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Hypothalamic superfusion with histamine agonists and antagonists modifies the pressor response to hypothalamic
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|April 1, 1981
Summary
Histamine enhances the pressor response to posterior hypothalamic stimulation in cats. This effect is primarily mediated by histamine H2-receptors, as shown by experiments using specific receptor antagonists.
Area of Science:
- Neuroscience
- Pharmacology
- Physiology
Background:
- The posterior hypothalamus plays a role in cardiovascular regulation.
- Histamine is a neurotransmitter involved in various physiological processes.
Purpose of the Study:
- To investigate the effect of histamine on the pressor response elicited by posterior hypothalamic stimulation.
- To determine the specific histamine receptor subtype involved in this effect.
Main Methods:
- Anesthetized cats underwent push-pull superfusion of the posterior hypothalamus with cerebrospinal fluid (CSF).
- Electrical stimulation of the hypothalamus was performed.
- CSF containing histamine, dimaprit, or 2-methylhistamine was superfused.
- The effects of histamine receptor antagonists (metiamide and mepyramine) were assessed.
Main Results:
- Hypothalamic stimulation induced a pressor response.
- Histamine superfusion enhanced the pressor response in a concentration-dependent manner.
- Metiamide abolished the enhancing effect of histamine and the effect of dimaprit (an H2-receptor agonist).
- Mepyramine (an H1-receptor antagonist) had minimal effect on histamine's enhancement.
- 2-methylhistamine did not affect the pressor response.
Conclusions:
- Histamine increases the pressor response to posterior hypothalamic stimulation.
- The enhancing effect of histamine is predominantly mediated through histamine H2-receptors located in the posterior hypothalamus.