RESUMEN
Two experiments examined the effects of age, genetic strain, and nicotine on acoustic startle response (ASR) amplitude and prepulse inhibition (PPI) in rats. ASR amplitude measures reactivity to external stimulation, and PPI is used as an index of sensory gating related to attention. Both ASR amplitude and PPI have been previously reported to be increased by nicotine in adult rats. Experiment 1 examined effects of chronically administered nicotine and saline on ASR and PPI in Wistar, Long-Evans, and Sprague-Dawley rats (40 days of age). Experiment 2 examined the effects of chronically administered nicotine and saline in Sprague-Dawley rats of two age groups: 40 and 70 days of age at the beginning of the study. ASR amplitude differed significantly across strains with the values for Wistar > Sprague-Dawley > Long-Evans, and there were no differences in percent of PPI among the three strains. In addition, results of Experiment 2 indicated that older rats had significantly greater ASR amplitudes and PPI than younger rats. Consistent with previous reports, nicotine increased ASR and PPI in the older rats; however, there were no significant differences in the younger rats. Therefore, age and genetic strain are important variables in the analysis of nicotine's effects on startle behaviors in rats.
Asunto(s)
Envejecimiento/psicología , Nicotina/farmacología , Reflejo de Sobresalto/efectos de los fármacos , Animales , Masculino , Ratas , Ratas Sprague-Dawley , Ratas Wistar , Especificidad de la EspecieRESUMEN
There is an inverse relationship between nicotine and body weight. It has been proposed that this inverse relationship is partially mediated by insulinergic actions, but the effect of nicotine on insulin only has been reported for male rats. The present experiment was designed to examine the effect of nicotine administration on body weight and plasma insulin in female and male rats. In addition, the effects of anesthesia prior to sacrifice on plasma insulin were examined. Nicotine reduced body weight and plasma insulin in female and male rats. In addition, the use of an anesthetic prior to sacrifice was associated with higher plasma insulin levels for male rats. These findings are consistent with the interpretation that insulinergic mechanisms play a role in the nicotine-body weight relationship.