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Unlearned and learned effects of intra-hypothalamic cyclic AMP injection on feeding

journal contribution
posted on 2023-06-08, 20:09 authored by D A Booth
INJECTIONS of adrenergic drugs into the hypothalamus of the rat have a wide variety of effects on feeding. Depending on site of injection, dosage, the rat's hunger state, and the drugs' peripheral alpha or beta characteristics, food intake may be elicited1–7 or suppressed7–9, or reactions to particular tastes may be modified either directly10–12 or by associative learning13. Such effects have been thought to result from the action of the injected drugs on synaptic receptors that normally respond to endogenous catecholamines. Adrenergic drugs can have marked effects on brain glycogen, however, varying widely in time course and direction between drugs and doses14–17. Drug-induced glycogenolysis might appreciably increase or decrease the supply of glucose to neurones affected. The firing rates of some neurones in both the ventromedial and lateral regions of the rat hypothalamus are influenced by the local concentration of glucose18,19. Furthermore, many of these glucosensitive units are affected by amphetamine19, which increases the amount of noradrenaline at the synapse20, inhibits feeding when injected into the hypothalamus9, and facilitates feeding when injected either with propranolol into the lateral hypothalamus or by itself into the ventromedial hypothalamus6. Although it has yet to be proved that hypothalamic glucose-sensitive neurones control normal feeding, the question arises whether any of the effects of hypothalamic injection of adrenergic drugs on feeding arise from metabolic rather than synaptic action.

History

Publication status

  • Published

Journal

Nature: New Biology

ISSN

0090-0028

Publisher

Nature Publishing Group

Volume

237

Page range

222-223

Department affiliated with

  • Psychology Publications

Full text available

  • No

Peer reviewed?

  • Yes

Legacy Posted Date

2015-03-01

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