Norepinephrine release from PVN and lateral hypothalamus during perfusion with 2-DG or insulin in the sated and fasted rat

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Both insulin and 2-deoxy-D-glucose (2-DG) when given systematically to the rat modify the activity of noradrenergic systems in different regions of the animal's hypothalamus. The purpose of the present investigation was to ascertain whether the nutritional status of the animal would serve to influence the pattern of efflux of norepinephrine (NE) from sites in the hypothalamus perfused with either 2-DG or insulin. Permanent guide cannulae were first implanted stereotaxically above the paraventricular nucleus (PVN) or lateral hypothalamus (LH). Following recovery from surgery, each rat was either satiated with food or deprived of food for 20–22 hr with water always freely available. Then 0.1 μCi of [ 3H]-NE was micro-injected into the intended site of 3erfusion in a volume of 1.0 μl. After 15 min had elapsed, the site was perfused repeatedly with an artificial CSF at a rate of 20 μl/min. At the mid-point of successive 5.0 min perfusions, either 10 μg/μl 2-DG or 4.0 mU/μl porcine insulin was incorporated into the CSF perfusate. Thereafter, an additional set of 3–4 samples of perfusate was collected. When perfused in the PVN of the satiated rat, 2-DG significantly enhanced the efflux of [ 3H]-NE, whereas in the fasted animal insulin tended to suppress the output of the catecholamine. Conversely, at sites of perfusion in the LH, insulin evoked the release of [ 3]H-NE when the rat was fasted, whereas 2-DG tended to induce mixed effects on the release of [ 3H]-NE under both sated and fasted conditions. The results demonstrate that 2-DG as well as the pancreatic hormone can exert a unique action on the kinetics of noradrenergic activity in the hypothalamus which is solely dependent on the morphological site. Further, within each of the anatomical areas examined, the nutritional status of the rat, i.e., fasted or satiated, serves to determine the impact of these feeding factors on the release of NE.