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J H Rosland

Publications and source records attributed to J H Rosland.

14 recordsLinked to original sources
PubMed1992

Acute and long term effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in tests of nociception in mice.

Acute and long term changes in nociception after administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) 80 mg/kg (four injections of 20 mg/kg given at two hr intervals) were investigated in mice. MPTP caused shivering, lacrimation, salivation, teeth chattering and fur erection a few minutes after drug injection, but all these behavioural changes were normalized within 30 min., when the first behavioural testing was performed. No significant alteration in general behaviour, sensorimotor performance or body temperature could be detected at the time of nociceptive testing. The acute effects of MPTP on nociception were a reduced response latency in the tail flick test and a prolonged response latency compared to controls in the constant temperature hot plate test. No significant effects of MPTP were found in the increasing temperature hot plate test. The long term effects were a reduced response latency both in the tail flick test and the constant temperature hot plate test, indicating that the MPTP induced lesions of dopaminergic pathways result in hyperalgesia. In the increasing temperature hot plate test and the formalin test, no significant long term changes were demonstrated. Seven days after injection, the dopamine content was reduced to 62% of control values in striatum, to 51% in the rest of the forebrain, and to 41% in the spinal cord. Noradrenaline levels were only slightly and transiently reduced. Serotonin levels were not affected 7 days after injection, but 14 days after injection, a great increase was found in the forebrain and in the spinal cord. The results suggest that dopaminergic systems tonically inhibit nociception.(ABSTRACT TRUNCATED AT 250 WORDS)

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1991

The increasing-temperature hot-plate test: an improved test of nociception in mice and rats.

The increasing-temperature hot-plate test has several advantages compared to the conventional hot-plate test, but available equipment has been impractical and restricted with regard to stimulus control. We now describe an apparatus consisting of an aluminum plate that is heated and cooled by Peltier elements in contact with its lower surface. Several plates can be used simultaneously, individually controlled by electronic proportional feedback circuits. The set temperature of the feedback circuit is controlled by a computer program run on an IBM XT-compatible PC, so that a linear increase in temperature is achieved. Experiments were performed using rats and mice, with hindpaw licking as an end-point criterion. Experiments with various heating rates showed that 3.0 degrees C/min is the lowest rate that can be applied without signs of stress in the animals. On the basis of the recorded data, nociceptive temperature thresholds were calculated to be approximately 44.5 degrees C for both rats and mice. Inspection of the paws after analgesic treatment and exposure to different end-point temperatures suggested that a cutoff temperature of 50 degrees C should be employed to minimize tissue damage. Testing at ambient temperatures of 18 degrees and 28 degrees C yielded similar results for rats, whereas mice responded at significantly higher plate temperatures in the colder environment. Dose-related antinociceptive effects were demonstrated for morphine and paracetamol in both species. The results confirm that the increasing-temperature hot-plate test is a valuable test of nociception, which is also suitable for demonstrating the antinociceptive effects of nonopioid analgesics. The test may also be used to estimate the nociceptive temperature threshold.

Acetaminophen↗
PubMed1990

Benzodiazepine-induced antagonism of opioid antinociception may be abolished by spinalization or blockade of the benzodiazepine receptor.

The mechanisms underlying benzodiazepine antagonism of opioid antinociception were studied using the tail flick test and the hot plate test in mice. Both single-dose and repeated diazepam treatment antagonized the antinociceptive effect of morphine. The specific benzodiazepine antagonist flumazenil completely reversed the antagonism between diazepam and morphine. Mid-thoracic spinalization also abolished the antagonism, indicating that the antagonism takes place at higher levels in the CNS. Neither diazepam nor midazolam showed any affinity for opioid mu or kappa receptors in membranes prepared from mouse forebrain. Taken together with the results of other studies of interactions between GABAergic drugs and opioids, the results indicate that a benzodiazepine receptor-mediated mechanism at higher levels in the CNS, possibly in the brainstem, blocks the effect of opioids on nociceptive transmission.

