To determine the factors underlying suicide in Akita prefecture, a questionnaire survey was conducted among members of the Akita Prefectural Medical Association (APMA), regarding suicide cases they attended. During the investigation period (1 July 2001-30 June 2002), the total number of suicide cases was 243 (138 completed, 105 attempted). Significant differences were identified between completed and attempted suicide groups in terms of gender, age distribution, and suicidal methods. Specifically, in the completed suicide group, the number of male completers exceeded that of female completers, the number of middle-aged or elderly completers was high, and the majority of completed suicide cases involved hanging as the suicide method. Conversely, in the attempted suicide group, the number of female attempters exceeded that of male attempters, younger attempters were frequent, hanging was rare, and drug overdose or cutting was common. In addition, the number of cases involving a history of previous suicide attempts was significantly higher in the attempted suicide group than in the completed suicide group. The results of the present study support the concept that the completed and attempted suicide groups are essentially of a different nature. Furthermore, the number of cases involving a history of previous suicide attempts was found to be significantly lower in the completed suicide group than in the attempted suicide group. This result indicates the difficulty in decreasing the number of completed suicides by simply providing intervention and care for individuals who have attempted suicide.

Akita Prefecture currently has the highest rate of suicide in Japan. Given this alarming statistic, investigation of the underlying causes of suicide and identification of strategies for suicide prevention are imperative. Members of the Akita Prefectural Medical Association (APMA) see most of the individuals who commit suicides in Akita Prefecture, so data from the APMA would prove advantageous in any investigation of suicides. In this study, members of the APMA who had attended to individuals who had committed suicide were asked to complete a questionnaire about the case to determine the factors underlying suicide in Akita Prefecture. From 1 July 2001 to 30 June 2002, a total of 138 cases (102 males, 36 females) of suicide were reported. Most suicide cases were of 50-69 year olds. Many cases involved relatively lethal methods (such as hanging). Most suicides were performed at home and at a time when the rest of the family was asleep or absent. The most common complaint appeared to be economic-related problems. Depressive disorder was the most common psychiatric disorder, and many cases displayed high depressive trait scores. The present results do not exclude the possibility that economic-related problems are playing a major role in recent increases in suicide numbers. However, strategies for dealing with depression as well as economic-related problems are considered important.

A glycolipid having GalNAc alpha1-3GalNAc in the terminal increases a behavior climbing in a depression model, mouse forced swimming. Antidepressants, which sometimes induce hypomanic state in patients, increase the glycolipid and an anti-manic substance lithium decreases the glycolipid in mice. We detected the humoral GalNAc alpha1-3GalNAc-lipid reactivity of humans in different affective states. Although the reactivity was also showed in serums of the depression patients and the volunteers without affective disorders, the reactivity was remarkably increased in serums of hypomania patients. These strongly suggest that the humoral glycolipid increased the activities of the hypomania patients, but did not relate to the decrease of the activities in the depression patients.

Slip-down from a raised platform was previously found in mice treated with morphine, and this behavior was also recognized in mice treated with a monoamine releaser methamphetamine. Pharmacological examination on the slip-down indicated that the behavior was induced by receptor stimulations by D2 agonist PPHT and 5HT-2 agonist DOI. In mice treated with PPHT, antagonists of D1, alpha2, 5HT-2 and opioid mu and kappa suppressed the behavior. In mice treated with DOI, antagonists of D1, alpha2, 5HT-1A, 5HT-3 and opioid mu and delta suppressed the behavior. These present findings suggest that the slip-down was mainly induced by opioid mu receptor activity regulated with monoamine activities. When the slip-down is considered as an anxious behavior, it may be also suggested that the anxiety induced by 5-HT activities furthermore stimulated the behavior via the other opioid receptor activities.

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