Serotonin involvement during in vitro conditioning of Hermissenda.
To determine if serotonin may be involved in associative conditioning-produced changes in the excitability and photoresponses of Type B photoreceptors, isolated nervous systems were exposed to an in vitro conditioning procedure in the presence or absence of drugs that alter normal serotonergic neurotransmission. Pairings of light and intracellular depolarization of a caudal hair cell (in vitro conditioning) produced a pairing-specific depolarization of Type B photoreceptors that was accompanied by an increase in resting input resistance. Treatment of nervous systems with pharmacological agents which disrupt 5-HT neurotransmission attenuated membrane potential and input resistance changes of Type B photoreceptors. These drugs included serotonin uptake inhibitors (imipramine, fluoxetine), a receptor antagonist (bufotenine), and a neurotoxin (5,7-dihydroxytryptamine; 5, 7-DHT). Yohimbine, an alpha 2-receptor antagonist, was without effect. These results, and those in the accompanying papers, suggest that serotonin modulates Type B photoreceptor excitability during associative conditioning.
Grover
L M
LM
Department of Psychology, Princeton University, NJ 08544.
Farley
J
J
Auerbach
S B
SB
D015116:5,7-Dihydroxytryptamine; D000200:Action Potentials / Q000187:drug effects; D000320:Adrenergic Fibers / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002027:Bufotenin / Q000494:pharmacology; D003214:Conditioning, Classical / Q000187:drug effects / Q000502:physiology*; D007099:Imipramine; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D008974:Mollusca / Q000378:metabolism / Q000502:physiology*; D010786:Photoreceptor Cells / Q000378:metabolism / Q000502:physiology*; D012701:Serotonin / Q000378:metabolism / Q000502:physiology*; D015016:Yohimbine / Q000494:pharmacology
D002027:Bufotenin; D015016:Yohimbine; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D007099:Imipramine