The antinociceptive effect of non-noxious sensory stimulation is mediated partly through oxytocinergic mechanisms.
The objective of the present study was to investigate whether oxytocinergic mechanisms may contribute to the antinociceptive effect of non-noxious, sensory stimulation. To test this hypothesis, oxytocin levels in plasma and cerebrospinal fluid (CSF) were measured in control rats as well as in rats exposed for 30 min to electro-acupuncture (2 Hz), thermal stimulation (40 degrees C) or vibration (100 Hz). All modes of stimulation induced significant elevations of oxytocin levels in plasma and/or in CSF, 30 or 90 min after the end of stimulation. Secondly, the antinociceptive effects of these treatments were investigated in the tail-flick test with and without prior administration of the oxytocin antagonist 1-deamino-2-D-Tyr-(OEt)-4-Thr-8-Orn-oxytocin (1 mg kg-1 i.p.). All three modes of stimulation caused a significant delay of the tail-flick latency to the same degree as that caused by injection of oxytocin 1 mg kg-1 i.p. (electro-acupuncture P < 0.01, thermal stimulation and vibration P < 0.05). In all cases, the delay was reversed by administration of the oxytocin antagonist (1 mg kg-1 i.p.). These findings suggest that analgesic effects induced by non-noxious sensory stimulation may, in part, be mediated through activation of oxytocinergic mechanisms.
Uvnäs-Moberg
K
K
Department of Pharmacology, Karolinska Institutet, Stockholm, Sweden.
Bruzelius
G
G
Alster
P
P
Lundeberg
T
T
D015670:Acupuncture Therapy; D000818:Animals; D006358:Hot Temperature; D008297:Male; D009132:Muscles / Q000502:physiology / Q000503:physiopathology; D010121:Oxytocin / Q000097:blood / Q000134:cerebrospinal fluid / Q000378:metabolism*; D010146:Pain / Q000097:blood / Q000134:cerebrospinal fluid / Q000503:physiopathology*; D010147:Pain Measurement; D011312:Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley; D014732:Vibration
D010121:Oxytocin