Region-specific alterations in the concentrations of catecholamines and indoleamines in the brains of young and old F344 rats after L-deprenyl treatment

The effects of L-deprenyl, a monoamine oxidase-B (MAO-B) inhibitor, on the concentrations of norepinephrine (NE), dopamine (DA), 3,4-dihydroxyphenylac etic acid (DOPAC), homovanillic acid (HVA), serotonin (5-hydroxytryptamine) , and 5-hydroxyindoleacetic acid (5-HIAA) in medial basal hypothalamus (MBH ), substantia nigra (SN), striatum (Str), and nucleus accumbens (NAc) of yo ung (3 month) and old (21 month) male F344 rats were examined after a 7-day wash-out period following 1, 15, or 30 days of deprenyl treatment in young rats and a g-day wash-out period after a 10-week deprenyl treatment in old rats. The brain areas were microdissected and the concentrations of neurot ransmitters were measured by High Performance liquid chromatography with el ectrochemical detection (HPLC-EC). Deprenyl administration following the dr ug wash-out period increased the concentrations of DOPAC in the SN, Str, an d in the NAc of young rats but it was decreased in the NAc of old rats. The concentration of HVA was lower in the Str of young deprenyl-treated rats, and in the Str and NAc of old deprenyl-treated rats, but it was higher in t he SN of young deprenyl-treated rats. The concentration of B-HIAA was incre ased in the MBH, SN, and in the NAc of young deprenyl-treated rats, but it was decreased in the Str and NAc of old deprenyl-treated rats. The concentr ation of NE was increased in the MBH, SN, Str, and in the NAc of young rats treated with deprenyl and in the MBH of old deprenyl-treated rats, The con centration of 5-HT was increased in the SN of young deprenyl-treated rats. The concentration of DA increased in the Str of both young and old deprenyl -treated rats. We concluded that a drug wash-out period after deprenyl trea tment differentially affects the metabolism of catecholamines and indoleami ne depending on the region of the brain and that this effect may be due to variation in the kinetics of MAO inhibition. (C) 1999 Elsevier Science Inc.