. It was also shown, for the first time, that electrophoretic application of various chemicals, especially glucose, affected chemosensitive neurons in the r-PVN. PVN neuron responses to LHA repetitive stimulation were classified as excitatory (E), excitatory-inhibitory (E-I), I and I-E. PVN neuronal discharges might be modulated by gastric type LHA neurons. Electrophoretically applied norepinephrine (NE) increased PVN neuronal activity and suppressed GAS. Results suggest that rostral PVN neurons might affect LHA control of GAS, with NE as the probable transmitter or modulator.