The authors report that the expression of a conditioned odor aversion is impaired in preweanling rats when they are conditioned on Postnatal Day 12 and tested under the influence of scopolamine hydrobromide (0.2 or 0.5 mg/kg, intraperitoneal) after a 48-hr, but not after a 2-hr, retention interval (Experiment 1). This effect of scopolamine is not dependent on maturation of the cholinergic system between Days 12 and 14 (Experiment 2), nor is it due to peripheral mechanisms (Experiment 3). When pups are reexposed to the unconditioned stimulus (footshock) before drug administration, performance on the 48-hr retention test is not impaired by scopolamine (Experiment 4). These findings demonstrate that the cholinergic system may be critical for the retrieval and expression of long-term or weak memories in young rats. However, the expression of active memories (recent or recently reactivated) may not be dependent on the cholinergic system to the same extent as is the expression of inactive memories.
The effects of exogenous and endogenous steroids on components of female sexual behavior of neonatal male and female rats were investigated. In Experiment 1, 4-day-old rats were treated with 0, 0.1, 1.0, 10, or 100 micrograms/10 g body weight estradiol benzoate (EB) and were tested 44 hr later. In Experiment 2, male rats castrated within 24 to 48 hr of birth were compared with sham operated controls and castrates given steroid replacement. The results indicated that most 6-day-old pups will display lordosis and ear wiggling; therefore, the display of these responses is not dependent upon exogenous steroids. However, a fine-grained behavioral analysis revealed that EB treatment increased the frequency, duration, and intensity of lordosis and the frequency of ear wiggling in infant females, and it increased lordosis duration in males. Castration of infant males decreased the likelihood that male infants would display lordosis, whereas testosterone replacement restored behavior to control levels. These data question the concept that organizational and activational actions of estrogens occur during completely separable times in development and should provide new insights into the development of estrogen receptor function and the process of sexual differentiation of brain and behavior.
Objective: Project Northland is an ongoing prevention trial with the objective of reducing underage drinking and related problems. Phase I focused on early adolescence and this study describes the multiple interventions, highlighting its parent components. Methods: A cohort design was used with sixth graders from 24 school districts (N = 2,35 1: 97% of the eligible population: 51.3% boys), randomly assigned to intervention or reference condition. Phase I ended in eighth grade (N = 1,901: 81% retention rate). Both demand and supply reduction guided the interventions. This study examined Project Northland's impact using MMPI-A scales assessing clinical problems related to adolescents' alcohol and other drug use (Alcohol/Drug Problems Proneness scale; Alcohol/Drug Problems Acknowledgement scale), as well as MMPI-A scales related to school functioning (Adolescent-School Problems Content scale: Adolescent-Low Aspirations Content scale) and family functioning (Adolescent-Family Problems Content scale). Results: Results showed significant reductions on the MMPI-A Proneness scale for those exposed to the interventions. The greatest program effects were among baseline nonusers of alcohol. Conclusions: Results suggest that the impact of Project Northland is not only on specifically targeted alcohol and drug use behaviors and their predictive factors, but also on intra-individual and familial factors generally considered precursors of more extensive problem behaviors and more resistant to change. Furthermore, the engaging home-based sixth-grade intervention, the Slick Tracy Home Team Program, is a promising population-based prevention approach that may generalize to other serious problems within a young person's family.
Background: The Russian-American Partners for Prevention was an adaptation and evaluation of the Slick Tracy Home Team Program which was developed in Minnesota in order to delay the onset of drinking. The Slick Tracy Home Team Program was the first intervention of Project Northland, a large 3 year community trial of the efficacy of a public health intervention for under age drinking. Methods: The programme was administered through schools, but involved parents using engaging and fun homework activities. The Russian version was implemented in fifth-grade classrooms in 20 Moscow schools with 1,212 students surveyed at baseline. Students were surveyed again after programme implementation (n=1,182), of whom 980 were present at baseline. Parents of 1,078 students were surveyed by telephone after programme implementation. Results: The results demonstrated the successful recruitment and retention of 20 Moscow schools in a research project, acceptability of programme materials in Russia, high participation rates, changes in students' knowledge about problems associated with under age drinking and some evidence about increases in parent-child communication about alcohol use. As in the USA, no changes in students' alcohol use rates were observed at the end of the first year of the 3 year programme. Conclusion: Russian youth, as compared to Americans, began drinking at earlier ages, received fewer prevention messages from their parents, and had fewer prevention programmes in school. The results suggested that carefully implemented and evaluated replications of the US Project Northland interventions might provide effective and appropriate school-based programmes for Russia.
Neonatally castrated (MNC) and control male rats (MC) and female rats treated neonatally with estradiol benzoate (FNE) and female controls (FC) were studied. In Exp. 1 spatial memory was assessed using a 12-arm radial maze. During acquisition, MC and FNE groups were more accurate in choice behavior than FC and MNC groups. In Exp. 2 the discriminative control exerted by different types of cues was evaluated. Alteration of the geometry of the room but not movable landmarks disrupted performance of MC and FNE groups. For the FC and MNC groups, alteration of either geometry or landmarks did not disrupt performance. In Exp. 3 the effect of a 15-min delay was determined. MC and FNE groups were more disrupted by a delay than MNC and FC groups. Together, these data suggest that early exposure to gonadal steroids (probably estradiol) improves acquisition of spatial tasks by reorganizing and simplifying associational-perceptual processes that guide spatial ability.
Six-day-old male and female rats display lordosis and ear wiggling in response to tactile stimulation of the flanks and rump, without priming by exogenous estrogen. The involvement of various brain regions in these behaviors, which resemble components of adult female sexual behavior, was examined by making acute transections along the neuraxis from the olfactory tract to the medulla in 6-day-old rats. Four to 5 hr after the transection procedure, pups were tested for lordosis and ear wiggling. Lordosis was severely reduced or eliminated in pups with cuts through the hindbrain or diencephalon (above the level of the mammillary bodies) but was relatively unaffected by cuts through the posterior hypothalamus and rostral tegmentum and by cuts rostral to the anterior hypothalamus. Ear wiggling was disrupted by transections throughout the hindbrain and was facilitated only in females by transections throughout the forebrain (anterior to the mammillary bodies). These data suggest that facilitation from the hypothalamus is required for lordosis in the infant rat and the forebrain inhibitory systems for ear wiggling are functional in female infants by 6 days of age. Similarities and differences between the neural control of lordosis and ear wiggling in infant and adult rats suggest that the infant sex-like behaviors may be precursors of adult female sexual behavior.
The assessment of stressful life events during adolescence is important to both research and clinical practice. Stressful events are studied to determine their etiological significance in physical and mental illnesses, and also their relevance in the clinical assessment of individual patients. In recent years, a number of self-report inventories of life events for adolescents have been developed, some very carefully, others as one-time endeavors. This article reviews these measures, with an emphasis on the conceptual and methodological issues which created problems in earlier inventories. These issues need to be considered when choosing an instrument to study or assess stressful life events in adolescents.
