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Neuropeptide Y increases the inhibitory effects of clonidine on potassium evoked3H-noradrenaline but not3H-5-hydroxytryptamine release from synaptosomes of the hypothalamus and the frontoparietal cortex of the male Sprague-Dawle
- Source :
- Journal of Neural Transmission; February 1989, Vol. 78 Issue: 1 p61-72, 12p
- Publication Year :
- 1989
-
Abstract
- Summary The release of<superscript>3</superscript>H-noradrenaline (<superscript>3</superscript>H-NA) and of<superscript>3</superscript>H-5-hydroxytryptamine (<superscript>3</superscript>H-5-HT) evoked by high-K<superscript>+</superscript> (15 mM) was studied in synaptosomes isolated from the hypothalamus and the frontoparietal cortex of the male Sprague-Dawley rat using a superfusion apparatus. Based on concentration-response curves obtained by analyzing the full-time course of the inhibitory effects of clonidine on<superscript>3</superscript>H-NA and on<superscript>3</superscript>H-5-HT release neuropeptide Y (NPY) (1 nM) was shown to significantly increase the ability of clonidine to inhibit<superscript>3</superscript>H-NA release in synaptosomes isolated from the hypothalamus and from the frontoparietal cortex. NPY (1 nM) alone had no effect on K<superscript>+</superscript>-evoked<superscript>3</superscript>H-NA release from these regions. In contrast, NPY (1 nM) did not modulate the inhibitory effects of clonidine on<superscript>3</superscript>H-5-HT release in the above mentioned regions. These results indicate that NPY can increase the sensitivity of the a2-autoreceptors belonging to hypothalamic NA and/or to adrenaline nerve terminals and to cortical NA nerve terminals, while the a2-heteroreceptors inhibiting<superscript>3</superscript>H-HT release in the same brain regions appear not to be regulated by high affinity NPY receptors. Thus, a2-autoreceptors and a2-heteroreceptors appear to be differentially controlled by high affinity NPY receptors at least with regard to regulation of<superscript>3</superscript>H-NA and<superscript>3</superscript>H-5-HT release, respectively.
Details
- Language :
- English
- ISSN :
- 03009564 and 14351463
- Volume :
- 78
- Issue :
- 1
- Database :
- Supplemental Index
- Journal :
- Journal of Neural Transmission
- Publication Type :
- Periodical
- Accession number :
- ejs15537845
- Full Text :
- https://doi.org/10.1007/BF01247114