Expression of cannabinoid receptors in human kidney

The presence of CB1 and CB2 cannabinoid receptors and their physiological role in the kidney has been described in animal models but not in humans. Our aim in this study was to evaluate the presence of these receptors in human kidney, adult and fetal. For this purpose, RT-PCR, western-blot and immunohisto-chemical assays were performed. RT-PCR confirmed the presence of CB1 receptor mRNA receptor and the absence of the CB2 receptor mRNA in adult and fetal kidney. Western-blot and immunohistochemical assays revealed the presence of the CB1 cannabinoid receptor protein, which displayed a similar distribution in fetal and adult kidneys. Proximal and distal convoluted tubule cells and intercalated cells in the collecting ducts showed marked positivity. Conversely, the CB2 cannabinoid receptor protein was consistently negative in all cases. Our data suggest a possible implication of the endocannabinoid system in the physiology and development of the human kidney.