Effect of central tachykinins, alone and with angiotensin II, on drinking in pigs and goats.

Central administration of the tachykinins, eledoisin or physalaemin has been reported to produce significant water intake in pigeons but inhibition of stimulated drinking in rats. In this paper it is shown that high and low doses of these two tachykinins injected centrally in two much larger species, goats and pigs, did not produce any significant drinking. Furthermore, in pigs, physalaemin, but not eledoisin, attenuated AII stimulated drinking (576 +/- 64 ml AII alone, versus 456 +/- 131 ml AII + eledoisin, not significant, and 124 +/- 89 ml AII plus physalaemin, p less than 0.01, in the same 5 pigs) and also, especially at the higher doses, induced general locomotor activation. However, in goats neither tachykinin interfered with drinking induced by central injection of 300 ng AII. These results show that in pigs and goats the tachykinins, eledoisin and physalaemin, are not effective dipsogens and that one of the possible reasons for the inhibitory action of physalaemin on AII-induced drinking may be through the general locomotor activation and not through a direct effect on the central AII system.