Effects of Neuropeptide Y on the Functional State of the Afferent Inputs from the Arcuate Nucleus to the Suprachiasmatic Nucleus in Rats in Vitro

Experiments on sagittal sections of rat hypothalamus using electrophysiological methods for constructing and analyzing peristimulus time histograms (PSTH) addressed the modulatory influence of 10 nM neuropeptide Y on the functional state of the afferent inputs to neurons in the suprachiasmatic nucleus from the hypothalamic arcuate nucleus. Statistically significant responses to stimulation of the arcuate nucleus were recorded in 24 of the 54 suprachiasmatic nucleus neurons tested. Eight neurons produced responses consisting of short-latency arousal, while responses in six consisted of short-latency inhibition and 23 neurons showed complex biphasic and triphasic responses with different combinations of arousal and inhibition. Neuropeptide Y induced qualitative changes in responses (with disappearance of the initial or appearance of new responses) in seven of the neurons initially responding to stimuli and one neuron initially not responding to stimulation of the arcuate nucleus. In addition, a number of responses to peptide consisted of changes in the latent periods and durations of responses. These results point to the ability of neuropeptide Y to modulate the functional state of the afferent inputs to the circadian oscillator of the suprachiasmatic nucleus from the hypothalamic arcuate nucleus, which plays an important role in controlling appetite and metabolism. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.