Reduction of 1-methyl 1,2,3,4-tetrahydroisoquinoline level in substantia nigra of the aged rat.

The compounds 1,2,3,4-tetrahydroisoquinoline (TIQ) and 1-methyl-1,2,3,4-tetrahydroisoquinoline (1-MeTIQ) are endogenous in humans and rats. Whereas TIQ seems to have neurotoxicity, 1-MeTIQ has been described as having a protective effect. In this paper, we report the concentration of TIQ and 1-MeTIQ in two areas especially influenced by aging and Parkinson's disease, the substantia nigra (SN) and striatum (ST), of the rat at different ages. 1-MeTIQ and TIQ were detected in both structures using gas chromatography-mass spectrometry with the higher content of both being in the SN. During the aging process there is a significant decrease (50%) in 1-MeTIQ levels in the SN, but TIQ levels did not change significantly in either of the studied regions.