Minipump clorgyline administration and CSF amine metabolites in unrestrained monkeys

The irreversible MAO-A inhibitor clorgyline was administered in doses of 0.5 mg/kg (N = 1), 1 mg/kg (N = 3), and 2 mg/kg (N = 1) to 5 young (age 5.5 to 23.9 months) pigtail (M. nemestrina) monkeys using a 28-day (Alza 2ML4) osmotic minipump. CSF MHPG, 5-HIAA, HVA, and plasma MHPG were measured before and at approximately weekly intervals after pump implantation. Implants were well tolerated. CSF MHPG decreased about 75%, 5-HIAA 30%, and HVA from 30-50% with a tendency to plateau by the second week. Plasma MHPG decreased to undetectable levels. The findings demonstrate that long-term inhibition of MAO-A can be produced in unrestrained monkeys by minipump administered clorgyline. There is an apparently greater effect on the norepinephrine system relative to the serotonin and dopamine systems.