Differential effects of p-chlorophenylalanine on indoleamines in brainstem nuclei and spinal cord of rats. II. Identification of immunohistochemically stained structures using computer-assisted image enhancement techniques.
Following intraperitoneal injection of p-chlorophenylalanine (PCPA, 400 and 600 mg/kg) on 3 consecutive days, the brainstem and lumbar cord of rats were removed, frozen-sectioned and immunohistochemically stained (PAP method) for serotonin (5-HT). Using computer-assisted image analysis, the density of 5-HT staining in control, 400 and 600 mg/kg PCPA groups was determined. The mean number of pixels (representing 5-HT staining) was determined in 6 areas in the brainstem containing 5-HT cell bodies (nuclei raphe pallidus, raphe obscurus, rostral and caudal raphe magnus, raphe dorsalis and paragigantocellularis lateralis) and in the dorsal and ventral spinal cord. The results suggest a differential depletion of 5-HT within brainstem nuclei following PCPA treatment in that the most marked dose-related reductions were observed in nucleus raphe obscurus and caudal nucleus raphe magnus. Furthermore, a computer program designed to isolate terminal structures in the spinal cord identified a differential depletion of 5-HT terminals in the dorsal horn versus the ventral horn. The present study describes 3 analytical approaches combining immunohistochemistry with the computer-assisted image analysis technique and allows comparison between groups of animals which received the same or different drug treatments.
D000818:Animals; D001933:Brain Stem / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010134:Fenclonine / Q000494:pharmacology*; D007150:Immunohistochemistry; D009928:Organ Specificity; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000276:immunology / Q000378:metabolism*; D013116:Spinal Cord / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
D012701:Serotonin; D010134:Fenclonine