Increased irritability: A permanent behavior change induced in the rat by intraventricular administration of 6-hydroxydopamine

✍ Scribed by K. Nakamura; H. Thoenen

• Publisher: Springer
• Year: 1972
• Tongue: English
• Weight: 784 KB
• Volume: 24
• Category: Article
• ISSN: 0033-3158
• DOI: 10.1007/bf00402530

✦ Synopsis

Intraventricular injection of 2 doses of 300 tzg of 6-hydroxydopamine (6-OHDA) into rats induced an increased reactivity to exogenous (non-painful) stimuli. This increased irritability lasted more than 4 months (the longest period studied) and consisted of crying, hissing, urination, defecation, standir g in an upright posture, biting and panic jumping. The degree of irritability was inversely correlated with the level of brain norepinephrine (NE). The uptake of atI-NE into all brain regions studied was decreased after administration of 6-0ttDA. The rate of aI-I-NE decay from the brain stem (hypothalamus, medulla-pons) was delayed I week and accelerated 9 weeks after 6-OItDA administration. The decay of atI-NE from the residual parts of the brain was enhanced both 1 and 9 weeks after 6-OI-IDA injection. Diazepam, chlordiazepoxide and meprobamate suppressed the increased irritability at doses which did not cause muscle relaxation. The normalization of the behavior produced by diazepam was accompanied by a normalization of the rate of aH-NE decay both in the brain stem and the residual parts of the brain. The neuroleptics chlorpromazine and haloperidol were effective in abolishing the increased irritability only at strongly sedative doses.