Light therapy improved depression-like behavior induced by chronic unpredictable mild stress in Mongolian gerbils.

Progress has been made in elucidating the mechanism by which light modulates depressive-like behaviors. However, almost all of these studies ignore an important issue, namely, that examining the effects of light therapy in nocturnal animals may be difficult because the influences of light on behavioral responses differ between nocturnal and diurnal animals. To date, few diurnal rodents have been utilized to establish animal models that closely mimic clinical depression. Herein, the chronic unpredictable mild stress model, which is the most representative, reliable, and effective rodent model of depression, was implemented in diurnal Mongolian gerbils for the first time. The gerbils were subjected to two hours of light therapy or fluoxetine treatment for 2 weeks. Our work revealed that Mongolian gerbils subjected to chronic unpredictable mild stress showed depression-like behaviors. Interestingly, we also found that light therapy improved anhedonic behavior more effectively than fluoxetine after two weeks of treatment. In summary, our study is the first to use diurnal Mongolian gerbils, which have the same circadian rhythm as humans, to establish an effective, economical, and practical animal model of depression and confirmed that light therapy could improve depression-like behavior more effectively than fluoxetine to some extent in diurnal Mongolian gerbils, which establishes a good foundation for clarifying the neural mechanism of light therapy for depression.

Completed Suicide With Violent and Non-violent Methods by the Elderly in Rural China: A Psychological Autopsy Study.

Background: Late-life suicide is a severe public health problem in rural China; however, knowledge regarding the specific characteristics and risk factors for completed suicide via violent and non-violent methods among elderly individuals in rural China is limited. Methods: Subjects aged 60 years or older were selected from rural areas in Shandong, Hunan, and Guangxi provinces in China. This study was a 1:1 matched case-control design conducted by using the psychological autopsy method. Results: According to the univariate analyses, the presence of mental disorder, higher degree of depression, loneliness, lack of social support, hopelessness, impulsivity, and increased quantity of life events were associated with suicide in both violent and non-violent methods. For violent suicide, another risk factor was the lack of pesticides at home. For non-violent suicide, other risk factors were not currently married, family suicide history, and alcohol use disorder (P < 0.05). Variables that remained in the logistic regression model were the severity of depressive symptoms for both violent and non-violent suicide. For non-violent suicide, the degree of hopelessness was another independent risk factor. In addition, violent suicides were more likely to lack pesticides at home, choose the spring season and have an increased quantity of life events than those who died by suicide via non-violent methods. Conclusion: The major risk factor for both violent and non-violent suicide was the severity of depressive symptoms. Suicide prevention measures that focus on depression among this vulnerable population are urgently needed. Moreover, the characteristics of suicides via violent methods differed from those via non-violent methods among elderly individuals. Suicide prevention efforts should be tailored to the specific characteristics of the different suicide methods utilized by older adults in rural areas.

Suicide Means Used by the Older Adults in Rural China: A Comparison Between Those Using Pesticides and Other Means.

BACKGROUND: The most frequently used means of committing suicide was pesticide poisoning in rural China, yet little is known about the characteristics and risk factors for suicides committed with pesticides compared to those committed via other means in older adults. METHODS: The participants were 242 older adults (aged 60 or older) who had committed suicide in the rural areas of 3 provinces (Shandong, Hunan, and Guangxi) in China. This study was conducted using the psychological autopsy (PA) method. RESULTS: In univariate analyses, no statistically significant differences were found between those who committed suicide with pesticide or with other means in terms of demographic and clinical variables except age, prevalence of mental disorders, suicidal intent, number of recent life events, social support, hopelessness, impulsivity, and depressive symptoms (P > .05); age, history of suicide attempts, having pesticides available at home, the total number of life events, and the number of long-term life events were significantly different (P < .05) between the 2 groups. In multivariate logistic regression model, the factors associated with committing suicide with pesticides were the availability of pesticides at home (odds ratio [OR] = 3.48, 95% confidence interval [CI]: 1.99-6.08) and the number of long-term life events (OR = 0.87, 95% CI: 0.78-0.97). CONCLUSION: The older adults who committed suicide by pesticides and those using other means are probably the same population. The main determinant of choosing pesticides as suicide means was likely the availability of pesticides at home. Suicide risk among older adults might be reduced by placing appropriate restrictions on access to pesticides.

Norepinephrine Induces PTSD-Like Memory Impairments via Regulation of the ß-Adrenoceptor-cAMP/PKA and CaMK II/PKC Systems in the Basolateral Amygdala.

