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Evidence that NPY-containing neurons in the brainstem project into selected hypothalamic nuclei: implication in
A Sahu1, S P Kalra, W R Crowley
1Department of Obstetrics and Gynecology, University of Florida College of Medicine, Gainesville 32610.
Brain Research
|August 9, 1988
Summary
Bilateral neural transections increase feeding behavior sensitivity to neuropeptide Y (NPY). This is linked to reduced NPY levels in specific brain areas, suggesting brainstem NPY projections influence feeding responses.
Area of Science:
- Neuroscience
- Neuroendocrinology
- Behavioral Neuroscience
Background:
- Bilateral neural transections (NT) in the dorsal tegmentum increase food intake and responsiveness to neuropeptide Y (NPY).
- This heightened sensitivity may result from denervation-induced hypersensitivity in hypothalamic feeding centers.
Purpose of the Study:
- To investigate the effect of NT on NPY concentrations in seven neural sites in male rats.
- To test the hypothesis that altered NPY levels mediate increased NPY responsiveness after NT.
Main Methods:
- Bilateral neural transections (NT) were performed at the dorsal tegmentum of the mesencephalon in male rats.
- NPY concentrations were measured in seven neural sites two weeks post-NT using biochemical assays.
Main Results:
- NPY levels remained unchanged in the suprachiasmatic nucleus, arcuate nucleus, and ventromedial hypothalamus.
- NPY concentrations significantly decreased (50-60%) in the medial preoptic area, paraventricular nucleus, median eminence, and dorsomedial nucleus.
- These decreases suggest brainstem projections containing NPY and adrenergic transmitters innervate these hypothalamic nuclei.
Conclusions:
- NPY-containing neurons from the brainstem project to specific hypothalamic sites.
- Reduced NPY levels in areas like the paraventricular nucleus after NT may underlie the increased sensitivity to NPY-induced feeding.