Effects of adrenocorticotropic hormone and electroacupuncture on formalin-induced NOS-positiTe neurons in the spinal cord of rats

AIM:To study the effects of adrenocorticotropic hormone(ACTH) and electroacupuncture (EA) on formalin-induced nitric oxide synthetase (NOS)-positive neurons increases in the spinal cord or rats.METHODS:ACTH was administered by intrathecal injection (i.t.)and EA stimulation on “jiaji” point was performed by 1 mA 50Hz,5mA 5Hz and 1mA 5Hz respectively.The NOS-positive neurons were assayed by NADPH-diaphorase histochemistry.RESULTS:The results showed that both ACTH(0.5u,i.t.)and EA stimulation (1mA 50Hz,5mA 5Hz,1mA 5Hz) on “jiaji” point 30min significantly reduced the formalin-induced NOS-ositive neurons in the rat dorsal horn.The combinative use of ACTH (0.5u,i.t.) and EA(1mA 5Hz) caused a more marked reduction of the numbers of NOS positive neurons than that of the single ACTH or EA.Those effects were partially reversed by pretreatment with either the substrate of NOS,L-arginine (10nmol,i.t.)or opioid antagonist naloxone(10g,i.t.).CONCLUSION:These results suggests that both ACTH and EA might inhibit the formalin-induced NOS-positive neurons increases and have a synergic effect acting via a different pathway.

AIM:To study the effects of adrenocorticotropic hormone (ACTH)and elec-troacupunctune (EA) on formalin-induced nitric oxide synthetase (NOS) -positive neurons increases in the spinal cord of rats. METHODS: ACTH was administered by intrathecal injection (i. t )and EA stimulation on 'jiaji' point was performed by 1 mA 50 Hz, 5 mA 5 Hz and 1 mA S Hz respectively. The NOS-positive neurons were assayed by NADPH-diaphorase histo-chemistry. RESULTS: The results showed that both ACTH (0. 5 u, i. t. )and EA stimulation (1 mA 50 Hz, 5mA 5 Hz, ImA 5Hz) on 'jiaji'point 30 nan significantly reduced the formalin-induced NOS-positive neurons in the rat dorsal horn. The combinative use of ACTH (0. 5 u, i. t, ) and EA(1 mA 5 Hz) caused a more marked reduction of the numbers of NOS positive neurons than that of the single ACTH or EA. Those effects were partially reversed by pretreatment with either the substrate of NOS, L-arginine (10 nmol, i. t. ) or opioid antagonist naloxone(10 g, i. t ). CONCLUSION: These results suggests that both ACTH and EA might inhibit the formalin-induced NOS-positive neurons increases and have a synergic effect acting via a different pathway.