Pain
-
In order to clarify the central mechanisms of thermal hyperalgesia produced by peripheral nerve injury, Fos protein-like immunoreactive (Fos-LI) cells in spinal dorsal horn neurons were studied in rats with chronic constriction nerve injury (CCI) following graded thermal stimulation of the hind paw. The graded thermal stimuli (cold: 5, 10 and 15 degrees C, heat: 42, 46 and 54 degrees C) were applied to the plantar surface of the operated hind paw 14 days after CCI or sham operation, and the number of Fos-LI cells in the spinal dorsal horn was quantified. Many Fos-LI cells were expressed in the superficial laminae of the spinal dorsal horn both in sham-operated and CCI rats following thermal stimulation. ⋯ No distribution difference of Fos-LI cells was observed between CCI and sham-operated rats in laminae V--VI. Thus, in the spinal dorsal horn of the CCI rats, there was a selective increase in thermal stimulus-induced Fos-LI cells in the superficial dorsal horn after stimulating at near noxious threshold intensities and a non-selective increase in Fos-LI cells in laminae III--IV after both noxious and innocuous thermal stimuli. The increase of Fos-LI cells in the superficial laminae may be related to hypersensitivity to noxious stimuli while the increase of Fos-LI cells in laminae III--IV may be related to an increased sensitivity to both noxious and innocuous stimuli that leads to increased reflex activity following nerve injury.
-
Small-scale studies have suggested a large inter-individual variation in early postoperative pain after laparoscopic cholecystectomy, emphasizing the need for improved analgesic treatment and valid predictors. We investigated prospectively the association between a preoperative nociceptive stimulus by ice water (cold pressor test), neuroticism, dyspepsia, patient history of biliary symptoms, intraoperative factors, and demographic information in 150 consecutive patients undergoing uncomplicated laparoscopic cholecystectomy for their influence on early postoperative pain. During the first postoperative week patients registered overall pain, incisional, visceral, and shoulder pain on a visual analogue scale and verbal rating scale, and daily analgesic requirements were noted. ⋯ Incisional pain dominated in incidence and intensity compared with visceral pain, which in turn dominated over shoulder pain. In a multivariate analysis model, preoperative neuroticism, sensitivity to cold pressor-induced pain, and age were identified as independent risk factors for early postoperative pain. Our results suggest that future analgesic studies after laparoscopic cholecystectomy should focus on reduction of incisional pain.
-
This study investigated sex and age cohort differences in the subjective report of orofacial pain symptoms in a stratified sample of community dwelling adults. The subjects were 724 participants in the Florida Dental Care Study, a longitudinal study of oral health among dentate adults, age 45 and older at baseline. Pain prevalence and subjective ratings were assessed for a range of orofacial pain sites using a standardized telephone interview. ⋯ Few overall age effects were found, with the exception of higher prevalence of temperature sensitivity and pain when chewing in the 45--64-year-old group, compared to respondents in the 65+ age cohort. However, the most interesting finding was that when sex by age cohort comparisons were made, with the exception of painful oral sores, all significant differences in pain ratings were found within the 45--64-year-old cohort and not the 65+ group. This finding clarified inconsistencies found in earlier studies in the orofacial pain literature where sex differences in pain ratings were found in several adult samples of a wide range of ages but not in a sample of older adults.
-
Bee venom (BV) has traditionally been used in Oriental medicine to relieve pain and to treat inflammatory diseases such as rheumatoid arthritis (RA). While several investigators have evaluated the anti-inflammatory effect of BV treatment, the anti-nociceptive effect of BV treatment on inflammatory pain has not been examined. Previous studies in experimental animals suggest that the therapeutic effect of BV on arthritis is dependent on the site of administration. ⋯ Finally, injection of BV into the Zusanli acupoint resulted in a significantly greater analgesic effect on arthritic pain as compared to BV injection in to a more distant non-acupoint. The present study demonstrates that BV injection into the Zusanli acupoint has both anti-inflammatory and anti-nociceptive effects on Freund's adjuvant-induced arthritis in rats. These findings raise the possibility that BV acupuncture may be a promising alternative medicine therapy for the long-term treatment of rheumatoid arthritis.
-
We have examined the effects of a novel GABA(B) agonist, CGP35024, in models of chronic neuropathic (partial sciatic ligation) and inflammatory (Freund's complete adjuvant) pain in the rat, and its inhibitory action on spinal transmission in vitro. The effects of CGP35024 were compared with L-baclofen and gabapentin. CGP35024 and L-baclofen reversed neuropathic mechanical hyperalgesia following single subcutaneous or intrathecal administration, but did not affect inflammatory mechanical hyperalgesia. ⋯ In the isolated hemisected spinal cord from the rat, CGP35024, L-baclofen and gabapentin all inhibited capsaicin-evoked ventral root potentials (VRPs). CGP35024 and L-baclofen, but not gabapentin, also inhibited the polysynaptic and monosynaptic phases of electrically-evoked VRPs, as well as the 'wind-up' response to repetitive stimulation. These data indicate that CGP35024 and L-baclofen modulate nociceptive transmission in the spinal cord to inhibit neuropathic hyperalgesia, and that CGP35024 has a therapeutic window for antihyperalgesia over spasmolysis.