Bradley PB, Griggs I.
“Actions of Serotonin and Related Substances on Single Neurons in the Brain”.
Advanc Biochem Psychopharacol. 1974;10:159-166.
|
Abstract
In a previous investigation (Boakes, Bradley, Briggs, and Dray, 1970) we studied the actions of three derivatives of lysergic acid on neurons in the medulla and pons of decerebrate cats, using the microiontophoretic technique. The three derivatives studied were lysergic acid diethylamide (LSD), methysergide (UML), and 2-bromo-LSD (BOL). Their effects were examined on neurons which showed consistent responses to iontophoretic applications of one or more excitant or depressant compounds: 5 - hydroxytryptamine (5-HT), norepinephline (NE), glutamate (G), D, L-homocysteic acid (DLH), glycine, y-aminobutyric acid (GABA), and acetylcholine (ACh). - It was found that applications of LSD for 5 min or more at 50 nA significantly reduced or completely blocked the excitatory effects of 5-HT on 970f the neurons tested. The excitatory actions of . iontophoretically applied 5-HT were also selectively antagonized by LSD (12 to 50 mcg/kg) given by intravenous injection. The inhibitory effects of 5-HT, and the effects, either excitatory or inhibitory, of ACh, glycine, GABA, and DLH were not affected by LSD; only one of ten NE excitations was reduced and no NE inhibitions were affected. These findings are summarized in Table 1. However, LSD did antagonize the excitatory actions of glutamate on neurons which were excited by 5-MT, but not on neurons which 5-HT inhibited. Thus, there seems to be a relationship between the excitatory actions of 5-HT and those of glutamate. Methysergide was less active than LSD as an antagonist of 5-HT excitation, only 500f 5-HT excitations being blocked. BOL blocked only 180f 5-HT excitations tested. LSD is the most potent hallucinogen known; methysergide has some LSD-like hallucinogenic
|
# |
Submit Comment |
|