The ontogeny of the postingestive inhibitory effect of peptone in rats.
The ontogeny of the postingestive inhibitory control of intake by protein digestion products was investigated by administering gastric preloads of a peptone that was a hydrolysate of meat and that decreased intake in adult rats [Am. J. Physiol., Regul. Integr. Comp. Physiol. 276 (1999) R1623; Am. J. Physiol., Regul. Integr. Comp. Physiol. 277 (1999) R1144]. Gastric preloads of saline or peptone, or sham preloads were given 5 min before a 30-min, independent ingestion test in which pups had access to a sweet, high-fat milk diet. Preloads of isotonic peptone reduced intake significantly more than preloads of isotonic saline on postnatal day (P) 18, but not on P12. Pretreatment with the CCKA receptor antagonist devazepide (600 microg/kg ip) did not change the inhibitory effect of isotonic peptone. Thus, the inhibitory effect of peptone on P18 was apparently not mediated by endogenous CCK acting at CCKA receptors. In contrast to isotonic peptone, preloads of hypertonic peptone did not decrease intake more than preloads of hypertonic saline on P12, P18, or P24. We conclude that if the isotonic peptone used in these experiments is an adequate model of the digestion products of dietary protein at these postnatal ages, then the postingestive inhibitory control of intake by digestion products of dietary protein during independent ingestion appears between P13 and P18.
Weller
Aron
A
Developmental Psychobiology Laboratory,Department of Psychology and the Gonda (Goldschmied) Multidisciplinary Brain Research Center, Bar dIlan University, Ramat Gan 52900, Israel. weller@mail.biu.ac.il
Tsitolovskya
Ludmila
L
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D020109:Devazepide / Q000494:pharmacology; D004347:Drug Interactions; D004435:Eating / Q000187:drug effects*; D005247:Feeding Behavior / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006727:Hormone Antagonists / Q000494:pharmacology; D007552:Isotonic Solutions / Q000494:pharmacology; D008297:Male; D010461:Peptones / Q000494:pharmacology*; D019518:Postprandial Period; D051381:Rats; D017207:Rats, Sprague-Dawley; D012462:Saline Solution, Hypertonic / Q000494:pharmacology; D012528:Satiety Response / Q000187:drug effects / Q000502:physiology; D012965:Sodium Chloride / Q000494:pharmacology; D013997:Time Factors
D006727:Hormone Antagonists; D007552:Isotonic Solutions; D010461:Peptones; D012462:Saline Solution, Hypertonic; D012965:Sodium Chloride; D020109:Devazepide