Further studies on the neurochemical specificity of 6-hydroxydopamine as compared to radiofrequency lesions.
Despite the large volume of literature during the past 15 years addressing the problem concerning the neurochemical specificity of 6-hydroxydopamine (6-OHDA), there is still disagreement over this issue. While some claim that the catecholamine-specific effects of this drug can be maximized by controlling the dose injected, others claim that all doses of 6-OHDA produce non-specific damage (NSD), thereby contraindicating its use in experimental paradigms. In the present study, we examined the degree of neurochemical specificity of 6-OHDA by comparing the volume of proximal accumulation to that of NSD, produced by 6-OHDA (2 microliter of 8 micrograms/microliter) or radiofrequency (RF) lesions (60 degrees C for 50 s and 45 degrees C for 30 s), placed in the medial forebrain bundle. The volume of NSD and accumulation produced by 6-OHDA was significantly less than that produced by large RF lesions which had a similar effect on the gross behaviour of albino rats. Smaller RF lesions produced similar volumes of NSD but less amine accumulation than did 6-OHDA, and did so without affecting normal behaviour. The ratio of NSD to accumulation in 6-OHDA treated rats was 3/1, while large and small RF lesions produced a NSD/accumulation ratio of 15/1. The present study introduces a novel method of determining the degree of neurochemical specificity which can be achieved with 6-OHDA and reveals that it is several magnitudes more neurochemically specific than RF lesions.
D000818:Animals; D002395:Catecholamines / Q000378:metabolism*; D006892:Hydroxydopamines / Q000494:pharmacology; D008297:Male; D008474:Medial Forebrain Bundle / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D009434:Neural Pathways / Q000473:pathology*; D016627:Oxidopamine; D011846:Radio Waves; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D002395:Catecholamines; D006892:Hydroxydopamines; D016627:Oxidopamine