K. Tsuiki et al., EFFECT OF HYPOTHALAMIC 5,7-DIHYDROXYTRYPTAMINE LESION ON THE ANTEROGRADE TRANSPORT OF SEROTONIN AS MEASURED WITH LABELED ALPHA-METHYL SEROTONIN, Neurochemistry international, 24(3), 1994, pp. 231-239
The anterograde axonal transport of serotonin along the medial forebra
in bundle (MFB) 5 days after unilateral dorsal hypothalamic 5,7-dihydr
oxytryptamine (5,7-DHT) lesion was examined in rat brain. Measurements
were done using in vivo synthesized radioactively labeled alpha-methy
l serotonin (used here as a serotonin tracer), from i.v. injected labe
led alpha-methyl-L-tryptophan, a substitute neurotransmitter and analo
g of serotonin. Data indicated that after destruction of the presynapt
ic terminals with 5,7-DHT, the rate of axonal transport of serotonin a
nd/or the rate of serotonin synthesis in the spared and/or damaged neu
rons was increased. The rate of serotonin anterograde transport on the
lesioned side was above 25 mm/d compared to 12.31 +/- 0.49 mm/d on th
e contralateral side and 12.13 +/- 0.44 mm/d in control (sham injected
) rats. The difference in rate between the lesioned and control rats w
as highly significant; P < 0.005 (two-tailed t-test). The amount of ne
urotransmitter anterogradely transported along the medial forebrain bu
ndle and/or synthesized in the neurons was 18.8 +/- 4.1 times greater
on the side of the 5,7-DHT hypothalamic lesion than that on the contra
lateral sides or that found in the saline-injected rats. There was no
difference in the radioactivity found on the left or right side of the
medial forebrain bundle in the rats 5 days after lesion in the rostal
midbrain with 5,7-DHT. Five days after the lesion there was also no d
ifference in the anterograde protein transport measured by stereotaxic
injection of [H-3]proline into the dorsal raphe.