Localization of cannabinoid receptor mRNA in rat brain

Abstract

Cannabinoid receptor mRNA was localized in adult rat brain by 35S-tailed oligonucleotide probes and in situ hybridization histochemistry. Labelling is described as uniform or non-uniform depending on the relative intensities of individual cells expressing cannabinoid receptor mRNA within a given region or nucleus. Uniform labelling was found in the hypothalamus, thalamus, basal ganglia, cerebellum and brainstem. Non-uniform labelling that resulted from the presence of cells displaying two easily distinguishable intensities of hybridization signals was observed in several regions and nuclei in the forebrain (cerebral cortex, hippocampus, amygdala, certain olfactory structures). Olfactory-associated structures, basal ganglia, hippocampus, and cerebellar cortex displayed the heaviest amounts of labelling. Many regions that displayed cannabinoid receptor mRNA could reasonably be identified as sources for cannabinoid receptors on the basis of well documented hodologic data. Other sites that were also clearly labelled could not be assigned as logical sources of cannabinoid receptors. The localization of cannabinoid receptor mRNA indicates that sensory, motor, cognitive, limbic, and autonomic systems should all be influenced by the activation of this receptor by either exogenous cannabimimetics, including marijuana, or the yet unknown endogenous "cannabinoid" ligand.

Comparative analysis of fatty acid amide hydrolase and cb1 cannabinoid receptor expression in the mouse brain: evidence of a widespread role for fatty acid amide hydrolase in regulation of endocannabinoid signaling

“…6F). CB 1 -immunoreactivity in the molecular layer is largely associated with the parallel fibers of granule cells, consistent with CB 1 mRNA expression in granule-cell somata (Matsuda et al, 1993). Fig.…”

GABAergic interneurons are the targets of cannabinoid actions in the human hippocampus

“…In situ hybridization studies indicate low to moderate CB1 expression levels in pyramidal cells, [25][26][27]29,46 but despite the extensive search and use of novel antisera recognizing both proposed splice variants of CB1, 39 neither the cell bodies and dendrites, nor the axon terminals of pyramidal cells were found to express this receptor. In contrast, this complete lack of immunostaining in pyramidal cells does not exclude the possibility that our antibodies could recognize only those cells, which express high levels of CB1.…”

“…4,31,38 In contrast, CB1 mRNA was only found in these principal cells at low levels, slightly above the background, or low to moderate levels in the aged human hippocampus. [25][26][27]29,46 In the present study, we aimed to identify the precise cellular expression pattern and the subcellular localization (final plasma membrane destination) of CB1 receptors, and to investigate cannabinoid effects on GABA release in the human hippocampus. …”

“…The hippocampal formation is one of the brain areas with the highest level of CB1 receptor expression. 18,26,29 In accordance, at the behavioral level, cannabinoids typically interfere with hippocampal functions, i.e. they disrupt memory consolidation and associations both in humans and animals.…”

Depression in Parkinson's disease is related to a genetic polymorphism of the cannabinoid receptor gene (CNR1)

“…25 High levels of mRNA of CB1 gene were found by in situ hybridization in the rat limbic system, linking CB1 activity with memory and emotions. 26 THC inhibits synaptic release of dopamine, 5-HT, GABA and noradrenaline. 27 It has been suggested that the THC inhibitory role on dopamine and serotonin systems may be the origin of the lack of motivation and depression symptoms in marihuana consumers.…”