Effects of rolipram on induction of action potential bursts in central snail neurons.
Effects of rolipram, a selective inhibitor of phosphodiesterases (PDE) IV, on induction of action potential bursts were studied pharmacologically on the RP4 central neuron of the giant African snail (Achatina fulica Ferussac). Oscillations of membrane potential bursts were elicited by rolipram and forskolin. The bursts of potential elicited by rolipram were not inhibited after administration with (a) calcium-free solution, (b) high-magnesium solution (30 mM) or (c) U73122. However, the bursts of potential elicited by rolipram were inhibited by pretreatment with KT-5720 (10 microM). Voltage-clamp studies revealed that rolipram decreased the total inward current and steady-state outward currents of the RP4 neuron. The negative slope resistance (NSR) was not detectable in control or rolipram treated RP4 neurons. TEA elicited action potential bursts and an NSR at membrane potential between -50 mV and -30 mV. It is suggested that the bursts of potential elicited by rolipram were not due to (1) synaptic effects of neurotransmitters; (2) NSR of steady-state I-V curve; (3) phospholipase activity of the neuron. The rolipram-elicited bursts of potential were dependent on the phosphodiesterases inhibitory activity and the cAMP signaling pathway in the neuron.
Lin
Chia-Hsien
CH
Department of Pharmacology, College of Medicine, National Taiwan University, No.1, Sec.1, Jen-Ai Road, Taipei, Taiwan.
Lin
Pei-Jung
PJ
Chen
Yi-Hung
YH
Lin
Pei-Lin
PL
Chen
I-Ming
IM
Lu
Kuan-Ling
KL
Chang
Yu-Chi
YC
Tsai
Ming-Cheng
MC
D000200:Action Potentials / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D002227:Carbazoles / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D002490:Central Nervous System / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D004963:Estrenes / Q000494:pharmacology; D017952:Ganglia, Invertebrate / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D007211:Indoles / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D018408:Patch-Clamp Techniques; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010740:Phospholipases / Q000187:drug effects / Q000378:metabolism; D010727:Phosphoric Diester Hydrolases / Q000187:drug effects / Q000378:metabolism; D011758:Pyrroles / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D020889:Rolipram / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D012908:Snails / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology
D002227:Carbazoles; D004963:Estrenes; D007211:Indoles; D010726:Phosphodiesterase Inhibitors; D011758:Pyrroles; D011760:Pyrrolidinones; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D005576:Colforsin; C057416:KT 5720; D000242:Cyclic AMP; D010740:Phospholipases; D010727:Phosphoric Diester Hydrolases; D008274:Magnesium; D020889:Rolipram