Age-related loss of cannabinoid receptor binding sites and mRNA in the rat striatum.

Differences in the distribution of cannabinoid receptor (studied by receptor binding radioautography using the synthetic psychoactive cannabinoid ligand [3H]CP55,940) and its mRNA (studied by in situ hybridization histochemistry using oligonucleotide probes complementary to rat cannabinoid receptor cDNA) have been investigated in the rat striatum during ageing. The striata of old rats (24 months) show a 50% reduction in expression of cannabinoid receptors and mRNA levels when compared with young (3 months) equivalents. Thus, changes in cannabinoid receptor gene expression appear to be partially responsible for age-related loss of these receptors.