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Subarachnoid injection of salmon calcitonin does not induce analgesia in rats
PBR resulted in slight suppression of motor responses in addition to profound nociceptive suppression. Carbachol-produced analgesia (CPA) observed within PBR blocked supraspinally as well as spinally integrated responses normally elicited by either phasic or tonic noxious stimuli. Atropine sulfate, hut not mecamylaminc hydrochloride. significantly antagonized CPA. indicating that muscarinic receptors mediate this phenomenon. The opiate antagonist naloxone. systemically administered either prior to or after carbachol microin_jection. did not attenuate CPA. Microinjection of morphine into the sites from which CPA had previously been obtained did not produce significant effects on nociceptive responses. Thus opiate mechanisms appear not to be necessary either for the activation of this system or for the productit~n of the resultant analgesia. These findings indicate that the neural population examined in the present study is anatomically and pharinac~~logi~ally distinct from previously identified opiate-mediated pain inhibitory systems. Single nerve capsaicin: effects on pain and morphine analgesia in the formalin foot-flick
tests. - F.V. Abbott.
R.W. Grimes
and R. Melzack,
and
Brain Res.. 295 (1984)
77 - x4. Capsaicin is a neurotoxin that apparently produces a selective lesion of unmyelinated fibers which is associated with a loss of substance P in the skin nerves and dorsal horn of the spinal cord. This neural damage is also associated with decreased responsiveness to painful stimuli that varies with the route of administration of capsaicin and the age of the animal at the time of administratioll. ,4pplication of capsaicin to the sciatic nerve reduces responsiveness to pain in the foot-flick test which examines brief, threshold level pain. The purpose of the present study was to determine if a similar reduction occurs in the formalin test which examines suprathreshold, deep pain that persists for several hours. The sciatic nerve on one side in the rat was exposed and soaked for 15 min in a solution of capsaicin and the saphenous nerve was ligated and cut. The operated foot was tested for sensitivity to pain in the formalin and foot-flick tests 2 days to 12 weeks later both with and without morphine. The capsaicin treatment produced a substantial reduction in sensitivity to foot-flick heat pain at all times after surgery. In the formalin test, the effects were small and tended to suggest that the rats felt more rather than less pain. The capsaicin treatment markedly reduced the sensitivity of formalin test pain to morphine. This effect appeared about 1 week after surgery and persisted for 12 weeks. The results suggest that capsaicin-sensitjve uIl~nyelinated afferents play a role in the threshold level, non-damaging heat pain. but are not involved in pain resulting from tissue damage. However, these afferents appear to be important for the spinal action of morphine on this type of pain. Subarachnoid
injection of salmon calcitonin does not induce analgesia in rats. - Z.
Wiesenfeld-Hallin and A. Persson. Europ. J. Pharmacol., 104 (1984) 3755377. Calcitonin is a polypeptide produced in the thyroid gland of mammalian and non-mammalian species which causes hypocalcemia by inhibition of the release of calcium from bone. Clinically calcitonin is administered to treat Paget’s disease where bone turnover is enhanced. It has been proposed that calcitonin occurs in the
209
central nervous system and may have a neuromodulatory role in endogenous pain relief pathways. However, recent results suggest that calcitonin is not present in the central nervous system and its analgesic effect is still controversial. For these reasons the antinociceptive effect of salmon calcitonin injected into the subarachnoid space of rats was examined. Intrathecal injection of calcitonin on the lumbar enlargement of rats caused a reversible increase of the hind paw lick latency in the hot plate test. No analgesia was observed with the vocalization test to eiectrical stimulation of the tail. In contrast, 10 pg morphine hydrochloride intrathecally caused analgesia in both tests. It is concluded that intrathecal calcitonin does not cause analgesia, but has a reversible blocking effect on motor responses.
SURGERY Diagnosis and management of genitofemoral neuralgia. - B.A. Harms, D.R. DeHaas, Jr. and J.R. Starling (Dept. of Surgery, University of Wisconsin Clinical Science Center, 600 Highland Ave., Madison, WI 53792, U.S.A.), Arch. Surg., 119 (1984) 339-341. The genitofemoral neuralgia syndrome consists of chronic pain and paresthesia in the distribution of the genitofemoral nerve. Genitofemoral nerve entrapment can occur after inguinal herniorrhaphy, appendectomy, biopsy and cesarean section. Failure to distinguish it from ilio-inguinal nerve entrapment can result in unnecessary inguinal reexploration, or in patients severely debilitated from chronic pain. Patients with persistent pain and paresthesia in the inguinal region following surgery should have a local il~o-inguinal nerve block. If this is unsuccessful in affecting relief of symptoms, a paravertebral block of Ll and L2 should be considered. Using these two blocks, a rational decision can then be made to operate on either the ilio-inguinal nerve or the genitofemoral nerve. Three cases of genitofemoral neuralgia treated by extraperitoneal excision of the genitofemoral nerve were reported. Peripheral nerve section as palliation for severe ischemic font pain. - M.Z. Papa, Y. Amsalem, A. Bass, A. Czerniak, M. Mozes and R. Adar (Dept. of General and Vascular Surgery and the Lubinski Vascular Institute, the Chaim Sheba Medical Center, Tel Hashomer, and Tel Aviv University Sackler Medical School, Israel) J. cardiovasc. Surg., 25 (1984) 115-117. Multisensory peripheral nerve divisions were performed in 17 elderly patients with severe ischemia, forefoot pain and non-healing lesions or localized gangrene. They were unsuitable for a vascular reconstructive operation, or for localized foot amputation. There were 4 females and 13 males with a mean age of 73. Ten were diabetic patients and thirteen had clinically significant coronary artery disease. All were faced with a major amputation. Considerable pain relief was achieved in all patients but only 5 patients retained a functional lower extremity for more than 6 months. Four of these 5 patients were non-diabetic. Peripheral nerve section is a useful procedure, but should be applied very selectively and only rarely in diabetic patients.
tests. - F.V. Abbott.
