William J. Jenkins

Critical periods for the effects of alcohol exposure on brain weight, body weight, activity and investigation.

Using an animal model of fetal alcohol syndrome - which equates peak blood alcohol concentrations across different developmental periods - critical periods for the effect of alcohol on brain weight, activity and investigative behavior were examined. The periods of alcohol exposure were from gestational day (GD) 1 through 10, GD 11 through 22, postnatal day (PD) 2 through 10, or all three periods combined. The critical period of alcohol exposure for an increase in activity in juveniles was GD 11 through 22. This pattern was not seen in the same animals in adulthood; instead, increases in both activity and investigation were seen in animals exposed from PD 2 through 10 and not seen in animals exposed during all three periods combined. Brain weight was reduced by alcohol exposure from GD 11 through 22, PD 2 through 10 and all three periods combined. The period from PD 2 through 10 was the only period when the brain weight to body weight ratio was reduced. In conclusion, exposure to alcohol during the periods in the latter half of gestation or early postnatal period seem to have the most deleterious effects on the brain, activity and investigation in the rat. In addition, the effects of alcohol exposure over both the prenatal and postnatal period cannot be easily predicted from the effects of shorter periods of exposure.

Dynamic increases in dopamine during paced copulation in the female rat

The role of dopamine in the rewarding aspects of sexual behaviour in female rats was investigated. This is a unique model because sexual behaviour is only rewarding when copulatory stimuli are experienced at the preferred rate of copulation for a female rat. In addition, increases in dopamine in the nucleus accumbens occur during sexual behaviour only when the female achieves this preferred rate of copulation. In this study, minute‐by‐minute changes in nucleus accumbens dopamine were monitored using in vivo microdialysis. We report here that extracellular dopamine in the nucleus accumbens increases before coital stimulation only when sexual behaviour is occurring under conditions that are rewarding to the female rat. We conclude that increases in dopamine in the nucleus accumbens are involved in anticipation, not consummation, of sexual behaviour in the female rat.