• Korean Journal of Biological Psychiatry
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• v.5 no.1
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• pp.83-94
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• 1998

Objectives : Phencyclidine(PCP) or PCP-like substances such as ketamine have been known to rekindle the cognitive dysfunction in schizophrenia. The aims of this study were to identify whether PCP-like substances can produce cognitive deficit in schizophrenia, to discuss relation with aging process, and finally to speculate underlying neurochemical mecha-nisms by various drug responses. Methods : In experiment I, radial maze tests were done in 24 Sprague-Dawley rats for 3 days to get baseline data. Being divided into 4 groups(6 rats respectively) of normal aged, normal adult controls, atropine-treated and ketamine-treated, the radial maze tests were repeated on every week for 6 weeks, and then the rats were sacrificed by intracardiac perfusion with phosphate-buffered 10% formaldehyde solution for histology. The brain specimen was stained with hematoxylin-eosin to count cells in the prefrontal cortex and hippocampus. In experiment II, radial maze tests were done for 48 rats before any drug treatment and only after ketamine administration. Thereafter, haloperidol, bromocriptine, clonidine, nimodipine, tacrine, valproic acid, naloxone and fluoxetine were intramuscularly injected on every other day in addition to ketamine. Radial maze tests were repeated on every week for 6 weeks, and then rats were prepared by the same procedure for histology. Results : 1) Reaction times of radial maze tests of atropine-treated rats were significantly prolonged than those of normal aged(p<0.05) or normal adult controls(p<0.05). Cell numbers of prefrontal cortex & hippocampus in ketamine-treated rats were significantly reduced than those in normal aged (p<0.05) or normal adult controls(p<0.005). 2) Reduced cell numbers by ketamine became significantly raised by tacrine administration in prefrontal cortex & hippocampus(p<0.05), while there were no significant changes on radial maze tests. Cell numbers also tended to be raised by nimodipine, fluoxetine and haloperidol administration. Conclusions : In conclusion, the visuospatial memory disorders in ketamine-induced psychotic rats might be partly asso-ciated with aging process. Furthermore, the responses to the various drugs suggested cholinergic system might have an important role in the neurochemical mechanism of the cognitive dysfunction in ketamine-induced psychosis. Otherwise, calcium metabolism as well as serotonergic and dopaminergic systems seemed to be possibly related.

• Korean Journal of Veterinary Research
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• v.33 no.1
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• pp.71-80
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• 1993

The central nervous system depressant effect of xylazine and xylazine-ketamine was studied in chicken and mice. Intraperitoneal injection of xylazine(1~30 mg/kg) and xylazine(1~30 mg/kg)-ketamine(100 mg/kg) induced a loss of the righting reflex in chicken and mice, respectively. These effects of xylazine were dose-dependent. The results obtained were as follows; 1. The effect of xylazine-induced depression was antagonized by adrenergic antagonists having ${\alpha}_2$-blocking activity(yohimbine, tolazoline, piperoxan and phentolamine). 2. Yohimbine was most effective in the reduction of the CNS depression by xylazine. 3. Phenoxybenzamine and prazosin did not reduced CNS depression by xylazine in both species. 4. Labetalol (${\alpha}_1$, ${\beta}_1$-adrenergic antagonist) and propranolol(${\beta}$-adrenergic blocking agent) were not effective in reducing xylazine induced depression. 5. Cholinergic blocking agents (atropine and mecamylamine), a dopaminergic antagonist (Haloperidol), a histamine $H_1$-antagonist(chlorpheniramine), a histamine $H_2$-antagonist(cimetidine), a serotonergic-histamine $H_1$ antagonist(cyproheptadine) were not effective in reducing xylazine-induced depression. 6. Xylazine-induced depression is mediated by ${\alpha}_2$-adrenergic receptors and appears not to be involved in cholinergic, dopaminergic, serotonergic or histaminergic pathways.

• The Korean Journal of Pharmacology
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• v.23 no.2
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• pp.95-100
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• 1987

The effects of various drugs on muricide and hyperirritability induced by bilateral lesions of the nucleus accumbens septi (NAB) were investigated in comparison with those on aggression induced by midbrain raphe nuclei-lesioned rats (raphe) and olfactory bulbectomized rats (OB). Muricide in NAB, raphe and OB rats were markedly suppressed by atropine. Muricide in NAB and raphe rats were significantly suppressed by L-DOPA, L-5-HTP, but muricide in OB rats was scarcely suppressed by L-DOPA and L-5-HTP. Hyperirritability in NAB, raphe and OB rats were significantly reduced by L-DOPA and haloperidol but not suppressed by atropine. On the other hand, muricide in NAB rats was markedly suppressed by antidepressants, particularily, nomifensine, clomipramine and desipramine. Muricide in raphe rats was markedly inhibited by nomifensine and clomipramine but only slightly inhibited by desipramine. Muricide in OB rats was markedly suppressed by imipramine. Hyperirritability in NAB, raphe and OB rats were slightly suppressed by antidepressants. These results suggested that the pharmacological characteristics of aggression induced by NAB rats resembles that induced by raphe rats, but differs from that induced by OB rats. It is also suggested that employment of different types of experimentally induced muricide in rats can be useful for the evaluation of antidepressants.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.9 no.1
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• pp.98-104
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• 1998

A 12-year-old girl with a 6 year history of childhood-onset schizophrenia required 2 hospitalizations and long-term clozapine trial due to inadequate responses to combinations of typical neuroleptics and traditional treatments of schizophrenic disorder. On admission, she had continuous auditory and visual hallucinations, persecutory delusion, emotional instability, regression of behaviors including temper tantrums as well as specific developmental delays in learning, language, and motor coordination. The clozapine trial significantly reduced most of the positive symptoms, and facilitated in successful discharge from the hospital. During the 4 year clozapine treatment, no significant adverse reactions were noted, and she returned to a structured school setting with minimal degrees of schizophrenic symptoms. From this clinical experience, we suggest that clozapine might be safe and effective in treating treatment-refractory schizophrenic children.