AJP - Regulatory, Integrative and Comparative Physiology, Vol 258, Issue 2 376-R382, Copyright © 1990 by American Physiological Society

ARTICLES

Neuropeptide Y in the hypothalamus: effect on corticosterone and single-unit activity

H. E. Albers, J. E. Ottenweller, S. Y. Liou, M. D. Lumpkin and E. R. Anderson
Department of Biology, Georgia State University, Atlanta 30303.

The purpose of the present study was to determine whether neuropeptide Y (NPY) acts within the hypothalamic paraventricular nucleus (PVN) or the suprachiasmatic nucleus (SCN) to alter circulating levels of corticosterone and to evaluate the effects of NPY on the single-unit response of PVN and SCN neurons using the hypothalamic slice preparation. Blood levels of corticosterone were determined in groups of rats that received microinjections of NPY or saline (Sal) into the PVN or SCN. NPY injected into the PVN 4 h after light onset resulted in corticosterone levels of 13.15 +/- 2.18 (SE) micrograms/dl within 1 h, which were significantly higher than the corticosterone levels of 4.08 +/- 1.78 micrograms/dl seen in rats receiving Sal injections. In contrast, no significant differences were observed in circulating levels of corticosterone between groups of rats 1 or 4 h after NPY or Sal microinjection into the SCN. In the hypothalamic slice, NPY was found to produce primarily inhibitory responses in both SCN and PVN neurons. Forty-nine percent of the SCN units examined were inhibited. In addition, another 20% of the neurons tested in the SCN displayed excitation followed by more sustained inhibition. In the PVN, 45% of the units examined were inhibited by NPY, however, nearly 30% of the remaining neurons were significantly excited by NPY. In summary, NPY alters the electrical activity of both SCN and PVN neurons but appears to act only within the PVN to influence circulating levels of corticosterone. These and other data indicate that NPY acts as an important neurochemical messenger within several hypothalamic sites.

This article has been cited by other articles:

				G. Chen and A. N. van den Pol Multiple NPY Receptors Coexist in Pre- and Postsynaptic Sites: Inhibition of GABA Release in Isolated Self-Innervating SCN Neurons J. Neurosci., December 1, 1996; 16(23): 7711 - 7724. [Abstract] [Full Text] [PDF]

				K. Obrietan and A. N. van den Pol Neuropeptide Y Depresses GABA-Mediated Calcium Transients in Developing Suprachiasmatic Nucleus Neurons: A Novel Form of Calcium Long-Term Depression J. Neurosci., May 15, 1996; 16(10): 3521 - 3533. [Abstract] [Full Text] [PDF]