Difference in Serotonin Release after Administration of the Various Catecholamines in Rat Hippocampal Slices

Song, Yun Seob; Kim, Min Eui; Park, Young Ho; Choi, Hyung Ki; Ahn, Young Soo

Abstract

BACKGROUND AND PURPOSE: Catecholamines have an effect on sexual drive. When the sympathetic nervous system is excited, norepinephrine is released from nerve terminals, epinephrine from the adrenal glands, and dopamine in the central nervous system. Serotonin has a central inhibitory effect on sexual drive. Major adrenergic and serotoninergic innervation is found in the hippocampus. This study was performed to investigate the differences in serotonin release from rat hippocampal slices in the central nervous system in response to various catecholamines.
MATERIALS AND METHODS
The hippocampus from the rat brain was sliced. After 30 minutes' incubation in normal buffer, the slices were incubated for 20 minutes in a buffer containing 0.1 micro M [3H]5-HT and then washed. After administration of norepinephrine (10-5M), dopamine (10-5M), or epinephrine (10-5M), the release of [3H]5-HT into the buffer was measured. The radioactivity in each buffer and tissue was counted, and the results were expressed as a percentage of the total activity. The value of released [3H]5-HT was expressed as percent of the value at 50 minutes when a steady state of [3H]5-HT release had been obtained.
RESULTS
After administration of norepinephrine, dopamine, and epinephrine, the values (mean +/- SE, %) were 115.7 +/- 2.3, 136.8 +/- 10.5, 107.4 +/- 7.7 at 60 minutes and 105.8 +/- 5.5, 140.7 +/- 7.7, 94.2 +/- 6.2 at 70 minutes vs. 96.6 +/- 1.9 at 60 minutes and 89.2 +/- 2.3 at 70 minutes for the control group. The release thus was increased significantly after administration of norepinephrine and dopamine, and the effect of dopamine was more significant than that of epinephrine.
CONCLUSIONS
Release of serotonin is increased by norepinephrine and dopamine. The effect of dopamine was more significant than that of epinephrine. Reciprocal increase in serotonin release after administration of catecholamines may be involved in their effect on sexual function.