5-HT receptors on identified Lymnaea neurones in culture: pharmacological characterization of 5-HT2 receptors.
1. Pressure ejection techniques were used to investigate the identify of receptors mediating 5-HT (5-Hydroxytryptamine) effects on the serotonin-containing cerebral giant cells (CGCs) of the cerebral ganglia and some of their follower motorneurones from the buccal ganglia of Lymnaea stagnalis in culture. 2. The vertebrate 5-HT2 receptor agonist alpha-methylserotonin maleate (10(-4) M), inhibited most of the neurones inhibited by 5-HT (10(-3) M). Others were excited by both agonists. In cells where 5-HT failed to evoke any effects, the 5-HT2 agonist also lacked an effect. 3. Bath application of the 5-HT2 receptor antagonists ketanserin and methysergide (10(-4) M), not only blocked spike generation, but also reduced both the excitatory and inhibitory responses to both 5-HT and alpha-methylserotonin maleate, while the 5-HT3 antagonist MDL 72222 (10(-4) M) failed to block alpha-methylserotonin maleate effects. 4. At 10(-3) M, alpha-methylserotonin maleate increased the amplitudes of the hyperpolarizing responses in a dose-dependent manner. These responses were blocked by ketanserin (10(-4) M). 5. The above results suggest that 5-HT2 receptors are involved in the responses of the CGCs and the buccal motorneurones to 5-HT in Lymnaea stagnalis. The pharmacological characterization of these receptors indicates that the compounds that interact with the 5-HT2 receptors in mammals also interact with the 5-HT2 receptors in molluscs.
Walcourt-Ambakederemo
A
A
Department of Physiology, University of Leeds, U.K.
Winlow
W
W
D000818:Animals; D001921:Brain / Q000166:cytology; D002478:Cells, Cultured; D015726:Giant Cells / Q000187:drug effects; D008195:Lymnaea; D009046:Motor Neurons / Q000187:drug effects*; D011985:Receptors, Serotonin / Q000187:drug effects; D012701:Serotonin / Q000494:pharmacology; D012702:Serotonin Antagonists / Q000494:pharmacology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*
D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D012701:Serotonin