Analgesic electrical stimulation of the hypothalamic arcuate nucleus: tolerance and its cross-tolerance to 2 Hz or 100 Hz electroacupuncture.
Focal electrical stimulation of the arcuate nucleus of the hypothalamus (ARH) for 5 min (1 session) produced a marked elevation of tail flick latency (TFL) to noxious heat in the pentobarbital-anesthetized rat. Repeated stimulation for a total of 11 sessions at 30 min intervals resulted in a gradual decline in the hypoalgesic action, and this tolerance may last for 7 days. Tolerance to the ARH analgesic stimulation reduced the analgesia produced by low (2 Hz) but not high (100 Hz) frequency electroacupuncture (EA); and tolerance to low frequency EA analgesia attenuated the ARH stimulation-produced analgesia without affecting high frequency EA analgesia. Alternatively, rats tolerant to high-frequency EA analgesia were still sensitive to either the ARH or low-frequency EA stimulation. These results suggest that the ARH stimulation and low-frequency EA administration produced analgesia via a common neural mechanism, supporting our hypothesis put forward previously that the ARH plays an important role in mediating low- but not high-frequency EA analgesia.
Wang
Q
Q
Department of Physiology, Beijing Medical University, People's Republic of China.
Mao
L
L
Han
J
J
D015670:Acupuncture Therapy; D000698:Analgesia; D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000033:anatomy & histology / Q000502:physiology* / Q000503:physiopathology; D004558:Electric Stimulation; D005260:Female; D006358:Hot Temperature; D010146:Pain / Q000503:physiopathology; D051381:Rats; D011919:Rats, Inbred Strains