Gonadal influences on spinal cord and brain monoamines in male rats.

Concentrations of norepinephrine (NE), dopamine (DA), 3,4-dihydroxy phenylacetic acid (DOPAC), serotonin (HT) and 5-hydroxyindoleacetic acid (HIAA) were measured by high-performance liquid chromatography-electrical detection (HPLC-ED) in homogenates of lumbosacral spinal cord, mediobasal hypothalamus and cerebral cortex of male rats. The effects of castration and testosterone propionate (TP) (20 micrograms/day X 2 days) were compared. Castrated animals had the highest levels of DA and DOPAC in the cerebral cortex and NE, HT and HIAA in the spinal cord, as well as decreased hypothalamic DOPAC. Testosterone treatment returned spinal cord monoamine concentrations to intact control levels. These findings point to the spinopetal monoaminergic pathways as sensitive targets for androgen action.