title: Differential effects of forskolin and phorbol-13-myristate injected intrathecally or intracerebroventricularly on antinociception induced by morphine or beta-endorphin administered intracerebroventricularly in the mouse.
abstract: The effects of forskolin or phorbol-13-myristate (PMA) injected intrathecally (i.t.) or intracerebroventricularly (i.c.v.) on the inhibition of the tail-flick and hotplate responses induced by morphine or beta-endorphin administered i.c.v. were studied. Animals pretreated with forskolin (20 micrograms) i.t. for 10 min had an attenuated inhibition of the tail-flick response induced by i.c.v. administered morphine (2 micrograms) or beta-endorphin (1 microgram). However, i.t. pretreatment with PMA (100 ng) was not effective in reducing the inhibition of the tail-flick response induced by morphine or beta-endorphin administered i.c.v. In addition, i.t. pretreatment with either forskolin or PMA did not affect the inhibition of the hotplate response induced by morphine or beta-endorphin administered i.c.v. Forskolin pretreatment i.c.v. for 10 min attenuated the inhibition of the tail-flick and hotplate responses induced by i.c.v. administered morphine or beta-endorphin. However, i.c.v. pretreatment with PMA was not effective in reducing the inhibition of the tail-flick or hotplate responses induced by morphine or beta-endorphin administered i.c.v. Our results suggest that activation of adenylate cyclase located at both spinal and supraspinal sites appears to be involved in antagonizing antinociception induced by morphine and beta-endorphin administered supraspinally. However, spinal or supraspinal protein kinase C may not be involved in antagonizing antinociception induced by morphine or beta-endorphin administered supraspinally.
authors.affiliation: Department of Pharmacology, College of Medicine, Hallym University, Chunchon, Kangwon-Do, South Korea.
authors.forename: H W
authors.initials: HW
authors.lastname: Suh
authors.forename: D K
authors.initials: DK
authors.lastname: Song
authors.forename: Y B
authors.initials: YB
authors.lastname: Sim
authors.forename: K M
authors.initials: KM
authors.lastname: Chung
authors.forename: Y H
authors.initials: YH
authors.lastname: Kim
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000698:Analgesia; D000818:Animals; D005576:Colforsin / Q000008:administration & dosage / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D007276:Injections, Intraventricular; D007278:Injections, Spinal; D007700:Kinetics; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009020:Morphine / Q000008:administration & dosage*; D010147:Pain Measurement; D011493:Protein Kinase C / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000008:administration & dosage / Q000494:pharmacology*; D001615:beta-Endorphin / Q000008:administration & dosage*
chemical_list: D005576:Colforsin; D001615:beta-Endorphin; D009020:Morphine; D011493:Protein Kinase C; D000262:Adenylyl Cyclases; D013755:Tetradecanoylphorbol Acetate