Analgesics↗
PubMed1990

Diazepam attenuates morphine antinociception test-dependently in mice.

The influence of diazepam on the antinociceptive effect of morphine was studied using four different nociceptive tests in mice. In the tail flick test, diazepam induced a dose-dependent reduction of the morphine effect, with an almost total reversed morphine effect following diazepam 2 mg/kg. The effect could not be explained by altered tail skin temperature or pharmacokinetic changes. Diazepam 1 mg/kg and higher induced sedation and significantly impaired the performance in a rotarod test, a dose of 0.5 mg/kg diazepam was therefore used in the other nociceptive tests. This dose of diazepam significantly attenuated the antinociceptive effect of morphine in the constant temperature hot plate test and the tail flick test. In the increasing temperature hot plate test and in the formalin test, no effect of diazepam on the nociceptive effect of morphine was observed. The results indicate that diazepam antagonizes the effect of morphine dependent upon the test employed. No antagonism could be observed in tests with a long-lasting stimulus, and a response integration probably at a rather high level in the CNS. In the two tests showing antagonism, the stimulus is more short-lasting, and at least for the tail flick test, the integration takes place at a lower level in the CNS.

Analgesics↗
PubMed1990

The effect of nefopam and its enantiomers on the uptake of 5-hydroxytryptamine, noradrenaline and dopamine in crude rat brain synaptosomal preparations.

The effect of (+/-), (+) and (-)-nefopam on the uptake of 5-hydroxytryptamine (5-HT), noradrenaline and dopamine in synaptosomal preparations from rat forebrain, hippocampus and striatum has been investigated. All three forms of nefopam inhibited the amine uptake in the investigated structures, the order of potency being (+) greater than (+/-) greater than (-). (+)-Nefopam was 7-30 times more potent than (-)-nefopam. The same order of potency has also been found for the antinociceptive effect of these three forms, however, the differences were smaller. Inhibition of 5-HT and noradrenaline uptake may not be the sole mechanism underlying the analgesic effect of nefopam.

Animals↗
PubMed1990

1,4-Benzodiazepines antagonize opiate-induced antinociception in mice.

The influence of diazepam, midazolam, and flunitrazepam on the antinociceptive effect of morphine, fentanyl, and buprenorphine was studied using the hot-plate test and the tail-flick test in mice. Diazepam and midazolam induced a dose-dependent attenuation of the effect of all three opiates in both tests of nociception. Flunitrazepam antagonized the antinociceptive effect only in the tail-flick test. The benzodiazepine effect could not be explained by altered tail-skin temperature. The antagonism did not correlate well with the sedative or muscle-relaxing properties of the benzodiazepines, and a different mechanism may therefore be involved. It is proposed that the antagonism represents an interaction between benzodiazepines and opioid systems in the brain participating in modulation of nociceptive inputs.

Analgesia↗
PubMed1989

Mechanisms of orphenadrine-induced antinociception in mice: a role for serotonergic pathways.

The possible involvement of central serotonergic pathways in the mechanism of action of orphenadrine citrate was investigated in male albino mice. Orphenadrine (20 mg/kg) did not alter the concentration of 5-hydroxytryptamine (5-HT) or its metabolite 5-hydroxyindole acetic acid in the frontal cortex or spinal cord, nor did it, in moderate concentrations, inhibit the uptake of [14C]5-HT, [3H]noradrenaline ([3H]NA) or [3H]dopamine ([3H]DA) into crude synaptosomal preparations from the cortex. The antinociceptive effect of orphenadrine was studied in the formalin test and in the increasing temperature hot plate test. No sensorimotor impairment was observed for doses of 30 mg/kg or lower. A general depletion of serotonin by means of p-chlorophenylalanine significantly reduced the effect of orphenadrine in both tests, while lesion of the ascending serotonergic systems by means of p-chloroamphetamine did not affect the analgesia. It is concluded that the antinociceptive effect of orphenadrine may be mediated in part via the raphe-spinal serotonergic systems.

