Rf. Rogers et Ld. Matzel, G-PROTEIN MEDIATED RESPONSES TO LOCALIZED SEROTONIN APPLICATION IN ANINVERTEBRATE PHOTORECEPTOR, NeuroReport, 6(16), 1995, pp. 2161-2165
A G-protein dependent serotonin (5-HT) receptor on B photoreceptors of
Hermissenda crassicornis was investigated. Microapplication of 5-HT t
o the soma region, but not to the terminal branches, resulted in a rap
id, biphasic depolarization with a slow time course of dissipation. Th
e 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 in
traphotoreceptor interaction, was abolished by intracellular injection
of the G protein antagonist, GDP[beta S], although the response was u
naffected by pretreatment with pertussis toxin. These results are disc
ussed 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.