Effects of dopamine on snail neurones

• Published in: European journal of pharmacology 1995-09, Vol.283 (1), p.113-124
• Main Authors: Emaduddin, Muhammad, Liu, Guo Jun, Takeuchi, Hiroshi
• Format: Article
• Language: English
• Subjects: 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine - analogs & derivatives; 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine - pharmacology; Achatina fulica; Animals; Biological and medical sciences; Catecholamine; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; Dopamine; Dopamine - pharmacology; Dopamine Antagonists - pharmacology; Dopamine receptor, agonist, antagonist; Dose-Response Relationship, Drug; Electrophysiology; Freshwater; Fundamental and applied biological sciences. Psychology; Ionic mechanism; Membrane Potentials - drug effects; Neuron; Neurons - drug effects; Ouabain; Protein kinase inhibitor; Snail; Snails; Sulpiride - pharmacology; Time Factors; Vertebrates: nervous system and sense organs; Voltage clamp
• ISSN: 0014-2999; 1879-0712
• DOI: 10.1016/0014-2999(95)00301-Z

The pharmacological features of dopamine receptors in identifiable giant neurone types of a snail ( Achatina fulica Férussac) were studied. Under voltage clamp, two neurone types, LVMN (left ventral multiple spike neurone) and d-RPeAN (dorsal-right pedal anterior neurone), produced an inward current ( I in) in response to dopamine, (−)-noradrenaline and epinine, whereas v-LCDN (ventral-left cerebral distinct neurone) produced an outward current ( I out) in response to dopamine and epinine. Mammalian dopamine receptor agonists, fenoldopam (dopamine D 1-like receptor agonist), (±)-SKF 38393 (1-phenyl-2,3,4,5-tetrahydro-1 H-3-benzazepine-7,8-diol) (D 1-like), apomorphine (D 2-like), (−)-quinpirole (D 3 and D 4) and methylergometrine showed slight or no effect. (±)-SKF 83566 ((±)-7-bromo-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1 H-3-benzazepine) (dopamine D 1-like receptor antagonist) and (+)-UH 232 ( cis-(+)-5-methoxy-1-methyl-2-(di- n-propylamino)tetralin) (D 3 and D 2) non-competitively inhibited the I in of LVMN and d-RPeAN, but (±)-sulpiride (D 2-like) was without effect. In contrast, (±)-sulpiride competitively inhibited I out of v-LCDN, (+)-UH 232 non-competitively inhibited I out of v-LCDN but (±)-SKF 83566 was without effect. H-7 (1-(5-isoquinolinesulfonyl)-2-methylpiperazine) (non-selective protein kinase inhibitor) inhibited I in of LVMN and d-RPeAN, but did not affect I out of v-LCDN. Dopamine-induced I in was Na +-dependent; I out was K +-dependent. Ouabain did not affect these currents. We propose that the pharmacological features of Achatina neuronal dopamine receptors are not fully comparable to those of mammals, although intracellular signal transduction systems linked with dopamine receptors may similarly exist in different animal species.