Membrane-delimited proteolytic regulation of opioid receptors.

Prolonged exposure of opioid receptors to agonists leads to their regulation by the classical process of clathrin-dependent internalization, followed by their intracellular degradation (down regulation). We have previously shown that the opioid agonist etorphine induced an additional process of down regulation of mu-opioid receptors (MOR) that occurred in intact MOR-transfected HEK-293 cells, as well as in isolated membranes. In the present study we show that etorphine similarly down regulated rat kappa-opioid receptors (KORs), which do not undergo the classical process of internalization and down regulation.

Factors influencing weight changes in callitrichids at the Bronx Zoo.

Callitrichids are small monkeys with high metabolic rates who appear to be susceptible to spontaneous diseases and possibly to environmental changes creating challenges in maintaining them in captivity. This study investigates whether life events (i.e.