Biomedical subjects
S J Kitchener
Publications and source records attributed to S J Kitchener.
An examination of the behavioural specificity of hypophagia induced by 5-HT1B, 5-HT1C and 5-HT2 receptor agonists using the post-prandial satiety sequence in rats.
Previous studies have shown that administration of 5-HT1B, 5-HT1C or 5-HT2 agonists decreases food intake in rats. However, it has not been established whether these drugs induce satiety or decrease feeding by a non-specific mechanism. In the present study the post-prandial satiety sequence was used to characterise the actions of the 5-HT2 receptor agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), the 5-HT1B/5-HT1C receptor agonists, 1-(3-chorophenyl) piperazine (mCPP) and 1-[3-(trifluoromethyl)phenyl] piperazine (TFMPP), and the 5-HT1B agonist, 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)H-indole (RU 24969), on feeding in rats. All four compounds reduced food intake in rats that had been food deprived overnight. The 5-HT1B/5-HT1C agonists, TFMPP (at a dose of 1.0 mg/kg) and mCPP (at a dose of 3.0 mg/kg), appeared to produce satiety as their effects on the satiety sequence were similar to those induced by a food pre-load. In contrast, the 5-HT1B agonist RU 24969 and the 5-HT2 agonist DOI did not produce behavioural profiles that resembled satiety. Thus, RU 24969 elevated active behaviours and did not accelerate resting whereas DOI appeared to induce hypophagia by a non-specific fragmentation of behaviour. The results suggest that simultaneous activation of 5-HT1B and 5-HT1C receptors may be sufficient to elicit behaviourally specific satiety in the rat. In contrast, selective activation of 5-HT2 receptors does not induce satiety but elicits active behaviours and decreases feeding by response competition.
The selective CCK-B receptor antagonist L-365,260 enhances morphine analgesia and prevents morphine tolerance in the rat.
The effects of the selective CCK-A antagonist L-365,031 and the selective CCK-B antagonist L-365,260 on morphine analgesia and opiate tolerance and dependence in rats were examined. L-365,031 and L-365,260 had no effect on baseline pain thresholds in the radiant heat tail flick test but enhanced analgesia induced by a submaximal dose of morphine (4 mg/kg). Similarly, L-365,260 did not effect pain thresholds in the paw pressure test but enhanced morphine analgesia in this model. Rats injected twice daily for 6 days with incremental doses of morphine became tolerant to the analgesic effects of the drug. Twice daily injections of either 8 mg/kg L-365,031 or 0.2 mg/kg L-365,260 prevented the development of tolerance to morphine analgesia. In contrast, L-365,260 had no influence on the development of opiate dependence in these animals, as assessed by naloxone-precipitated withdrawal. The results of the present study, when considered together with previous data, indicate that the rank order of potency of non-peptide CCK antagonists for enhancing morphine analgesia is L-365,260 greater than MK-329 greater than L-365,031. This rank order correlates well with the potency of the antagonists in blocking CCK-B receptors in rodents and suggests that CCK/opiate interactions in this species are mediated by CCK-B receptors.
Malaria in the Australian Defence Force during and after participation in the International Force in East Timor (INTERFET).
Malaria in Australian Defence Force members has been far more common in East Timor than in other recent overseas deployments. By six months after all 5,500 members of the International Force in East Timor had returned to Australia, 267 malaria infections had been reported to the Army Malaria Institute. Only 64 of those affected had their first clinical episode during their 4-5 months in East Timor, and about two-thirds of these infections were caused by Plasmodium falciparum. The remaining 212 soldiers developed their first symptoms after returning to Australia, and all but two infections were caused by P. vivax. After treatment, 44 soldiers had relapses of their vivax infections; 11 had a second relapse and two had a third relapse. These findings raise several issues about prevention and management of malaria in the ADF.