Behavioral changes in juvenile rats after prenatal exposure to ethosuximide

A mouse model of early social interactions after prenatal drug exposure: a genetic investigation

The aim of the present study was to (i) characterise the mouse behavioural profile (particularly social interactions) during the preweaning period, (ii) assess the effects of prenatal exposure to an anticonvulsant drug widely used in clinical practice, (iii) examine possible genetic differences both in baseline behavioural profiles and in sensitivity to drug-induced effects. Following a balanced intra-strain fostering procedure, the offspring of C57BL/6J and CBA inbred mouse strains from mothers exposed during pregnancy to either phenobarbitone (PHB, 60 mg/kg) or vehicle (VEH) given intraperitoneally (IP) during days 10-16 of gestation, were observed for early social interactions in the home cage during the last part of the preweaning period (days 20 and 21). The behavioural repertoires of the two strains differed markedly, in that C57 pups were more involved in Play soliciting, Locomotor-rotational play, and in Maintenance activities, while CBA mice spent much more time being inactive or exploring the environment. C57 and CBA mice also differed in the sensitivity to PHB exposure. On the whole, time spent in Investigative/Affiliative behaviours was increased, while the frequency of Play soliciting patterns was reduced in PHB-treated mice. The treatment of the fostering mother had only negligible effects, suggesting that PHB-induced changes in behaviour were largely due to direct effects of the substance on the foetus. These results indicate that specific items of the preweaning behavioural profile, and particularly social interactions, are influenced by early PHB exposure, and that the responses are heavily affected by the genotype.

Functional effects of glucocorticoid exposure during fetal life

1. Pregnant rats were exposed to hydrocortisone in a dose of 10 mg/kg on days 9-11 or days 13-15 of gestation. The offsprings born to these mothers were observed for their behavioral development and the response to kainic acid during the infantile period. The response to kainic acid was assessed by the frequency of wet-dog shakes behavior and limbic seizures. 2. The growth rate in the infantile offspring of the 13-15dHc-F1 group showed a slight but significant decrease. 3. All the 13-15dHc-F1 rats exhibited the rearing activity in an open-field at 17 days of age, earlier than in the controls. 4. The ambulatory activity in the 9-11dHc-F1 rats showed a significant decrease at 15 and 17 days of age, whereas no change was shown in the 9-11dHc-F1 rats. 5. The frequency of the wet-dog shakes during the 60 minutes observation after the s.c. injection of 9 mg/kg kainic acid was significantly low in both the 9-11dHc-F1 and 13-15dHc-F1 groups as compared with that in the controls when tested at 25 days of age. The decrease in the response to kainic acid was slightly greater in the 9-11dHC-F1 rats. 6. The frequency of seizures with forelimb clonus and rearing during the 60 minutes observation in the 13-15dHc-F1 was less than that in the controls, whereas no significant difference in the frequency of seizures between the 9-11dHc-F1 and paired control groups was noted. 7. The second generation rats raised from the 9-11dHc-F1 rats by brother-sister mating showed a decrease in the frequency in the kainic acid-induced wet-dog shakes as shown in the F1 offspring. No change in the response to kainic acid was shown in the 13-15dHc-F2 rats.