Impairment of spatial learning following preweaning cocaine exposure in the adult rat.

The present investigation focuses on learning and working memory capabilities of adult male and female Sprague-Dawley rats that were exposed to either cocaine (50 mg/kg/day sc) or distilled water during infancy (postnatal days 11-20). Learning and memory were assessed at 4 months using the eight-arm radial maze. Training was carried out in three phases in order to separate procedural learning from spatial capacity. Once criterion (entering at least seven arms without repeating arms for four out of five trials) was achieved in the first training room (Room 1), testing was moved to a second room (Room 2) with unique visual cues and an identical maze. Upon reaching criterion in Room 2, animals were returned to Room 1 and examined again. Cocaine-pretreated rats were less accurate than vehicle-pretreated rats during the first 10 trials of training. During the first five trials in Room 2 cocaine-pretreated animals made more errors, and made errors earlier within trials, than the vehicle-pretreated animals. Upon return to Room 1, reliable Gender x Pretreatment interactions were found for errors and total arms entered. These data demonstrate that a brief period of postnatal cocaine exposure can impair spatial cognition in adulthood and tentatively suggest that females are more sensitive than males.

Differential behavioral responses to chronic amphetamine in adult male and female rats exposed to postnatal cocaine treatment.

The impact of cocaine exposure during development on behavioral sensitization as measured by locomotor activity and stereotypy following repeated intermittent administration of amphetamine is examined. Male and female Sprague-Dawley rats were exposed to cocaine at 50 mg/kg/day during postnatal days (PND) 11-20 and, as adults (PND193-212), were administered seven daily injections of 2.0 mg/kg amphetamine. Both locomotor activity and stereotypic behavior were assessed following the first and seventh injections. Control males and females showed sensitized behavior following repeated amphetamine injections with females showing greater locomotion while males showed increased stereotypy. Male rats pretreated with cocaine failed to develop sensitized locomotor or stereotypic responses following repeated amphetamine injections consistent with dampened D(1) receptor activity. Females pretreated with cocaine did not show a sensitized locomotor response but did display sensitization of stereotypy following repeated amphetamine administration. Thus, it appears that postnatal cocaine treatment produces differential effects on the circuits mediating sensitization behavior in male and female rats.

Effects of repeated GBR 12909 administration on brain stimulation reward.

Male rats were trained at three separate currents to bar press for intracranial self-stimulation. On days 1 and 15, all subjects were given 1-(2-bis(4-fluorophenyl)-methoxy)-ethyl-4-(3-phenylpropyl) piperazine, also known as GBR 12909 (10 mg/kg, i.p.), prior to test session. Between these days, the paired Chronic-before group was injected (every other day) with GBR 12909 prior to intracranial self-stimulation, while unpaired, Chronic-after group was given the drug just after the end of the session. A third group (Control) received saline injections (i.p.) 20 min following the session. Although GBR 12909 was found to be reward enhancing, neither sensitization nor tolerance developed to the rewarding and performance/motor effects regardless of the injection regimen. In addition, the rewarding effects of intracranial self-stimulation were found to be independent of both current and environment-specific pairing. The present data obtained for GBR 12909 agree with previous observations of the effects of repeated administration of drugs of abuse on intracranial self-stimulation.

Emotion regulation and parenting in AD/HD and comparison boys: linkages with social behaviors and peer preference.

Children's emotion regulation strategies and parenting responses in a family task that elicited frustration are investigated by comparing core attention-deficit/hyperactivity disorder (AD/HD) symptomatology, emotional reactivity, and emotional regulation in the prediction of social behaviors and peer social preference. Participants were boys, ages 6-12 years, either with AD/HD (n = 45) or without problem behaviors (comparison; n = 34). A high-aggressive subgroup of AD/HD boys showed a significantly less constructive pattern of emotional coping than did both a low-aggressive AD/HD subgroup of boys and nondiagnosed comparison boys, who did not differ. With statistical control of core AD/HD symptomatology, noncompliance in a naturalistic summer camp was predicted by boys' overall emotion regulation and three specific strategies (emotional accommodation, problem solving, negative responses) during the parent-child interaction. Emotional accommodation and negative responses to the frustration task also marginally predicted social preference at the camp. These emotion regulation variables outperformed emotional reactivity in predicting such outcomes. Some emotion-related parenting behaviors were associated with child coping in the task. We discuss the relationship of emotion regulation to core AD/HD symptomatology and emotional reactivity, and the role of parents' behaviors in influencing children's emotional responses.

What they want and what they get: the social goals of boys with ADHD and comparison boys.

Twenty-seven boys diagnosed with attention-deficit hyperactivity disorder (ADHD) and 18 comparison boys participated in a competitive tetradic interaction task. Boys were individually interviewed before the game about their goals for the interaction, and adult observers inferred boys' social goals from videotapes of the interaction. Social acceptance was determined by combining positive and negative sociometric nominations collected through individual interviews at the end of the summer research program in which the interaction was held. In their self-reports, ADHD-high aggressive boys prioritized trouble-seeking and fun at the expense of rules to a greater extent than did both ADHD-low aggressive and comparison boys. Observers judged ADHD-high aggressive boys to seek attention more strongly and seek fairness less strongly than of the other two groups. Self-reported goals of defiance and cooperation predicted boys' end-of-program social standing, even with interactional behaviors and subgroup status controlled statistically. Observer-inferred goals were differentially associated with social acceptance for ADHD and comparison boys, suggesting discontinuities in peer interaction processes. Differentiation of goals from behavior and the integral role of children's goals in peer acceptance are discussed.