Characterization of a dose-response curve for nicotine-induced conditioned taste aversion in rats: relationship to elevation of plasma beta-endorphin concentration

In the first experiment a conditioned taste aversion paradigm was used to characterize a dose-response curve for the aversive properties of nicotine in male Sprague-Dawley rats. Doses of nicotine ranging from 0.01 to 0.46 mg/kg, 2.0 ml of 0.47 M lithium chloride, or saline were injected, ip, 10 min after exposure to a novel saccharin solution. Amount of saccharin consumed in a two-bottle test was assessed 72 h later. Nicotine doses of 0.046 mg/kg and above produced a significant degree of conditioned taste aversion. In a second experiment, four groups of 10 rats each were injected with saline, 0.022 mg/kg nicotine, 0.46 mg/kg nicotine, or 2.0 ml 0.47 of M LiCl. Doses of 0.46 mg/kg nicotine and 0.47 M LiCl elevated plasma beta-endorphin concentrations significantly above saline control values. The 0.022 mg/kg dose, the highest dose that did not produce conditioned taste aversion in Experiment 1, did not significantly increase plasma beta-endorphin concentrations. This finding suggests that doses of nicotine that produce conditioned taste aversion also promote the release of pituitary stress hormones. Taken together these data suggest that some of the pharmacological and behavioral effects attributed to nicotine, including the release of endogenous neuromodulators, may be dose-dependent concomitants of the aversive effects of nicotine in nicotine-naive animals.     

Decision-making processes of youth

Research supports the theory that after administrators make a decision, feedback, both positive and negative, and also the administrators' perceived security vis-à-vis their position affect their level of commitment to a course of action. However, this research fails to recognize that subjects of college age playing administrators in the simulated, experimental treatments which have been presented in the research had nothing personally to lose if they made a bad decision--an orientation contradictory to the reality of most actual administrative positions. Additionally, the research ignores the interactional effects of the personality of decision makers in terms of their anxiety levels and the judgments they make. This study took both of these considerations into account by creating a decision-making situation within which prospective administrators made monetary commitments to long-term goals while their anxiety level, both as a basic personality attribute and an index of the reality of the decision-making process, was monitored under conditions of varying levels of job insecurity and resistance to their policies in relation to their decisions. Analyses revealed that contrary to the results of past research which used college students as subjects: (1) there is a significant negative correlation between levels of anxiety and commitments to previously chosen courses of action; (2) there are no significant effects of job security on commitment; and, most importantly, (3) high resistance to a policy decision leads to significantly less monetary commitments to long-term goals. The findings suggest that the basis for the contradictory results lies with the anxiety level of decision makers and the realism of experiencing a loss by making poor decisions.     

The prolonged effects of naloxone on play behavior and feeding in the rat

The effects of naloxone on social play and feeding behaviors of postweanling and adult Long-Evans hooded rats were studied. Administration of 1.0, 5.0, or 10.0 mg/kg naloxone reduced play in a dose-related fashion. The effects of a 5.0-mg/kg dose of naloxone could be detected at least 3 h after administration, in terms of both a decrease in social behavior and decreased food consumption, indicating that the behavioral time course of naloxone effects is greater than some reports in the pharmacokinetic literature suggest.     

Speed of information processing in academically gifted youths

A group of bright-average 7th grade junior-high-school students was contrasted with a group of manifestly academically gifted students of comparable age who were taking college-level courses in mathematics and science. The groups differed significantly and markedly (showing an overall mean difference of 1.34 SD) on every one of the nine different reaction-time (RT) tasks measuring the speed with which persons perform various elementary cognitive processes. The results indicate that: (1) various RT measurements discriminate about as much between intellectually average and superior groups as past studies have found RT measurements to discriminate between average and subnormal groups: and (2) the academically gifted differ from their nongifted age-peers in more than just scholastic knowledge and advanced problem-solving skills—they differ fundamentally in speed of information processing on extremely simple cognitive tasks with average response latencies of between 0.3 and 1.5 sec.