Varlinskaya E I, Petrov E S, Cheslock S J, Spear N E
Department of Psychology, Binghamton University - SUNY, New York 13902-6000, USA.
Alcohol Clin Exp Res. 1999 Aug;23(8):1368-76.
Ethanol intake in the context of suckling may have distinct and potentially long-lasting consequences for further responsiveness to and acceptance of ethanol, compared to other, more indirect and less natural ways of ethanol exposure early in ontogeny.
Our findings presented in this paper show that a surrogate nipple technique can be used for the study of early ethanol intake in cesarean-derived rat pups tested before any suckling experience.
Neonatal rats attached to and voluntary ingested ethanol through the surrogate nipple as early as 4 hr after birth. Moderate concentrations of ethanol (2% and 5%, v/v) promoted substantial initial suckling behavior, including sustained attachment to the nipple. Higher concentrations (10% and 15%) were not effective in sustaining suckling. Females responded less positively to 10% ethanol than did males. High concentrations of ethanol were less effective in eliciting suckling behavior, probably due to the aversiveness of ethanol odor. However, when ethanol was presented in solution with milk, newborn pups attached to the nipple and ingested even 15% ethanol. Contamination of milk with 15% ethanol was more aversive for females than for males. Newborn rat pups demonstrated similar patterns of nipple attachment and ingestive behavior for 5% ethanol and milk. Initial experience with milk in the context of suckling did not prevent further voluntary ethanol ingestion from the same nipple; furthermore, initial exposure to 5% ethanol did not impair subsequent responsiveness to milk.
Gender differences in responsiveness or sensitivity to ethanol can be detected in rat pups as early as a few hours after birth. The results suggest a leftward shift in the dose-response curve for females compared with males, indicating that female neonates are more sensitive or more responsive than males to ethanol. The similarity of suckling behaviors produced by moderate concentrations of ethanol and milk suggests a certain unity in their reinforcing mechanisms in the context of the first suckling episode.
与个体发育早期其他更间接、更不自然的乙醇接触方式相比，哺乳期间摄入乙醇可能对日后对乙醇的反应性和接受度产生独特且可能持久的影响。
我们在本文中呈现的研究结果表明，替代乳头技术可用于研究剖宫产出生且在有任何哺乳经历之前接受测试的大鼠幼崽的早期乙醇摄入情况。
新生大鼠早在出生后4小时就通过替代乳头附着并自愿摄入乙醇。中等浓度的乙醇（2%和5%，v/v）促进了大量的初始哺乳行为，包括持续附着在乳头上。较高浓度（10%和15%）在维持哺乳方面无效。雌性对10%乙醇的反应不如雄性积极。高浓度乙醇在引发哺乳行为方面效果较差，可能是由于乙醇气味的厌恶感。然而，当乙醇与牛奶混合溶液呈现时，新生幼崽会附着在乳头上并摄入甚至15%的乙醇。15%乙醇污染的牛奶对雌性比雄性更具厌恶感。新生大鼠幼崽对5%乙醇和牛奶表现出相似的乳头附着和摄食行为模式。哺乳期间最初接触牛奶并未阻止随后从同一乳头自愿摄入乙醇；此外，最初接触5%乙醇并未损害随后对牛奶的反应性。
早在出生后几小时就能在大鼠幼崽中检测到对乙醇反应性或敏感性的性别差异。结果表明，与雄性相比，雌性的剂量反应曲线向左偏移，表明雌性新生儿比雄性对乙醇更敏感或反应性更强。中等浓度乙醇和牛奶产生的哺乳行为相似性表明，在首次哺乳过程中它们的强化机制存在一定的统一性。
