Lack of G protein-coupled sigma receptors in rat brain membranes: receptor-mediated high-affinity GTPase activity and [35S]GTPgammaS binding studies.

Although sigma (sigma) receptors have been identified as an independent receptor family distinct from opioid and phencyclidine receptors, the physiological roles of these receptors are largely unknown. It is controversial whether there exist metabotropic sigma receptors that are coupled with heterotrimeric G proteins. In the present study, the stimulatory effects of sigma ligands on high-affinity GTPase activity and [35S]GTPgammaS binding were determined in the membranes prepared from rat cerebral cortex, hippocampus, and striatum. In either G protein activation assay, none of the sigma ligands examined had stimulatory effect in any brain regions, except for unambiguous concentration-dependent increase in [35S]GTPgammaS binding by (+)-3-(3-hydroxyphenyl)-N-(1-propyl) piperidine [(+)-3-PPP] in striatal membranes. However, the competition study clearly showed this response was mediated through dopamine D2-like receptors, but not sigma receptors. It is concluded that sigma receptors are not coupled to heterotrimeric G proteins, at least those of Gi/o type.

Association of structural polymorphisms in the human period3 gene with delayed sleep phase syndrome.

Recent progress in biological clock research has facilitated genetic analysis of circadian rhythm sleep disorders, such as delayed sleep phase syndrome (DSPS) and non-24-h sleep-wake syndrome (N-24). We analyzed the human period3 (hPer3) gene, one of the human homologs of the Drosophila clock-gene period (Per), as a possible candidate for rhythm disorder susceptibility. All of the coding exons in the hPer3 gene were screened for polymorphisms by a PCR-based strategy using genomic DNA samples from sleep disorder patients and control subjects. We identified six sequence variations with amino acid changes, of which five were common and predicted four haplotypes of the hPer3 gene. One of the haplotypes was significantly associated with DSPS (Bonferroni's corrected P = 0.037; odds ratio = 7.79; 95% CI 1.59-38.3) in our study population. Our results suggest that structural polymorphisms in the hPer3 gene may be implicated in the pathogenesis of DSPS.

Genetic polymorphisms of human melatonin 1b receptor gene in circadian rhythm sleep disorders and controls.

Recent studies suggest that melatonin 1b (Mel1b) receptor, as well as melatonin 1a (Mel1a) receptor, is involved in the modulation of circadian rhythms in mammals. Mutational analysis was performed in the entire coding region of the human Mel1b receptor gene using genomic DNA from sleep disorder subjects. We have identified two missense mutations, G24E and L66F. However, neither is likely to be associated with sleep disorders in our study population. One of the subjects with non-24-h sleep-wake syndrome carries missense mutations in both the Mel1a and Mel1b receptor genes.

Alleic variants of human melatonin 1a receptor: function and prevalence in subjects with circadian rhythm sleep disorders.

The human melatonin 1a (hMella) receptor gene was screened for mutations using genomic DNA samples from patients with circadian rhythm sleep disorders and control subjects by single strand conformational polymorphism analysis (SSCP). We found seven mutations, two of which predict amino acid changes R54W and A157V, respectively. The prevalence of the R54W variant and that of the A157V variant were several times more common in non-24-h sleep-wake syndrome subjects than among control subjects, although the incidence was not significant in our study group. When expressed in COS-7 cells, the R54W mutant receptor exhibited significantly reduced B(max) and slightly enhanced affinity (reduced K(d)) compared to the wild type receptor, while the A157V variant receptor showed similar binding characteristics to the wild type. The identification of variants in the hMella receptor will provide a useful tool for analyzing genetic predisposition toward various diseases related to melatonin function and to clarify the physiological role of melatonin receptors in humans.

Measurements by biphasic changes of the alpha band amplitude as indicators of arousal level.

The objective of this study was to develop a method of measuring arousal level by examining the change rates with activation of the alpha band amplitude using the concept of the inverted U-shaped pattern of transition of this amplitude. We investigated change rates by inspecting the electroencephalogram, and we evaluated their correlations with a criterion index of the arousal level (a reaction time measure), and other relevant basic parameters in 14 normal volunteers. In order to confirm that alpha band amplitude change followed an inverted U-shaped curve, we examined the transition of that index in a resting-and-relaxing condition. In the third session, the change rates upon stimulation and after resting had positive and negative correlations, respectively, with the reaction time measure, verifying that they are 'negative' and 'positive' arousal level indices. Further examinations were conducted for the third session. The change rates upon stimulation and after resting had negative correlations with each other. Neither of them had a significant correlation with the alpha band amplitude. Neither alpha band frequency, alpha band amplitude, or theta band amplitude, all of which are regarded as indices for intra-subject arousal level transition, had any significant correlation with the reaction time measure. These results revealed that the change rates of the alpha band amplitude are better indices for inter-individual arousal level variation than other conventional indices.

Effects of TJ-960 on Sternberg's paradigm results in epileptic patients.

OBJECTIVES: This study is aimed at investigating the effects of TJ-960 on cognitive function in epileptic patients. Sternberg's paradigm was used to examine the change in cognitive function, especially short-term memory, resulting from administration of TJ-960, along with the effects of the drug on seizures. SUBJECTS: The subjects of this investigation were 26 epileptic outpatients (14 males and 12 females; average age: 35 +/- 11 years old) of the Saitama Medical School Hospital, the Tokyo Medical and Dental University Hospital and the Tokyo University Hospital. The controls were 17 other epileptic outpatients (12 males and 5 females; average age: 40 +/- 12 years old) of the same hospitals. METHODS: The subjects were administered 7.5 g of TJ-960 per day for 8 weeks in addition to their previous medications. Immediately before the beginning of drug administration, and again after 8 weeks of administration, they were examined, using Sternberg's paradigm. The controls were examined at intervals of 8 weeks in the same manner as the subjects (i.e., no change in regimen). RESULTS: After 8 weeks of treatment with TJ-960, 8 of the subjects exhibited a greater than 25% decrease in the number of seizures. Seventeen cases showed no change, and one case showed exacerbation. The correct reaction times for Sternberg's paradigm in the group administered TJ-960 were 955 +/- 307 ms at the time of the first examination and 881 +/- 277 ms at the time of the second, and those of the control group were 845 +/- 288 ms for the first examination and 829 +/- 269 ms for the second. As these figures show, the correct reaction time was significantly shortened between the first and second examinations in the TJ-960 group. No change was exhibited in the sample reaction time between the first and second examination in either group. The difference in alpha wave power of the occipital region before and after the TJ-960 administration was significantly greater in the patients who showed improvement in Sternberg's paradigm as compared to the patients who remained unchanged in Sternberg's paradigm. In addition, the results for the theta wave power were opposite to those of alpha waves. As mentioned above, TJ-960 was presumed to have the effect of improving the cognitive function in epileptic patients.

Treatment resistant chronic psychopathology and CT scans in schizophrenia.

In order to examine the relationship between the neuroleptic resistant chronic psychopathology and CT findings in schizophrenia, 25 schizophrenics who had been treated well and were in a stable condition were assessed for positive and negative symptoms, CT findings, medication, and the clinical course of illness. Correlational analysis showed that there was a group of patients who had comparatively small ventricles and presented treatment resistant positive symptoms, and another group of patients who had larger ventricles and lacked positive symptoms. Negative symptoms showed a tendency toward positive correlation with atrophic CT changes of cortices. Literature on CT findings and symptomatology was critically reviewed. The importance of the more chronic positive symptoms correlating to CT findings in schizophrenia were discussed.