De- and regeneration of the bulbospinal serotonin neurons in the rat following 5,6-or 5,7-Dihydroxytryptamine treatment

In an attempt to determine the conditions which permit central 5-HT neurons to respond to a chemical injury of their axons by sprouting and regeneration, the pattern and time-course of recovery of 5-HT concentrations and regrowth of bulbospinal 5-HT axons were evaluated in rats subjected to intraventricular treatment with either 75 μg 5,6- or 150 μg 5,7-DHT. While 5,6-DHT treatment is followed by a significant recovery of 5-HT concentrations in the telodiencephalon, brainstem and upper part of the spinal cord within 3 months, there is no significant restoration of the severely depleted 5-HT levels in the telodiencephalon and spinal cord, and only limited recovery in 5-HT content of the brainstem preparation after 5,7-DHT.