Regeneration of serotonergic fibers in the rat hypothalamus following unilateral 5,7-dihydroxytryptamine injection.
The time course of degeneration and regeneration of serotonin (5-HT) fibers in the rat hypothalamus was studied with 5-HT immunocytochemistry and [3H]5-HT uptake following unilateral injections of 5,7-dihydroxytryptamine (5,7-DHT) into the dorsolateral hypothalamus. Within 3 days of the lesion, 5-HT fibers in the ipsilateral hypothalamus were swollen and darkly stained for 5-HT. In the contralateral hypothalamus few swollen fibers were apparent and these were generally restricted to the area adjacent to the fornix. Swollen 5-HT fibers were evident in the ipsilateral hypothalamus 3-19 days post-lesion in the medial forebrain bundle (MFB) during which time there was a gradual decrease in their density. In the medial and periventricular areas of the ipsilateral hypothalamus there were essentially no 5-HT fibers 7-30 days post-lesion. Sprouting 5-HT fibers were observed 12-19 days post-lesion. Thirty days post-lesion the density of 5-HT fibers in the MFB appeared normal; however, medial and periventricular areas remained denervated. Fifty days post-lesion there was an apparent bilateral hyperinnervation in the lateral and dorsomedial hypothalamic areas of 5,7-DHT-injected animals as compared to sham-injected animals. The morphological data were paralleled by changes in [3H]5-HT uptake. Seven days post-lesion specific high affinity uptake was reduced to 27% of sham in the ipsilateral hypothalamus and to 53% of sham in the contralateral hypothalamus. By 50 days post-lesion, specific high affinity uptake of [3H]5-HT was 141% of sham in the ipsilateral hypothalamus and 96% of sham in the contralateral hypothalamus.
D015116:5,7-Dihydroxytryptamine / Q000633:toxicity*; D000818:Animals; D001369:Axons / Q000187:drug effects; D004102:Dihydroxytryptamines / Q000633:toxicity*; D007026:Hypothalamic Area, Lateral / Q000187:drug effects*; D008297:Male; D008474:Medial Forebrain Bundle / Q000187:drug effects; D009410:Nerve Degeneration / Q000187:drug effects; D009412:Nerve Fibers / Q000187:drug effects*; D009416:Nerve Regeneration / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism*; D013574:Synaptosomes / Q000187:drug effects
D004102:Dihydroxytryptamines; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin