Noradrenergic mechanism involved in the nociceptive modulation of hippocampal CA3 region of normal rats.
Norepinephrine (NE) is an important neurotransmitter in the brain, and regulates antinociception. However, the mechanism of action of NE on pain-related neurons in the hippocampal CA3 region is not clear. This study examines the effects of NE, phentolamine on the electrical activities of pain-excited neurons (PENs) and pain-inhibited neurons (PINs) in the hippocampal CA3 region of rats. Trains of electric impulses applied to the right sciatic nerve were used as noxious stimulation. The electrical activities of PENs or PINs in the hippocampal CA3 region were recorded by using a glass microelectrode. Our results revealed that, in the hippocampal CA3 region, the intra-CA3 region microinjection of NE decreased the pain-evoked discharged frequency and prolonged the discharged latency of PEN, and increased the pain-evoked discharged frequency and shortened discharged inhibitory duration (ID) of PIN, exhibiting the specific analgesic effect of NE. While intra-CA3 region microinjection of phentolamine produced the opposite response. It implies that phentolamine can block the effect of endogenous NE to cause the enhanced response of PEN and PIN to noxious stimulation. On the basis of above findings we can deduce that NE, phentolamine and alpha-adrenoceptor are involved in the modulation of nociceptive information transmission in the hippocampal CA3 region.
Department of Neurosurgery, Third Affiliated Hospital, Harbin Medical University, 150040 Harbin, Heilongjiang, China.
Hua
H
Jin
Central Laboratory of Blood Cancer, First Affiliated Hospital, Harbin Medical University, 150001 Harbin, Heilongjiang, China.
Yueqiu
Y
Teng
Department of Neurosurgery, Third Affiliated Hospital, Harbin Medical University, 150040 Harbin, Heilongjiang, China.
Xuexin
X
Zhang
Department of Neurology and Neurosurgery, Second Affiliated Hospital, Harbin Medical University, 150081 Harbin, Heilongjiang, China.
Chunxiao
C
Yang
Laboratory of Neural Electrophysiology, Department of Physiology, Harbin Medical University, 150081 Harbin, Heilongjiang, China. Electronic address: manyingxu@sohu.com.
Manying
M
Xu
Department of Neurology and Neurosurgery, Second Affiliated Hospital, Harbin Medical University, 150081 Harbin, Heilongjiang, China. Electronic address: lizhuangyang@sohu.com.
Lizhuang
L
Yang
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D056654:CA3 Region, Hippocampal / Q000378:metabolism / Q000503:physiopathology*; D004558:Electric Stimulation; D008297:Male; D009474:Neurons / Q000502:physiology; D059225:Nociception; D009638:Norepinephrine / Q000378:metabolism* / Q000494:pharmacology; D010146:Pain / Q000503:physiopathology; D010646:Phentolamine / Q000494:pharmacology; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000502:physiology
D000317:Adrenergic alpha-Antagonists; D009638:Norepinephrine; D010646:Phentolamine
Electrophysiology; Hippocampal CA3 region; Nociceptive modulation; Norepinephrine; Phentolamine