Prejunctional and peripheral effects of the cannabinoid CB1 receptor inverse agonist rimonabant (SR 141716)

Abstract

Rimonabant is an inverse agonist specific for cannabinoid receptors and selective for their cannabinoid-1 (CB₁) subtype. Although CB₁ receptors are more abundant in the central nervous system, rimonabant has many effects in the periphery, most of which are related to prejunctional modulation of transmitter release from autonomic nerves. However, CB₁ receptors are also expressed in, e.g., adipocytes and endothelial cells. Rimonabant inhibits numerous cardiovascular cannabinoid effects, including the decrease of blood pressure by central and peripheral (cardiac and vascular) sites of action, with the latter often being endothelium dependent. Rimonabant may also antagonize cannabinoid effects in myocardial infarction and in hypotension associated with septic shock or liver cirrhosis. In the gastrointestinal tract, rimonabant counteracts the cannabinoid-induced inhibition of secretion and motility. Although not affecting most cannabinoid effects in the airways, rimonabant counteracts inhibition of smooth-muscle contraction by cannabinoids in urogenital tissues and may interfere with embryo attachment and outgrowth of blastocysts. It inhibits cannabinoid-induced decreases of intraocular pressure. Rimonabant can inhibit proliferation of, maturation of, and energy storage by adipocytes. Among the many cannabinoid effects on hormone secretion, only some are rimonabant sensitive. The effects of rimonabant on the immune system are not fully clear, and it may inhibit or stimulate proliferation in several types of cancer. We conclude that direct effects of rimonabant on adipocytes may contribute to its clinical role in treating obesity. Other peripheral effects, many of which occur prejunctionally, may also contribute to its overall clinical profile and lead to additional indications as well adverse events.