Effect of agmatine on long-term potentiation in morphine-treated rats.
Agmatine is an endogenous amine derived from l-arginine that potentiates morphine analgesia and inhibits naloxone precipitated abstinent symptoms in morphine dependent rats. In this study, the effects of agmatine on long-term potentiation (LTP) in the lateral perforant path (LPP)-granule cell synapse of the rat dentate gyrus (DG) on saline or morphine-treated rats were investigated. Population spikes (PS), evoked by stimulation of the LPP, was recorded from DG region. Acute agmatine (2.5-10mg/kg, s.c.) treatment facilitated hippocampal LTP. Acute morphine (30mg/kg, s.c.) treatment significantly attenuated hippocampal LTP and agmatine (10mg/kg, s.c.) restored the amplitude of PS that was attenuated by morphine. Chronic morphine treatment resulted in the enhancement of hippocampal LTP, agmatine co-administered with morphine significantly attenuated the enhancement of morphine on hippocampal LTP. Imidazoline receptor antagonist idazoxan (5mg/kg, i.p.) reversed the effect of agmatine. These results suggest that agmatine attenuated the effect of morphine on hippocampal LTP, possibly through activation of imidazoline receptor.
Lu
Wei
W
Beijing Institute of Pharmacology and Toxicology, TaiPing Road 27, Beijing 100850, China.
Dong
Hua-Jin
HJ
Bi
Guo-Hua
GH
Zhao
Yong-Qi
YQ
Yang
Zheng
Z
Su
Rui-Bin
RB
Li
Jin
J
D000376:Agmatine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000818:Animals; D018891:Dentate Gyrus / Q000187:drug effects / Q000502:physiology; D004347:Drug Interactions; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology; D019329:Idazoxan / Q000494:pharmacology; D054755:Imidazoline Receptors / Q000819:agonists / Q000037:antagonists & inhibitors; D017774:Long-Term Potentiation / Q000187:drug effects*; D008297:Male; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D054755:Imidazoline Receptors; D000376:Agmatine; D009020:Morphine; D019329:Idazoxan