The 5-HT1A agonist 8-OH-DPAT increases attachment maintenance but decreases suckling-related intake in 17-18-day-old rat pups

• Published in: Pharmacology, biochemistry and behavior Vol. 47; no. 1; pp. 133 - 139
• Main Authors: SPEAR, L. P, FRAMBES, N. A, GOODWIN, G. A, MOODY, C. A
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Science 1994
• Subjects: 8-Hydroxy-2-(di-n-propylamino)tetralin - pharmacology; Animals; Animals, Suckling; Behavioral psychophysiology; Biological and medical sciences; Dose-Response Relationship, Drug; Eating - drug effects; Female; Food Deprivation; Fundamental and applied biological sciences. Psychology; Male; Neurotransmission and behavior; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Rats; Rats, Sprague-Dawley; Serotonin Receptor Agonists - pharmacology; Sucking Behavior - drug effects; Weight Gain - drug effects; Suckling; Agonist; Feeding behavior; Rat; Rodentia; Weight gain; Young animal; Behavioral ontogeny; Ingestion; Vertebrata; Mammalia; S1A receptor; Subcutaneous administration
• ISSN: 0091-3057; 1873-5177
• DOI: 10.1016/0091-3057(94)90122-8

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.