Meeting Abstract

P3.101  Thursday, Jan. 6  Pharmacological Study of Serotonin Post-Synaptic Receptors of the Lateral Ciliated Cells of the Gill and Visceral Ganglia of Crassostrea virginica HERNANDEZ, A.*; BANDAOGO, Z.; CARROLL, M.A.; CATAPANE, E.J.; Medgar Evers College; Medgar Evers College; Medgar Evers College; Medgar Evers College catapane@mec.cuny.edu

Lateral cilia of gill of Crassostrea virginica are controlled by serotonergic–dopaminergic nerves from their visceral and cerebral ganglia. Serotonin (HT) and dopamine (DA) are the neurotransmitters that increase and decrease ciliary beating rates, respectively. We undertook a pharmacological study of the HT receptor types. HT receptor families are classified as HT1 – 7, with subtypes. All but HT3 are G protein metabotrophic; HT3 are iontotrophic. Beating rates of cilia were measured by stroboscopic microscopy of isolated gill preparations and VG-gill preparations in which the innervation of the gill by the visceral ganglia was kept intact. Agonists and antagonists of different receptor families were tested at the gill and visceral ganglia (10^-5 – 10^-3 M) to determine their efficacy in altering cilia beating rates. The agonists 5-carboxamidotryptamine, alpha methyl serotonin and BIMU8, were effective in mimicing HT. 1-(3-chlorophenyl)biguanide was not effective. The antagonists, methysergide, NAN-190, GR127935 and clozapine N-oxide blocked HT from exciting the cilia. NAN-190, GR127935 and clozapine N-oxide were slightly excitatory when applied to the gill or ganglia, but methysergide was not. Analysis of the receptor families and subtypes for the agonists and antagonists indicates that HT4 or HT7 receptors are present in the gill and visceral ganglia. Both are excitatory receptors which increase cAMP levels. The study also shows that this preparation is a good model for pharmacological studies of dopamine function as well as the pharmacology of drugs affecting biogenic amines in nervous systems.