CONICET | Buscador de Institutos y Recursos Humanos

Sensitivity to ethanols autonomic effects (e.g., changes in respiratory rate) has been proposed as a biological marker signaling predisposition for alcohol-related problems. Rats can learn about the odor of ethanol by associating it with an aversive stimulus and they have been observed to acquire information about ethanol postabsorptive effects. Detection of ethanols scent also takes place when rats are exposed to the drug in utero. The latter experience results in differential postnatal responsiveness to ethanols chemosensorial properties and increased affinity for ethanol intake. The present experiment assessed acute and conditioned effects of postnatal ethanol intoxication upon respiration rates and perception of ethanols odor cues in infant rats. On postnatal day 11 (P11), pups were exposed to an ethanol scent (15 sec on, 45 sec off) while experiencing the pharmacological consequences of ethanol (0.5 or 2.5 g/kg, i.g., paired group) or while sober (unpaired control group). Across procedures, breathing rates were measured by use of a plethysmograph. On P12 (testing phase) pups were assigned to two groups: untreated or treated with a similar ethanol dose as that received on P11. Testing was defined by sequential stimulation with ethanol odor and an alternative scent (vanilla). The main results were as follows: (a) Acute ethanol intoxication readily depressed respiration rates, (b) Pups treated with 0.5 g/kg on Ps11-12 showed signs suggesting the development of rapid tolerance to ethanols suppressive effect upon breathing rate, and (c) When tested under sobriety, pups given pairings between ethanol odor and postabsorptive consequences of the drug exhbited lower respiratory rates than unpaired controls. The latter result indicates the expression of a conditioned breathing response mediated by ethanol intoxication. In summary, it was observed that ethanol intoxication markedly affected respiratory function in the infant rat. Ethanol-mediated effects upon respiration rate were sufficient to support the acquisition of Pavlovian learning. In conjunction with previous studies (Molina et al., 2006; 2007) the present set of results indicate early sensitivity to ethanols motivational effects in preweanling pups.

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