ANTISENSE OLIGONUCLEOTIDE INHIBITION OF TRYPTOPHAN-HYDROXYLASE ACTIVITY IN MOUSE-BRAIN

To examine in vivo effectiveness of antisense oligonucleotides against tryptophan hydroxylase (TPH) mRNA, adult male swiss-NIH mice were imp lanted with in-dwelling cannula into the 4th ventricle and after recov ery infused with either antisense oligonucleotide to TPH, scrambled co ntrol oligo or saline vehicle for four consecutive days. An additional group of animals bearing cannula were injected a single time i.p, wit h the TPH inhibitor para-chlorophenylalanine (PCPA; 300 mg/kg). All an imals were sacrificed on the afternoon of the 4th day of treatment. TP H activity was measured by enzymatic assay and HPLC quantification of end-product,synthesis. There was a significant decrease (> 50%) in TPH activity in both the PCPA-treated and antisense-oligo infused animals compared to either scrambled-oligo or saline-infused subjects (ANOVA; P < 0.05). There was no difference between saline and scrambled oligo -infusion. In a separate group of animals treated in the same way, beh avioral tests were conducted on the afternoon of the 4th day. Two test s of anxiety, the hole-board apparatus and the elevated plus-maze, ind icated some significant effects of PCPA treatment and/or antisense oli go-infusion but confounding effects due to alterations in locomotion c ould not be ruled out. However, tests on a rotorod apparatus indicated that antisense oligo-infused animals retained good balance and coordi nation in that their performance significantly improved on the second test, as did that of scrambled-oligo infused animals. In contrast, PCP A-treated animals did not improve, suggesting that locomotor performan ce had been impaired. These data support the notion that antisense oli go blockade may offer advantages over pharmacological manipulations of enzyme activity.