Early onset of treatment effects with oral risperidone

BACKGROUND: The dogma of a delayed onset of antipsychotic treatment effects has been maintained over the past decades. However, recent studies have challenged this concept. We therefore performed an analysis of the onset of antipsychotic treatment effects in a sample of acutely decompensated patients with schizophrenia. METHODS: In this observational study, 48 inpatients with acutely decompensated schizophrenia were offered antipsychotic treatment with oral risperidone. PANSS-ratings were obtained on day 0, day 1, day 3, day 7 and day 14. RESULTS: Significant effects of treatment were already present on day 1 and continued throughout the study. The PANSS positive subscore and the PANSS total score improved significantly more than the PANSS negative subscore. CONCLUSION: Our results are consistent with the growing number of studies suggesting an early onset of antipsychotic treatment effects. However, non-pharmacological effects of treatment also need to be taken into consideration

向精神薬服用患者の突然死症例におけるカリウムイオンチャネルに関する分子生物学的解析：QT延長症候群関連遺伝子の多型が危険因子となり得るか？

Psychotropic drugs can pose the risk of acquired long QT syndrome (LQTS). Unexpected autopsy-negative sudden death in patients taking psychotropic drugs may be associated with prolonged QT intervals and life-threatening arrhythmias. We analyzed genes that encode for cardiac ion channels and potentially associated with LQTS, examining specifically the potassium channel genes KCNQ1 and KCNH2 in 10 cases of sudden death involving patients administered psychotropic medication in which autopsy findings identified no clear cause of death. We amplified and sequenced all exons of KCNQ1 and KCNH2, identifying G643S, missense polymorphism in KCNQ1, in 6 of the 10 cases. A study analysis indicated that only 11% of 381 healthy Japanese individuals carry this polymorphism. Reports of previous functional analyses indicate that the G643S polymorphism in the KCNQ1 potassium channel protein causes mild IKs channel dysfunction. Our present study suggests that administering psychotropic drug therapy to individuals carrying the G643S polymorphism may heighten the risk of prolonged QT intervals and life-threatening arrhythmias. Thus, screening for the G643S polymorphism before prescribing psychotropic drugs may help reduce the risk of unexpected sudden death2013博士（歯学）松本歯科大

Acetylcholine imaging in psychosis

Core symptoms of psychosis include delusions, hallucinations, motor symptoms, and cognitive impairments. The cholinergic system has been increasingly implied in the pathophysiology of psychotic disorders. PET and SPECT imaging can be useful tools to increase our insight in the role of the neurotransmitter acetylcholine in psychosis. In this chapter we will first globally describe cholinergic neurotransmission and the function of the nicotinic and muscarinic receptors. Second, we will provide an overview of PET and SPECT studies examining the cholinergic system in psychosis. Finally, we will briefly discuss the results of these studies as well as future directions

Altered M1 Muscarinic Acetylcholine Receptor (CHRM1)-Gαq/11 Coupling in a Schizophrenia Endophenotype

Alterations in muscarinic acetylcholine receptor (CHRM) populations have been implicated in the pathology of schizophrenia. Here we have assessed whether the receptor function of the M1 subtype (CHRM1) is altered in a sub-population of patients with schizophrenia, defined by marked (60–80%) reductions in cortical [3H]-pirenzepine (PZP) binding, and termed ‘muscarinic receptor-deficit schizophrenia’ (MRDS). Using a [35S]-GTPγS-Gαq/11 immunocapture method we have assessed whether CHRM1 signalling in human cortex (Brodmann area 9 (BA9)) is altered in post mortem tissue from a MRDS group compared with a subgroup of patients with schizophrenia displaying normal PZP binding, and controls with no known history of psychiatric or neurological disorders. The CHRM agonist (oxotremorine-M) and a CHRM1-selective agonist (AC-42) increased Gαq/11-[35S]-GTPγS binding, with AC-42 producing responses that were ~50% of those maximally evoked by the full agonist, oxotremorine-M, in control and subgroups of patients with schizophrenia. However, the potency of oxotremorine-M to stimulate Gαq/11-[35S]-GTPγS binding was significantly decreased in the MRDS group (pEC50 (M)=5.69±0.16) compared with the control group (6.17±0.10) and the non-MRDS group (6.05±0.07). The levels of Gαq/11 protein present in BA9 did not vary with diagnosis. Maximal oxotremorine-M-stimulated Gαq/11-[35S]-GTPγS binding in BA9 membranes was significantly increased in the MRDS group compared with the control group. Similar, though non-statistically significant, trends were observed for AC-42. These data provide evidence that both orthosterically and allosterically acting CHRM agonists can stimulate a receptor-driven functional response ([35S]-GTPγS binding to Gαq/11) in membranes prepared from post mortem human dorsolateral prefrontal cortex of patients with schizophrenia and controls . Furthermore, in a subgroup of patients with schizophrenia displaying markedly decreased PZP binding (MRDS) we have shown that although agonist potency may decrease, the efficacy of CHRM1-Gαq/11 coupling increases, suggesting an adaptative change in receptor-G protein coupling efficiency in this endophenotype of patients with schizophrenia