title: The role of adrenergic and cholinergic receptors on the antinociception of sildenafil in the spinal cord of rats.
abstract: The role played by spinal adrenergic and cholinergic receptors in the antinociceptive effects of intrathecal sildenafil in formalin-induced nociception was examined. Intrathecal catheters were inserted into the subarachnoid space of male Sprague-Dawley rats, and nociception was assessed using the formalin test, consisting of a subcutaneous injection of 50μL of 5% formalin solution into the hind paw. We examined the effects of an alpha 1 adrenergic receptor antagonist (prazosin), an alpha 2 adrenergic receptor antagonist (yohimbine), a muscarinic acetylcholine receptor antagonist (atropine), and a nicotinic acetylcholine receptor antagonist (mecamylamine) on sildenafil-induced antinociception. Intrathecal sildenafil (3, 10, and 30μg) suppressed, in a dose-dependent manner, formalin-induced flinching during phases 1 and 2 of the test. Intrathecal sildenafil (30μg) could not show any effects against intrathecal prazosin (3μg), yohimbine (10μg), atropine (10μg), and mecamylamine (10μg) pretreatment during both phases of the formalin test. These results suggest that intrathecal sildenafil effectively attenuated the pain evoked by formalin injection. Additionally, spinal alpha 1, alpha 2, muscarinic and nicotinic receptors might play a role in sildenafil-induced antinociception.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Kwangju Christian Hospital, Gwangju, Republic of Korea.
authors.forename: Chen Hee
authors.initials: CH
authors.lastname: Park
authors.forename: Hyung Gon
authors.initials: HG
authors.lastname: Lee
authors.forename: Seong Heon
authors.initials: SH
authors.lastname: Lee
authors.forename: Cheol Won
authors.initials: CW
authors.lastname: Chung
authors.forename: Myung Ha
authors.initials: MH
authors.lastname: Yoon
mesh_terms: D000818:Animals; D008297:Male; D009619:Nociceptors / Q000187:drug effects* / Q000502:physiology; D010879:Piperazines / Q000494:pharmacology*; D011687:Purines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology*; D018341:Receptors, Adrenergic, alpha-2 / Q000502:physiology; D011976:Receptors, Muscarinic / Q000502:physiology*; D011978:Receptors, Nicotinic / Q000502:physiology*; D000068677:Sildenafil Citrate; D013116:Spinal Cord / Q000187:drug effects* / Q000502:physiology; D013450:Sulfones / Q000494:pharmacology*
chemical_list: D010879:Piperazines; D011687:Purines; D018340:Receptors, Adrenergic, alpha-1; D018341:Receptors, Adrenergic, alpha-2; D011976:Receptors, Muscarinic; D011978:Receptors, Nicotinic; D013450:Sulfones; D000068677:Sildenafil Citrate