R.W. Grimes
and R. Melzack,
and
Brain Res.. 295 (1984)
77 - x4. Capsaicin is a neurotoxin that apparently produces a selective lesion of unmyelinated fibers which is associated with a loss of substance P in the skin nerves and dorsal horn of the spinal cord. This neural damage is also associated with decreased responsiveness to painful stimuli that varies with the route of administration of capsaicin and the age of the animal at the time of administratioll. ,4pplication of capsaicin to the sciatic nerve reduces responsiveness to pain in the foot-flick test which examines brief, threshold level pain. The purpose of the present study was to determine if a similar reduction occurs in the formalin test which examines suprathreshold, deep pain that persists for several hours. The sciatic nerve on one side in the rat was exposed and soaked for 15 min in a solution of capsaicin and the saphenous nerve was ligated and cut. The operated foot was tested for sensitivity to pain in the formalin and foot-flick tests 2 days to 12 weeks later both with and without morphine. The capsaicin treatment produced a substantial reduction in sensitivity to foot-flick heat pain at all times after surgery. In the formalin test, the effects were small and tended to suggest that the rats felt more rather than less pain. The capsaicin treatment markedly reduced the sensitivity of formalin test pain to morphine. This effect appeared about 1 week after surgery and persisted for 12 weeks. The results suggest that capsaicin-sensitjve uIl~nyelinated afferents play a role in the threshold level, non-damaging heat pain. but are not involved in pain resulting from tissue damage. However, these afferents appear to be important for the spinal action of morphine on this type of pain. Subarachnoid
injection of salmon calcitonin does not induce analgesia in rats. - Z.
Wiesenfeld-Hallin and A. Persson. Europ. J. Pharmacol., 104 (1984) 3755377. Calcitonin is a polypeptide produced in the thyroid gland of mammalian and non-mammalian species which causes hypocalcemia by inhibition of the release of calcium from bone. Clinically calcitonin is administered to treat Paget’s disease where bone turnover is enhanced. It has been proposed that calcitonin occurs in the
209
central nervous system and may have a neuromodulatory role in endogenous pain relief pathways. However, recent results suggest that calcitonin is not present in the central nervous system and its analgesic effect is still controversial. For these reasons the antinociceptive effect of salmon calcitonin injected into the subarachnoid space of rats was examined. Intrathecal injection of calcitonin on the lumbar enlargement of rats caused a reversible increase of the hind paw lick latency in the hot plate test. No analgesia was observed with the vocalization test to eiectrical stimulation of the tail. In contrast, 10 pg morphine hydrochloride intrathecally caused analgesia in both tests. It is concluded that intrathecal calcitonin does not cause analgesia, but has a reversible blocking effect on motor responses.
SURGERY Diagnosis and management of genitofemoral neuralgia. - B.A. Harms, D.R. DeHaas, Jr. and J.R. Starling (Dept. of Surgery, University of Wisconsin Clinical Science Center, 600 Highland Ave., Madison, WI 53792, U.S.A.), Arch. Surg., 119 (1984) 339-341. The genitofemoral neuralgia syndrome consists of chronic pain and paresthesia in the distribution of the genitofemoral nerve. Genitofemoral nerve entrapment can occur after inguinal herniorrhaphy, appendectomy, biopsy and cesarean section. Failure to distinguish it from ilio-inguinal nerve entrapment can result in unnecessary inguinal reexploration, or in patients severely debilitated from chronic pain. Patients with persistent pain and paresthesia in the inguinal region following surgery should have a local il~o-inguinal nerve block. If this is unsuccessful in affecting relief of symptoms, a paravertebral block of Ll and L2 should be considered. Using these two blocks, a rational decision can then be made to operate on either the ilio-inguinal nerve or the genitofemoral nerve. Three cases of genitofemoral neuralgia treated by extraperitoneal excision of the genitofemoral nerve were reported. Peripheral nerve section as palliation for severe ischemic font pain. - M.Z. Papa, Y. Amsalem, A. Bass, A. Czerniak, M. Mozes and R. Adar (Dept. of General and Vascular Surgery and the Lubinski Vascular Institute, the Chaim Sheba Medical Center, Tel Hashomer, and Tel Aviv University Sackler Medical School, Israel) J. cardiovasc. Surg., 25 (1984) 115-117. Multisensory peripheral nerve divisions were performed in 17 elderly patients with severe ischemia, forefoot pain and non-healing lesions or localized gangrene. They were unsuitable for a vascular reconstructive operation, or for localized foot amputation. There were 4 females and 13 males with a mean age of 73. Ten were diabetic patients and thirteen had clinically significant coronary artery disease. All were faced with a major amputation. Considerable pain relief was achieved in all patients but only 5 patients retained a functional lower extremity for more than 6 months. Four of these 5 patients were non-diabetic. Peripheral nerve section is a useful procedure, but should be applied very selectively and only rarely in diabetic patients.