THE EFFECT OF NEUROPEPTIDE Y ON SPIKE ACTIVITY OF NEURONS IN THE SUPRACHIASMATIC NUCLEUS OF RAT IN VITRO

In the experiments on sagittal hypothalamic slices of male Wistar rats, the effect of 10 nM neuropeptide Y on the electrical activity of the suprachiasmatic nucleus neurons and spike information coding parameters were studied. Applications of neuropeptide Y induced a reduction of action potential frequency in 35 of 81 tested neurons, in 8 cells an increase in the parameter was observed; the remaining 38 neurons did not change their spike activity level. The decrease in spike frequency generation by neurons of the suprachiasmatic nucleus accompanied by an increase in both entropy of interspike interval distribution and mutual information between adjacent interspike intervals. These suggest an increased irregularity of the later as well as an increased patterning of spike information induced by neuropeptide Y. The obtained data indicate the ability of neuropeptide Y to modulate a level of activity and influence a spike code in a relatively numerous population of neurons in circadian oscillator of the suprachiasmatic nucleus.