Biomedical subjects
Michelle Turner
Publications and source records attributed to Michelle Turner.
Cannabinoids attenuate capsaicin-evoked hyperalgesia through spinal and peripheral mechanisms.
Previous studies in our laboratory have demonstrated that cannabinoids administered intravenously attenuate the duration of nocifensive behavior and block the development of hyperalgesia produced by intraplantar injection of capsaicin. In the present study, we extended these observations and determined whether cannabinoids attenuate capsaicin-evoked pain and hyperalgesia through spinal and peripheral mechanisms, and whether the antihyperalgesia was receptor mediated. Separate groups of rats were pretreated 7 min before capsaicin with an intrathecal injection of vehicle or the cannabinoid receptor agonist WIN 55,212-2 at doses of 0.1, 1.0 or 10 microg in 10 microl. Although the intrathecal application of WIN 55,212-2 did not alter nocifensive behavior following capsaicin, it produced a dose-dependent decrease in hyperalgesia to heat and mechanical stimuli. Intrathecal pretreatment with the CB1 receptor antagonist SR141716A (10 microg) blocked the antihyperalgesia produced by WIN 55,212-2. The ability of intrathecal administration of WIN 55,212-2 to attenuate hyperalgesia was not due to motor deficits since the highest dose of WIN 55,212-2 did not alter performance on the rota-rod test. To investigate whether cannabinoids attenuated capsaicin-evoked hyperalgesia through peripheral mechanisms, separate groups of rats were pretreated with an intraplantar injection of WIN 55,212-2 at doses of 0.1, 1.0, 10 or 30 microg in 100 microl 5 min before capsaicin. Intraplantar pretreatment with WIN 55,212-2 produced a dose-dependent attenuation of hyperalgesia to heat, but did not attenuate mechanical hyperalgesia or the duration of nocifensive behavior. The inactive enantiomer WIN 55,212-3 did not alter the development of hyperalgesia. SR141716A (100 microg) co-injected with WIN 55,212-2 (30 microg) partially attenuated the effects of WIN 55,212-2 on hyperalgesia to heat. Intraplantar injection of the highest dose of WIN 55,212-2 did not interfere with the development of hyperalgesia following capsaicin injection into the contralateral paw. These data show that cannabinoids possess antihyperalgesic properties at doses that alone do not produce antinociception, and are capable of acting at both spinal and peripheral sites.
Physical inactivity and socioeconomic status in Canadian adolescents.
UNLABELLED: Physical activity is an important determinant of population health. In this paper, we examine levels of physical activity among Canadian adolescents in relation to socioeconomic status. METHODS: Data from the Canadian Community Health Survey, Cycle 2.1, conducted in 2003, were used to evaluate the association between socioeconomic status and physical activity. This survey included 9,294 males between 12 and 20 years of age, and 9,147 females in the same age range. RESULTS: Among adolescents aged 12 to 20 years, 55.9% of males and 39.2% of females were physically active. The proportion of subjects in the active category tended to decrease with age in both males and females. Adolescents from low income families were more physically inactive (odds ratio=1.30, 95% confidence interval=1.29-1.32) than those from high income families. CONCLUSION: Physical inactivity in adolescence represents an important population health issue in Canada. Physical activity levels tended to be higher among males, younger people, and those with higher socioeconomic status. Multi-sectoral policies and initiatives are needed to create environments that promote physical activity among Canadian youth.