The 5-HT1A agonist 8-OH-DPAT increases attachment maintenance but decreases suckling-related intake in 17-18-day-old rat pups.
Deprived and nondeprived preweanling (17-18 days of age) Sprague-Dawley rat pups were injected with 0, 0.03, 0.06, 0.1, or 0.5 mg/kg of the 5-HT1A agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) and observed in a suckling test using a milk replete anesthetized dam, with milk let-downs being intermittently precipitated via IV infusions of oxytocin. In experiment 1, the 0.5 mg/kg dose of 8-OH-DPAT was observed to increase the proportion of nondeprived animals which attached to a nipple; no dose effect was seen in deprived animals, who generally all attached. Deprived pups given the 0.5-mg/kg dose exhibited a lower frequency of nipple disattachment/reattachment following milk let-downs and had significantly lower percent body weight gains when compared with saline controls. In experiment 2a, the 0.5-mg/kg dose of 8-OH-DPAT was observed to decrease the overall incidence of nipple disattachment/reattachment as well as to suppress nipple shifting per se in both deprived and nondeprived 17-18-day-old rat pups; this dose also suppressed body weight gains in both the deprived and nondeprived pups. The suppression in weight gain by 8-OH-DPAT does not appear to be primarily related to a drug-induced reduction in nipple shifting. In experiment 2b, where pups were given access to only one nipple, an 8-OH-DPAT-related reduction in body weight gain was still evident. These experiments, which demonstrate that attachment maintenance and suckling ingestion are altered in opposite ways by 8-OH-DPAT, provide strong evidence that these two suckling-related phenomena are subject to different physiological controls.
Spear
L P
LP
Department of Psychology, Binghamton University, State University of New York 13902-6000.
Frambes
N A
NA
Goodwin
G A
GA
Moody
C A
CA
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology*; D000818:Animals; D000833:Animals, Suckling; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects*; D005260:Female; D005508:Food Deprivation; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D013391:Sucking Behavior / Q000187:drug effects*; D015430:Weight Gain / Q000187:drug effects
D017366:Serotonin Receptor Agonists; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin