G-protein mediated responses to localized serotonin application in an invertebrate photoreceptor.
A G-protein dependent serotonin (5-HT) receptor on B photoreceptors of Hermissenda crassicornis was investigated. Microapplication of 5-HT to the soma region, but not to the terminal branches, resulted in a rapid, biphasic depolarization with a slow time course of dissipation. The 5-HT-induced depolarization increased at hyperpolarized potentials, and exhibited a strong and complex sensitivity to external K+, but not Na+ or Ca2+. The 5-HT response, but not a cholinergically mediated intraphotoreceptor interaction, was abolished by intracellular injection of the G protein antagonist, GDP[beta S], although the response was unaffected by pretreatment with pertussis toxin. These results are discussed in terms of known 5-HT receptor subtypes, and the potential role of this receptor in activity-dependent forms of plasticity exhibited by these cells.
Rogers
R F
RF
Department of Psychology, Rutgers University, New Brunswick, New Jersey 08903, USA.
Matzel
L D
LD
D000200:Action Potentials / Q000187:drug effects; D000704:Analysis of Variance; D000818:Animals; D019204:GTP-Binding Proteins / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects; D008974:Mollusca / Q000502:physiology*; D009473:Neuronal Plasticity / Q000187:drug effects*; D017956:Photoreceptor Cells, Invertebrate / Q000187:drug effects*; D011985:Receptors, Serotonin / Q000187:drug effects*; D012701:Serotonin / Q000494:pharmacology*
D011985:Receptors, Serotonin; D012701:Serotonin; D019204:GTP-Binding Proteins