Central acetaldehyde supports appetitive conditioning in newborn rats.

MARCH S; CULLERÉ M; ABATE P; SPEAR N.E.; MOLINA JC

san antonio

Congreso; Scientific meeting of the Research Society on Alcoholism; 2010

Research Society on Alcoholism

Acetaldehyde is a biologically active metabolite of ethanol capable of producing ethanol-like effects such as hypothermia, motor stimulation, anxiolysis, conditioned-place preferences and conditioned taste aversions. It has also been shown that animals will self-administrate large amounts of this metabolite directly into the brain. Recently, using a surrogate nipple technique, Nizhnikov et al (2007) found that intracysternal administration of ethanol support appetitive conditioning in newborn rats. Moreover, this phenomenon is completely blocked when the central catalase system is inhibited through sodium-azide. The present study analyzed the reinforcing strength of different acetaldehyde doses centrally administered in newborn rats with or without prenatal exposure to moderate ethanol doses. During gestational days 17-20 (DG 17-20) dams were intragastrically administered with 0 or 2g/kg of ethanol. On DG20, cesarean-delivered pups were subjected to a pavlovian conditioning procedure in which lemon odor was associated with ethanol (100 mg%) or acetaldehyde (0; 0.0035; 0.007; 0.014 or 0.35 umol) administered in the cysterna magna (volume: 1ul). One hour later, pups were tested with an artificial nipple delivering water in the presence of lemon odor. Latency to grasp and total time attached to the artificial nipple, facial wipes and body weight gains were considered as dependent variables. Shorter latencies to grasp the artificial nipple, as well as longer attachment durations, were observed in pups administered with acetaldehyde (0.007 and 0.35 umol) and ethanol in comparison with vehicle administered pups. Prenatal treatment also exerted significant effects. Newborns prenatally exposed to ethanol exhibited reduced latencies to grasp the nipple, spent more time attached and displayed fewer facial wipes (a behavior which seems to indicate aversive responsiveness). According to the present results, central acetaldehyde is highly reinforcing in the newborn rat. Specifically, low (0.007 umol) and high (0.35 umol) acetaldehyde doses as well as ethanol served as unconditioned stimuli leading to the establishment of an appetitive associative memory.