ISSN:
1432-1912
Keywords:
3H-Imipramine binding sites
;
5,7-Dihydroxytryptamine
;
6-Hydroxydopamine
;
Serotoninergic neurones
;
Noradrenergic neurones
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Chemical destruction of serotoninergic and noradrenergic neurones with 5,7-dihydroxytryptamine and 6-hydroxydopamine, respectively, was used to investigate whether high affinity 3H-imipramine, binding sites are located postsynaptically or presynaptically on the respective nerve fibres in the rat cerebral cortex and hypothalamus. 1. 5,7-Dihydroxytryptamine treatment resulted in a 96% decrease in the maximal number of high affinity 3H-imipramine binding sites (B max) in cortical membranes and in a slight decrease in K D. 3H-5-hydroxytryptamine uptake into cortical slices of these animals was reduced by 63%. 2. 6-Hydroxydopamine treatment, on the other hand, caused only a slight but significant loss of 3H-imipramine binding sites (-20%) of the cortex, which was of the same magnitude as the decrease, in 3H-5-hydroxytryptamine uptake, and, hence, could be attributed to a moderate degeneration of serotoninergic fibers in this group. 3. Combined administration of 5,7-dihydroxytryptamine and 6-hydroxydopamine caused a reduction in B max values by 93%. This decrease was not significantly different from the loss of binding sites in those animals, which were injected with 5,7-dihydroxytryptamine only. 4. In the hypothalamus only 5,7-dihydroxytryptamine but not 6-hydroxydopamine significantly reduced both 3H-imipramine binding to membranes and 3H-5-hydroxytryptamine uptake into slices. 5. The decrease in the number of 3H-imipramine binding sites paralleled the degeneration of serotoninergic rather than noradrenergic nerve terminals. K D values of the remaining high affinity binding sites were in the same range as controls. It is concluded, that high affinity 3H-imipramine binding sites are selectively located presynaptically on 5-hydroxytryptamine neurones.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00501311
Permalink
