Neurotensin releases norepinephrine differentially from perfused hypothalamus of sated and fasted rat
Lee, T.F.; Rezvani, A.H.; Hepler, J.R.; Myers, R.D.
American Journal of Physiology 252(1 Pt 1): E102-E109
1987
ISSN/ISBN: 0002-9513 PMID: 3544861 Document Number: 289942
Bilateral guide tubes for push-pull perfusion were implanted stereotaxically in rats to rest permanently above one of several intended sites of perfusion, which included the paraventricular nucleus (PVN), ventromedial nucleus (VMN) and the lateral hypothalamic (LH) area. After endogenous stores of norepinephrine (NE) at a specific hypothalamic locus were radiolabelled by microinjection of 0.02 to 0.5 mu Ci [superscript 3H]NE, artificial cerebrospinal fluid was perfused at the site at 20 mu l/min during successive intervals of 5.0 min. When NT 0.05 or 0.1 mu g/ mu l (0.03 to 0.6 mM) was added to the perfusate, the peptide increased or reduced the local release of NE at 50% of the sites of perfusion. The effect of neurotensin (NT) on the characteristics of catecholamine efflux depended entirely on the state of hunger or satiety. That is, when NT was perfused in the fully satiated rat, NE release was increased within the PVN or VMN; conversely, NE release was inhibited in the LH. In rats deprived of food for 18 to 22 h, NT exerted an opposite effect on the activity of NE within the same anatomical loci in that the efflux of NE was increased in the LH but attenuated or not affected in the PVN of VMN.