CANNABINOID RECEPTORS IN DEVELOPING RATS - DETECTION OF MESSENGER-RNAAND RECEPTOR-BINDING

Despite a large body of research directed at assessing the effects of perinatal cannabinoid exposure, little is known about the development of the cannabinoid receptor. Recent advances, including the cloning of the cannabinoid receptor, have afforded us the opportunity to plot th e postnatal ontogeny of the cannabinoid receptor and its mRNA in whole brain using the methods of receptor binding and RNA blot hybridizatio n, respectively. Our results indicate that cannabinoid receptor mRNA i s present at adult levels as early as postnatal day 3. The B-max, on t he other hand, increases almost fifty percent with increasing postnata l age, while the affinity does not change. The Hill coefficients for a ll ages studied were approximately 1. These findings suggest the possi bility of a developmental progression for cannabinoid receptor develop ment with receptor mRNA appearing first, followed by a period of rapid proliferation of the receptors themselves.