Article date: September 1991
By: Helen C. Jackson, I.J. Griffin, D.J. Nutt, in Volume 104, Issue 1, pages 258-262
Idazoxan (1, 3, 10 mg kg−1, i.p.) produced a significant increase in food and water intake in freely feeding rats during the daylight phase.
The more selective and specific α2‐adrenoceptor antagonists, RX811059 (0.3, 1, 3 mg kg−1, i.p.) and RX821002 (0.3, 1, 3 mg kg−1, i.p.), did not produce hyperphagia in rats, however, the highest dose produced a significant increase in water intake.
The peripherally acting α2‐adrenoceptor antagonist, L‐659,066 (1, 3, 10 mg kg−1, i.p.), did not affect food intake in the 4 h following injection, but the highest dose (10 mg kg−1), produced a large increase in water intake.
These results indicate that α2‐adrenoceptor antagonists may increase water intake by a peripherally mediated mechanism.
The lack of effect of RX811059 and RX821002 on food intake contrasts with the large dose‐related increases induced by idazoxan and suggests that the hyperphagic effects of idazoxan are not due to α2‐adrenoceptor blockade but may instead reflect its affinity for a non‐adrenoceptor site, a property not shared by the other α2‐antagonists.
Idazoxan (1, 3, 10 mg kg−1, i.p.) produced a significant increase in food and water intake in freely feeding rats during the daylight phase.
The more selective and specific α2‐adrenoceptor antagonists, RX811059 (0.3, 1, 3 mg kg−1, i.p.) and RX821002 (0.3, 1, 3 mg kg−1, i.p.), did not produce hyperphagia in rats, however, the highest dose produced a significant increase in water intake.
The peripherally acting α2‐adrenoceptor antagonist, L‐659,066 (1, 3, 10 mg kg−1, i.p.), did not affect food intake in the 4 h following injection, but the highest dose (10 mg kg−1), produced a large increase in water intake.
These results indicate that α2‐adrenoceptor antagonists may increase water intake by a peripherally mediated mechanism.
The lack of effect of RX811059 and RX821002 on food intake contrasts with the large dose‐related increases induced by idazoxan and suggests that the hyperphagic effects of idazoxan are not due to α2‐adrenoceptor blockade but may instead reflect its affinity for a non‐adrenoceptor site, a property not shared by the other α2‐antagonists.
DOI: 10.1111/j.1476-5381.1991.tb12416.x
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