| 12885436 |
Castro L, Athanazio R, Barbetta M, Ramos AC, Angelo AL, Campos I, Varjao B, Ferreira H, Fregoneze J, de Castro e Silva E: Central 5-HT2B/2C and 5-HT3 receptor stimulation decreases salt intake in sodium-depleted rats. Brain Res. 2003 Aug 15;981(1-2):151-9.
In the present study, we investigated the participation of central 5-HT (2B/2C) and 5-HT (3) receptors in the salt intake induced by sodium depletion in Wistar male rats. Sodium depletion was produced by the administration of furosemide associated with a low salt diet. Third ventricle injections of mCPP, a 5-HT (2B/2C) agonist, at doses of 80, 160 and 240 nmol, promoted a dose-dependent reduction in salt intake in sodium-depleted rats. The inhibitory effect produced by central administration of mCPP was abolished by the central pretreatment with SDZ SER 082, a 5-HT (2B/2C) antagonist. Similar results were obtained with third ventricle injections of m-CPBG (80, 160 and 240 nmol), a selective 5-HT (3) agonist that also induced a dose-related decrease in salt intake in sodium-depleted rats. The central pretreatment with LY-278,584, a selective 5-HT (3) receptor antagonist, was able to impair the salt intake inhibition elicited by third ventricle injections of m-CPBG. Central administration of each one of the antagonists alone or a combination of both antagonists together did not significantly change salt intake after sodium depletion. On the other hand, the central administration of both mCPP and m-CPBG, in the highest dose used to test their effect on salt intake (240 nmol), was unable to modify blood pressure in sodium-depleted rats. It is concluded that: (1) pharmacological activation of central 5-HT (2B/2C) and 5-HT (3) receptors diminishes salt intake during sodium depletion, (2) an inhibitory endogenous drive exerted by central 5-HT (2B/2C) and 5-HT (3) receptors does not seem to exist and (3) the reduction in salt intake generated by the pharmacological activation of these central receptors is not produced by an acute hypertensive response. |
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