Analgesics↗
PubMed1989

Both single-dose and repeated administration of clomipramine reduces the behavioural response to intrathecal capsaicin in mice.

Capsaicin injected intrathecally releases substance P from primary sensory nerve endings, and induces a pain related behaviour in mice consisting of licking, biting and scratching directed to the distal part of the body. This behavioural response was reduced by approximately 35% after intraperitoneal administration of clomipramine, 10 mg/kg, 1 hr in advance, and by 38% after repeated administration (10 mg/kg/day for 9 days). Twenty-four hr after the last repeated clomipramine injection, the response after capsaicin was still reduced by 36%, indicating a long-lasting effect of repeated treatment. The results indicate that clomipramine has analgesic properties against pain of central origin both after single-dose and repeated administration.

Animals↗
PubMed1989

The role of tail skin temperature in the facilitation of the tail-flick reflex after spinal transection or interference with descending serotonergic neurotransmission.

We examined in mice whether tail skin temperatures and tail-flick reflexes were changed after spinal transection or intrathecal (i.th.) injection of the serotonin (5-HT) neurotoxin 5,6-dihydroxytryptamine (5,6-DHT) or the 5-HT receptor antagonist metergoline. Transection of the spinal cord reduced tail-flick latency (the time needed to evoke the tail-flick reflex by radiant heat) and increased tail skin temperature 15-21 days after surgery. Analysis of covariance showed that the effect of tail skin temperature on tail-flick latency was far more pronounced than the effect of spinal transection. Intrathecal injection of 5,6-DHT (5 or 10 micrograms mouse-1), which extensively reduced the spinal levels of 5-HT, reduced tail-flick latency and increased tail skin temperature 1-5 days after treatment. Similarly, tail-flick latency was shortened and tail skin temperature elevated 15 min after i.th. injection of metergoline (0.5 micrograms mouse-1). Analysis of covariance showed no significant effect of i.th. 5,6-DHT or i.th. metergoline on tail-flick latency. Tail skin temperature, on the other hand, had a highly significant effect on tail-flick latency. The results show that the facilitation of the tail-flick reflex in spinally transected mice and mice injected i.th. with 5,6-DHT or metergoline is mainly caused by increased tail skin temperature. The data do not indicate that descending 5-HT pathways tonically inhibit the tail-flick reflex.

5,6-Dihydroxytryptamine↗
PubMed1988

Pharmacological manipulation with the descending serotonergic system or transection of the mouse spinal cord has no effect on ependymal ultrastructure.

In order to investigate an effect of descending nerve fibres on mouse spinal cord ependymal ultrastructure, pharmacological manipulation with the serotonergic system or transection of the spinal cord was done. Biochemical analysis showed an 83% reduction of serotonin content in spinal cord tissue after p-chlorophenylalanine injections and a 93% reduction after transection. However, none of the experimental animals showed changes in ependymal ultrastructure compared to control animals as revealed by electron microscopy.

Animals↗
PubMed1987

The effect of diazepam on nociception in mice.

The antinociceptive properties of diazepam were evaluated in mice, using four different pain tests and different doses of the drug (0.2, 0.5, 1.0 and 2.0 mg/kg). In the tail flick test and the increasing temperature hot plate test there were no effects. In the formalin test reduced licking was observed for the highest dose of diazepam. However, this dose also induced clear sedation possibly causing the reduced licking response. In the constant temperature hot plate test a hyperalgesia was found for all doses tested. This hyperalgesia was not observed in animals adapted to the test apparatus, suggesting that the "hyperalgesic" effect of diazepam may be due to reduced stress analgesia. The serum concentrations of the drug were comparable to therapeutic levels in humans. It was concluded that the sedative and anxiolytic effects of diazepam may influence the results of nociceptive tests, but the drug has probably no effect on nociception in itself.

Analgesics↗