Pineal serotonin is resistant to depletion by serotonergic neurotoxins in rats.

Administration of 3,4-methylenedioxymethamphetamine (MDMA) or para-chloroamphetamine (pCA) to adult rats is neurotoxic to serotonin (5HT) nerve terminals and cell bodies. MDMA (10 mg/kg) reduces 5HT levels in the frontal cortex, medial basal hypothalamus, and striatum acutely and 17 days after a series of multiple injections. The acute reductions occur within 1-2 hr after injection of doses greater than 3 mg/kg. A single injection of pCA reduces 5HT levels in the above mentioned brain regions as well as in the brain stem. However, none of these treatments are able to alter 5HT levels in the pineal gland. It appears that the pineal does not contain the 5HT reuptake system that is thought to be necessary for the neurotoxicity of MDMA and pCA.