Protein Kinase C Activity and Delayed Recovery of Sleep-Wake Cycle in Mouse Model of Bipolar Disorder

OBJECTIVE

Previous studies reported the delayed recovery group after circadian rhythm disruption in mice showed higher quinpiroleinduced locomotor activity. This study aimed to compare not only Protein Kinase C (PKC) activities in frontal, striatal, hippocampus and cerebellum, but also relative PKC activity ratios among brain regions according to recovery of circadian rhythm.

METHODS

The circadian rhythm disruption protocol was applied to eight-week-old twenty male Institute Cancer Research mice. The circadian rhythm recovery patterns were collected through motor activities measured by Mlog system. Depressive and manic proneness were examined by forced swim test and quinpirole-induced open field test respectively. Enzyme-linked immunosorbent assay was employed to measure PKC activities.

RESULTS

The delayed recovery group presented greater locomotor activities than the early recovery group (p=0.033). The delayed recovery group had significantly lower frontal PKC activity than the other (p=0.041). The former showed lower frontal/cerebellar PKC activity ratio (p=0.047) but higher striatal/frontal (p=0.038) and hippocampal/frontal (p=0.007) PKC activities ratios than the latter.

CONCLUSION

These findings support potential mechanism of delayed recovery after circadian disruption in bipolar animal model could be an alteration of relative PKC activities among mood regulation related brain regions. It is required to investigate the PKC downstream signaling related to the delayed recovery pattern.

Times to Discontinue Antidepressants Over 6 Months in Patients with Major Depressive Disorder

OBJECTIVE

The aim of the present study was to investigate differences in discontinuation time among antidepressants and total antidepressant discontinuation rate of patients with depression over a 6 month period in a naturalistic treatment setting.

METHODS

We reviewed the medical records of 900 patients with major depressive disorder who were initially prescribed only one kind of antidepressant. The prescribed antidepressants and the reasons for discontinuation were surveyed at baseline and every 4 weeks during the 24 week study. We investigated the discontinuation rate and the mean time to discontinuation among six antidepressants groups.

RESULTS

Mean and median overall discontinuation times were 13.8 and 12 weeks, respectively. Sertraline and escitalopram had longer discontinuation times than that of fluoxetine, and patients who used sertraline discontinued use significantly later than those taking mirtazapine. No differences in discontinuation rate were observed after 24 weeks among these antidepressants. About 73% of patients discontinued antidepressant treatment after 24 weeks.

CONCLUSION

Sertraline and escitalopram tended to have longer mean times to discontinuation, although no difference in discontinuation rate was detected between antidepressants after 24 weeks. About three-quarters of patients discontinued antidepressant maintenance therapy after 24 weeks.

SCL-90-R and 16PF profiles of senior high school students with excessive internet use

OBJECTIVE

To investigate the psychiatric symptomatology and personality characteristics of Korean senior high school students considered to use the Internet to excess.

METHOD

We administered a questionnaire packet to students that included 4 measures. These measures included a questionnaire on Internet use patterns during the previous month, the Internet Addiction Test (IAT), the Symptom Checklist-90-R (SCL-90-R), and the Sixteen Personality Factor Questionnaire (16PF). A total of 328 students, aged 15 to 19 years, participated in the study.

RESULTS

Students were divided into 4 Internet user groups according to their IAT total scores: nonusers (n = 59, 18.0%), minimal users (n = 155, 47.3%), moderate users (n = 98, 29.9%), and excessive users (n = 16, 4.9%). The SCL-90-R showed that the excessive users group, when compared with the other groups in this study, reported the highest levels of symptomatology. The 16PF also revealed that excessive users were easily affected by feeling, emotionally less stable, imaginative, absorbed in thought, self-sufficient, experimenting, and preferred their own decisions.

CONCLUSIONS

This study suggests that senior high school students who use the Internet to excess report and subsequently exhibit significantly more psychiatric symptoms than students who use the Internet less frequently. In addition, excessive users appear to have a distinctive personality profile when compared with nonusers, minimal, and moderate users.