Effects of intrahypothalamic administration of opioid peptides selective for mu-, kappa, and delta-receptors on different schedules of water intake in the rat.
The effects of opioid peptides selective for mu, kappa, and delta-opioid receptors were investigated on 3 different schedules of water intake in the rat: spontaneous, deprivational (12 h), and hypertonic saline-induced drinking. Peptides were injected into the paraventricular and supraoptic hypothalamic nuclei, D-Ala2-NMePhe4-Gly(ol)-enkephalin, a mu-selective opioid agonist, tended to increase water intake in non-deprived rats, but 0.01 and 0.1 microgram significantly decreased water intake for 45 min in deprived rats, and for up to 60 min in hypertonic saline-injected rats when injected into the paraventricular hypothalamic nucleus. The kappa-selective agonist, dynorphin A1-13 (0.1, 0.3, 1.0 and 3.0 micrograms)and the delta-selective agonist, [D-Pen2,L-Pen5]enkephalin (0.3 and 3.0 micrograms) did not affect spontaneous, deprivational or hypertonic saline-induced water intakes when injected into either the paraventricular or supraoptic hypothalamic nuclei. Thus, a mu-selective opioid peptide produced dose- and time-dependent effects on drinking that were pharmacologically and anatomically specific, and dependent upon the schedule of water intake.
D000818:Animals; D004327:Drinking Behavior / Q000187:drug effects*; D004399:Dynorphins / Q000494:pharmacology*; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D020881:Enkephalin, D-Penicillamine (2,5)-; D004745:Enkephalins / Q000494:pharmacology*; D008297:Male; D008845:Microinjections; D010446:Peptide Fragments / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000187:drug effects / Q000502:physiology*; D012462:Saline Solution, Hypertonic / Q000494:pharmacology; D013997:Time Factors
D004745:Enkephalins; D010446:Peptide Fragments; D011957:Receptors, Opioid; D012462:Saline Solution, Hypertonic; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; C026843:dynorphin (1-13); D004399:Dynorphins; D020881:Enkephalin, D-Penicillamine (2,5)-