Stone EA, Lin Y, Ahsan MR, Quartermain D. Alpha(1)-adrenergic and alpha(2)-adrenergic balance in the dorsal pons and gross behavioral activity of mice in a novel environment.
Psychopharmacology (Berl) 2005;
183:127-32. [PMID:
16193333 DOI:
10.1007/s00213-005-0171-8]
[Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2005] [Accepted: 08/12/2005] [Indexed: 10/25/2022]
Abstract
RATIONALE
Central alpha(1)- and alpha(2)-adrenoceptors in a number of different brain regions are known to have opposing actions on gross behavioral activity, with the former stimulating and the latter inhibiting activity. Therefore, blockade of alpha(1)-receptors may induce inactivity by leading to unopposed alpha(2) activity.
OBJECTIVE
The aim of this study was to test if central blockade of alpha(2)-receptor function restores behavioral activity in alpha(1)-receptor-blocked mice.
METHODS
Dose-response studies were undertaken on the effects of alpha(1)- and alpha(2)-agonists and antagonists microinjected into the dorsal pons on gross behavioral activity in a novel cage test.
RESULTS
The behavioral inactivity resulting from blockade of alpha(1)-receptors in the pons with the antagonist, terazosin, was reversed by either a low dose of an alpha(2)-antagonist, atipamezole, or a low dose of an alpha(2)-agonist, dexmedetomidine, but was exacerbated by a high dose of the alpha(2)-agonist.
CONCLUSION
The results support the hypothesis that blockade of alpha(1)-receptors in the dorsal pons of mice produces inactivity by causing unopposed activity of alpha(2)-receptors. This condition may be relevant to inactive states seen after stress or during depressive illness.
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