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“Nicotine prominently mediates the behavioral effects
of tobacco consumption, either through smoking or when taking tobacco by snuff or chew. However, many studies question the exclusive role of nicotine in these effects. The use of preparations containing all the components of tobacco, such as tobacco and smoke extracts, may be more suitable than nicotine alone to investigate the behavioral effects of smoking and tobacco intake. In the present study, the electrophysiological effects of tobacco and smoke on ventral tegmental area dopaminergic (DA) neurons were examined selleck chemicals llc in vivo in anesthetized wild-type (WT), beta 2-nicotinic acetylcholine receptor (nAChR) knockout (beta 2-/-), alpha 4-/-, and alpha 6-/- mice and compared with those of nicotine alone. In WT mice, smoke and nicotine had similar potentiating effects on DA cell activity, but
the action www.selleckchem.com/products/sbe-b-cd.html of tobacco on neuronal firing was weak and often inhibitory. In particular, nicotine triggered strong bursting activity, whereas no bursting activity was observed after tobacco extract (ToE) administration. In beta 2-/- mice, nicotine or extract elicited no modification of the firing patterns of DA cells, indicating that extract acts predominantly through nAChRs. The differences between DA cell activation profiles induced by tobacco and nicotine alone observed in WT persisted in alpha 6-/- mice but not in alpha 4-/- mice. These results would suggest that tobacco has lower addiction-generating properties compared with either nicotine alone or smoke. The weak activation and prominent inhibition obtained with ToEs suggest that tobacco contains compounds that counteract PIK-5 some of the activating effects of nicotine and promote inhibition on DA cell acting through
alpha 4 beta 2*-nAChRs. The nature of these compounds remains to be elucidated. It nevertheless confirms that nicotine is the main substance involved in the tobacco addiction-related activation of mesolimbic DA neurons. Neuropsychopharmacology (2011) 36, 2244-2257; doi: 10.1038/npp.2011.112; published online 29 June 2011″
“The purpose of this study was to investigate age-related differences in cutaneous temperature thresholds for warm thermal sensitivity in a thermoneutral (28 degrees C) and in a cool environment (22 degrees C). Peripheral warm thresholds were measured on nine body regions (cheek, chest, abdomen, upper arm, forearm, hand, thigh, shin, and foot) using a thermal stimulator in 12 young (22 +/- 1 years) and 13 elderly male subjects (67 +/- 3 years). The results showed that: (1) mean skin temperature did not differ by age in both environments; (2) the cutaneous warm thresholds for the hand, shin, and foot were significantly higher for the elderly than for the young in both environments (p < 0.