Potential strategies against age-related brain deterioration. Dietary and pharmacological approaches

Nicotine enhances stimulus detection performance of middle- and old-aged rats: a longitudinal study

The effects of nicotine on sustained attention were tested in F344xBN male rats when they were chronologically middle and old aged. The rats (n = 11) were trained in a two-choice, stimulus detection task in which a press of one of two levers was reinforced with food, with the correct lever indicated by the position of a briefly illuminated light. They were tested when they were 24-25 and 34-35 months of age (i.e., at 60-68% and 85-95%, respectively of their expected median life span) after saline or 0.1-0.5 mg/kg doses of nicotine (SC). A significant dose-related improvement in percent correct choices and decrease in choice response times was found at both ages, and there was no significant main effect of age or an age by dose interaction. These results support the position that nicotine can enhance attentional processes in rats throughout their life span. Nicotine and other nicotinic agonists may have efficacy in the treatment of disorders such as Alzheimer's disease.

Caloric restriction enhances evoked DA overflow in striatum and nucleus accumbens of aged Fischer 344 rats

Previous studies have shown deficits in DA neuronal systems in senescence. Other studies indicate that prolonged dietary restriction can attenuate many of the detrimental effects of age. We have shown previously using in vivo electrochemistry that K+-evoked striatal DA overflow decreases as a function of age. This was a regional effect that appeared to be due to functional changes in DA neurons, rather than a decrease in the storage and synthesis of DA. In the present studies, we used in vivo electrochemistry to investigate the effects of caloric restriction on age related decreases in K+-evoked DA overflow along a dorsal to ventral axis in the striatum of aged female Fischer 344 rats. Aged (26-28-month-old) diet restricted animals (DRF) showed evoked DA overflow that was significantly greater in amplitude and duration compared to aged (26-28-month-old) ad lib fed animals (ALF). These results provide additional evidence that decreased DA neuronal function resulting from age is improved by caloric restriction.