Effect of Alpha Adrenergic Drug on Serotonin Release in Rat Hippocampal Slices

Song, Yun Seob; Yim, Yong Soon; Seo, Byoung Wook; Kim, Min Eui; Park, Young Ho; Lee, Moo Sang; Choi, Hyung Ki; Ahn, Young Soo

Abstract

PURPOSE: Peripheral adrenergic nervous system controls the penile erection and alpha adrenoceptors greatly outnumber beta adrenoceptors. It is known that adrenaline has a facilitatory effect but serotonin has an inhibitory effect on sexual drive centrally. But few about the effect of central alpha adrenergic drug to the release of serotonin centrally are known. Major adrenergic and serotoninergic innervation is found at the hippocampus. This study was performed to investigate the effect of alpha adrenergic drugs on serotonergic nervous system in rat hippocampal slices.
MATERIALS AND METHODS
The hippocampus from the male rat brain was sliced. After 30 minutes` preincubation in the normal buffer, the slices were incubated for 20 minutes in a buffer containing 0.1 microM [3H]5-hydroxytryptamine(5-HT) for uptake, and washed. After administration of phenylephrine or clonidine, the release of [3H]5-HT into the buffer was measured and the radioactivities in each buffer and the tissue were 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 was obtained.
RESULTS
After administration of phenylephrine(10-5 M), clonidine(10-5 M), the values(mean+/-SE) were 133.4+/-7.3, 103.0+/-0.3 at 60 minutes and 128.8+/-4.6, 100.4+/-4.1(%) at 70 minutes compared to the values of control group, 96.6+/-1.9 % at 60 minutes and 89.6+/-2.3% at 70 minutes. The release of serotonin was increased significantly after administration of phenylephrine.
CONCLUSIONS
It is suggested that alpha-1 adrenergic drugs may increase the release of serotonin and therefore the integration of these two neurotransmitters may be considered.