The effects of single intravenous doses of naloxone (0.8 and 1.6 mg) in a variety of performance ... more The effects of single intravenous doses of naloxone (0.8 and 1.6 mg) in a variety of performance tasks and on subjective ratings of mood and bodily symptoms were investigated in 12 student volunteers. Naloxone was without effect on any of the performance measures. However, 5 min after naloxone (1.6 mg) the subjects felt significantly more troubled, mentally slow, incompetent, withdrawn and physically tired, and less irritable. These effects appeared to be dose-related since 0.8 mg produced similar, but not statistically significant changes. Sixty-five minutes after the higher dose subjects felt significantly more muzzy and incompetent; in contrast to the effects at 5 min they now felt significantly more irritable. These results are difficult to explain solely in terms of opiate receptor blockade.
Rats exposed to a cloth impregnated with the odor of a cat made fewer contacts with the cloth and... more Rats exposed to a cloth impregnated with the odor of a cat made fewer contacts with the cloth and spent more time sheltering under the food and water hopper than did rats exposed to a neutral odor. In two experiments there was little evidence of between-trial habituation of these responses to cat odor. The pattern of within-session changes depended on the trial duration (15 or 60 min) and the initial level of the avoidance responses. In order to test for conditioned generalization of the avoidance responses to the test situation, rats with two previous exposures to cat odor were given a third trial in which they were exposed to a neural odor. Experiment 1 showed that those previously exposed to cat odor for two 15 min trials spent more time sheltering when exposed to the neutral odor cloth than those previously exposed to the neutral odor. Experiment 2 confirmed this effect and found that the increase in sheltering was even more marked for a group exposed to cat odor for 60 min on trial 1. The number of contacts with the neutral odor cloth on trial 3 was reduced only in the group of high avoiders (defined as making no contacts with the cat odor cloth in the first 5 min of trial 1). Thus, both the duration of exposure to cat odor and the initial response level were important in determining the conditioned generalization of the responses to a phobic stimulus.
Huntington's disease transgenic mice were tested in the elevated plus-maze test of anxiet... more Huntington's disease transgenic mice were tested in the elevated plus-maze test of anxiety at 6, 8, 10 and 12 weeks of age. At all ages, they showed significant and striking increases in the percentages of open arm entries and time spent on the open arms, compared with their normal littermates, indicating reduced anxiety. These increases were not secondary to a non-specific stimulant effect, since the transgenic mice made fewer closed arm entries, significantly so from 10 weeks of age. The mice were also tested in the holeboard, which provides measures of locomotor activity and directed exploration. From 8 weeks of age, the Huntington's mice were significantly less active than their normal littermates and made fewer exploratory head-dips. The increased open arm activity in the elevated plus-maze cannot therefore be secondary to increased exploration in the transgenic mice. In order to determine whether the reduced anxiety was due to differences in benzodiazepine receptor function, the mice were challenged with the benzodiazepine receptor antagonist, flumazenil. The results indicated that some of the reduced anxiety could be attributed to the presence of an endogenous anxiolytic ligand.
When reviewing the consequences of zinc deficiency in humans, Hambidge (1981) commented behaviour... more When reviewing the consequences of zinc deficiency in humans, Hambidge (1981) commented behavioural abnormalities are prominent in severe zinc deficiency (Walravens et al. 1978) and may also occur in less severe cases of zinc depletion. Irritability, lethargy and depression are evident even at an early stage in the clinical course. Improvement in hedonic tone and motivation to engage in the environment follow rapidly after the institution of zinc therapy.
The effects of single intravenous doses of naloxone (0.8 and 1.6 mg) in a variety of performance ... more The effects of single intravenous doses of naloxone (0.8 and 1.6 mg) in a variety of performance tasks and on subjective ratings of mood and bodily symptoms were investigated in 12 student volunteers. Naloxone was without effect on any of the performance measures. However, 5 min after naloxone (1.6 mg) the subjects felt significantly more troubled, mentally slow, incompetent, withdrawn and physically tired, and less irritable. These effects appeared to be dose-related since 0.8 mg produced similar, but not statistically significant changes. Sixty-five minutes after the higher dose subjects felt significantly more muzzy and incompetent; in contrast to the effects at 5 min they now felt significantly more irritable. These results are difficult to explain solely in terms of opiate receptor blockade.
Rats exposed to a cloth impregnated with the odor of a cat made fewer contacts with the cloth and... more Rats exposed to a cloth impregnated with the odor of a cat made fewer contacts with the cloth and spent more time sheltering under the food and water hopper than did rats exposed to a neutral odor. In two experiments there was little evidence of between-trial habituation of these responses to cat odor. The pattern of within-session changes depended on the trial duration (15 or 60 min) and the initial level of the avoidance responses. In order to test for conditioned generalization of the avoidance responses to the test situation, rats with two previous exposures to cat odor were given a third trial in which they were exposed to a neural odor. Experiment 1 showed that those previously exposed to cat odor for two 15 min trials spent more time sheltering when exposed to the neutral odor cloth than those previously exposed to the neutral odor. Experiment 2 confirmed this effect and found that the increase in sheltering was even more marked for a group exposed to cat odor for 60 min on trial 1. The number of contacts with the neutral odor cloth on trial 3 was reduced only in the group of high avoiders (defined as making no contacts with the cat odor cloth in the first 5 min of trial 1). Thus, both the duration of exposure to cat odor and the initial response level were important in determining the conditioned generalization of the responses to a phobic stimulus.
Huntington's disease transgenic mice were tested in the elevated plus-maze test of anxiet... more Huntington's disease transgenic mice were tested in the elevated plus-maze test of anxiety at 6, 8, 10 and 12 weeks of age. At all ages, they showed significant and striking increases in the percentages of open arm entries and time spent on the open arms, compared with their normal littermates, indicating reduced anxiety. These increases were not secondary to a non-specific stimulant effect, since the transgenic mice made fewer closed arm entries, significantly so from 10 weeks of age. The mice were also tested in the holeboard, which provides measures of locomotor activity and directed exploration. From 8 weeks of age, the Huntington's mice were significantly less active than their normal littermates and made fewer exploratory head-dips. The increased open arm activity in the elevated plus-maze cannot therefore be secondary to increased exploration in the transgenic mice. In order to determine whether the reduced anxiety was due to differences in benzodiazepine receptor function, the mice were challenged with the benzodiazepine receptor antagonist, flumazenil. The results indicated that some of the reduced anxiety could be attributed to the presence of an endogenous anxiolytic ligand.
When reviewing the consequences of zinc deficiency in humans, Hambidge (1981) commented behaviour... more When reviewing the consequences of zinc deficiency in humans, Hambidge (1981) commented behavioural abnormalities are prominent in severe zinc deficiency (Walravens et al. 1978) and may also occur in less severe cases of zinc depletion. Irritability, lethargy and depression are evident even at an early stage in the clinical course. Improvement in hedonic tone and motivation to engage in the environment follow rapidly after the institution of zinc therapy.
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