DECREASED DOMINANCE IN A LIMITED ACCESS TEST BUT NORMAL MATERNAL-BEHAVIOR IN MICRENCEPHALIC RATS

Micrencephalic offspring produced by gestational treatment with the an timitotic compound methylazoxymethanol acetate (MAM) are remarkable fo r substantial preservation of function concurrent with severe neural s tunting. Altered behaviors in these micrencephalics, including light s hyness and response perseveration, are similar to those produced by fr ontal cortex lesions. Consistent with this, the frontal cortex is one of several regions severely stunted by gestational MAM treatment. Beca use the frontal,cortex has been implicated in rodent social behavior, maternal behavior in females and dominance in both sexes were assessed . Dominance was measured via water competition in 24-h water-deprived dyads (1 control and 1 MAM) matched for sex and body weight. Micrencep halic rats exhibited shorter drinking time than controls (males: 101 v s. 219 s, p < 0.001; females: 114 vs. 176 s, p < 0.03), indicating tha t micrencephalics were more submissive. For maternal behavior tests, m icrencephalic and central females were bred to control males and pup r etrieval was measured on postnatal days 3-13. Micrencephalic dams were unimpaired in any aspect of pup retrieval. Of 8 standard behavior mea sures used here and previously, access time in water competition tests produced the dearest differentiation between control and micrencephal ic rats. These studies indicate that at least one aspect of social dom inance in both sexes is severely reduced by MAM treatment while matern al behavior remains intact.