Effects of chronic antenatal and postnatal administration of narcotics on naloxone-induced anorexia in preweanling rats

Developmental consequences of fetal exposure to drugs: what we know and what we still must learn

Most drugs of abuse easily cross the placenta and can affect fetal brain development. In utero exposures to drugs thus can have long-lasting implications for brain structure and function. These effects on the developing nervous system, before homeostatic regulatory mechanisms are properly calibrated, often differ from their effects on mature systems. In this review, we describe current knowledge on how alcohol, nicotine, cocaine, amphetamine, Ecstasy, and opiates (among other drugs) produce alterations in neurodevelopmental trajectory. We focus both on animal models and available clinical and imaging data from cross-sectional and longitudinal human studies. Early studies of fetal exposures focused on classic teratological methods that are insufficient for revealing more subtle effects that are nevertheless very behaviorally relevant. Modern mechanistic approaches have informed us greatly as to how to potentially ameliorate the induced deficits in brain formation and function, but conclude that better delineation of sensitive periods, dose-response relationships, and long-term longitudinal studies assessing future risk of offspring to exhibit learning disabilities, mental health disorders, and limited neural adaptations are crucial to limit the societal impact of these exposures.

Naloxone decreases intake of 10% sucrose in preweanling rats

To investigate the role of opioids in the mediation of sucrose intake in the preweanling rat pup, we measured the effect of naloxone on intake of pups licking 10% sucrose from the floor of a beaker (independent ingestion test) and of pups ingesting 10% sucrose that was continuously infused through an anterior, sublingual oral catheter (oral catheter test). Pups were tested only once to eliminate the possible effect of test experience. Pups were tested in the second postnatal week (PN7, 9, 10, 11, and 14 days) with naloxone (1 mg/kg) or vehicle controls. Fourteen-day-old pups were also tested with 0.1 and 0.5 mg/kg. Naloxone began to be efficacious for inhibiting intake on PN10 in the oral catheter test and on PN11 in the independent ingestion test. On PN14, the inhibition of intake was dose related and naloxone was more potent for inhibiting intake in independent ingestion tests than in oral catheter tests. Naloxone not only decreased intake, it also decreased the incidence of licking, increased mouthing and resting, and had no significant effect on locomotion. The site of the inhibitory effect of naloxone on intake was in the central nervous system, presumably in the brain, because naloxonemethiodide, an analogue of naloxone that does not cross the blood-brain barrier, did not inhibit sucrose in either test. These results demonstrate that the intake of 10% sucrose depends on endogenous opioids as early as PN10 and that this opioid mechanism operates when pups have not had prior test experience and in a test (oral catheter test) where intake is not dependent on appetitive behaviors.

Opiates, endorphins, and the developing organism: a comprehensive bibliography, 1982-1983

A comprehensive bibliography of the literature concerned with opiates, endorphins, and the developing organism for 1982 and 1983 is presented. Utilized with a companion paper (Neurosci Biobehav Rev 6: 439-479, 1982) these articles cover clinical and laboratory references beginning in 1875. For the years 1982 and 1983, a total of 385 citations was recorded. A series of indexes accompanies the citations in order to make the literature more accessible. These indexes are divided into clinical and laboratory topics. The clinical section is subdivided into: age of subject examined, maternal aspects, the fetus, and the offspring. The laboratory section is subdivided into: type of opiate/endorphin studied, species utilized, and major subject areas explored.

Endogenous opiates: 1983

This paper is the sixth in an annual series of reviews of research involving the endogenous opiates, each installment being restricted to work published during the previous year. Although the early articles in the series attempted to be comprehensive and cover the complete range of research with the opiate peptides, in the last two years we have limited our coverage to non-analgesic and behavioral work due to the enormous number of articles published in the field. The specific areas discussed here include stress, tolerance and dependence, consummatory responses, other gastrointestinal functions, interactions with alcohol, mental illness, learning and memory, cardiovascular responses, respiratory effects, thermoregulation, neurological disorders, activity, and miscellaneous other topics. As in previous years, we have attempted to present a relatively complete review of the subjects covered only for the previous year and generally have not tried to evaluate their contributions relative to those of past years.