Ontogeny of opiate binding sites in the hippocampus, olfactory bulb and other regions of the rat forebrain by autoradiographic methods.
The postnatal development of the distribution of opiate binding sites in the rat forebrain was studied by light microscopic autoradiography. [3H] dihydromorphine ([3H]DHM) was used to label receptors in the forebrain of neonates days 2, 6, 8, 12, 16 and 21 postpartum. The hippocampus of the 2-day-old rat was diffusely labeled by [3H]DHM. By day 8, autoradiographic grains had a different distribution and were now clustered around the pyramidal cells. By day 16, the adult distribution of opiate binding sites was established. These changes correlate with the development of this structure and suggests that these binding sites may be localized to inhibitory interneurons of the pyramidal cell layer. The appearance of specific binding sites in the stratum moleculare of the dentate gyrus at day 8 further correlates with the development of the granule cells and their dendritic processes. In the olfactory bulb, high levels of specific binding were seen in the external plexiform layer at day 2. This pattern gradually changed, so that in the adult, the binding sites were more enriched in the glomeruli and granule cell layer. These changes in the olfactory bulb may be related to the maturation of the tufted cells and granule cells. Other regions of the brain were also examined. Thus, the analysis of receptor binding in development can aid in the localization of receptors to specific neuronal elements.
D000818:Animals; D001345:Autoradiography; D002454:Cell Differentiation; D002540:Cerebral Cortex / Q000166:cytology; D003342:Corpus Striatum / Q000166:cytology; D004090:Dihydromorphine / Q000378:metabolism; D005917:Globus Pallidus / Q000166:cytology; D006624:Hippocampus / Q000166:cytology*; D008125:Locus Coeruleus / Q000166:cytology; D008297:Male; D009474:Neurons / Q000166:cytology; D009830:Olfactory Bulb / Q000166:cytology*; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000378:metabolism*; D013477:Superior Colliculi / Q000166:cytology; D013787:Thalamic Nuclei / Q000166:cytology
D011957:Receptors, Opioid; D004090:Dihydromorphine