Glucocorticoids (GCs) can modulate the memory enhancement process during stressful events, and this modulation requires arousal-induced norepinephrine (NE) activation in the basolateral amygdale (BLA). Our previous study found that an intrahippocampal infusion of propranolol dose-dependently induced post-traumatic stress disorder (PTSD)-like memory impairments. To explore the role of the noradrenergic system of the BLA in PTSD-like memory impairment, we injected various doses of NE into the BLA. We found that only a specific quantity of NE (0.3 µg) could induce PTSD-like memory impairments, accompanied by a reduction in phosphorylation of GluR1 at Ser845 and Ser831. Moreover, this phenomenon could be blocked by a protein kinase A (PKA) inhibitor or calcium/calmodulin-dependent protein kinase II (CaMK II) inhibitor. These findings demonstrate that NE could induce PTSD-like memory impairments via regulation of the ß-adrenoceptor receptor (ß-AR)-3',5'-cyclic monophosphate (cAMP)/PKA and CaMK II/PKC signaling pathways.

Propranolol can induce PTSD-like memory impairments in rats.

Introduction: One hallmark symptom of post-traumatic stress disorder (PTSD) is an inability to restrict fear responses to the appropriate predictor. An infusion of glucocorticoids (GCs) after a high-intensity shock has been shown to induce PTSD-like memory impairments. In addition to GCs, noradrenergic signalling is also recognized as a key biomarker underlying PTSD symptomatology. Methods: To explore the role of the noradrenergic system in PTSD-like memory impairments, in this study, various doses of the ß-adrenoceptor antagonist propranolol were systemically or bilaterally injected into the dorsal hippocampus immediately after unpaired cue-shock contextual fear conditioning, and then the rats were tested 24 h later. Results: Interestingly, we found that only low-dose propranolol could induce PTSD-like memory impairments, as rats showed reduced freezing to the correct predictor and generalized fear responses to the safe cues, accompanied by increased NE levels in the hippocampus and altered neural activity within the frontal-subcortical circuit. Conclusion: These findings demonstrate that the noradrenergic system is involved in regulating the consolidation of contextual fear memory and that propranolol can dose-dependently induce PTSD-like memory impairments.

[Comparison of Pattern-pulse and Pattern-reversal Multifocal Visual Evoked Potentials in Normal Individuals].

OBJECTIVE: To compare pattern-pulse multifocal visual evoked potential (PPmfVEP) with pattern-reversal multifocal visual evoked potential (PRmfVEP), and to investigate the symmetry of mfVEP between both eyes in normal individuals. METHODS: The multifocal Vision Monitor was used to observe the mfVEP. T-test and ANOVA were used to analyze P1 wave, amplitude and signal noise ratios (SNR) of two mfVEPs. RESULTS: The SNR and the P1 amplitude reached the maximum at the central visual field and decreased with the increase of eccentricity, and then decreased slowly. The amplitude of the PPmfVEP was significantly smaller than the PRmfVEP in the central retina, while in the peripheral retina the result was exactly the opposite. SNR and amplitude of the PRmfVEP showed no statistical difference in both eyes (P > 0.05). The variance of the amplitude at the same side of visual field was larger than that at the symmetrical visual quadrant. CONCLUSION: mfVEP can reflect the visual function in different parts of retina objectively and exactly. PPmfVEP reflect the vision function of the central retina better than PRmfVEP. The stability of PPmfVEP is better than PRmfVEP in the central retina, while the result is opposite in the peripheral retina. The mfVEP is symmetrical in both eyes of the same individual.

[The evaluation of SCI by TMS-MEP and its forensic significance].

OBJECTIVE: To find an objective and accurate examination for evaluation of spinal cord injury (SCI) in forensic clinical medicine. METHODS: The onset latency of cortex, peak latency of N1, central motor conduction time (CMCT) and wave width of the abductor pollicis brevis and the anterior tibialis were calculated by transcranial magnetic stimulation-motor evoked potential (TMS-MEP). The data of 68 patients suffered from SCI including 23 cervical levels and 45 thoracolumbar levels were collected and compared with that of 30 normal controls. RESULTS: In experimental group, when the muscle strength of the abductor pollicis brevis or the anterior tibialis decreased or disappeared, the onset latency of cortex, the peak latency of N1, and CMCT prolonged and the wave width broadened. And these indexes of grade 2 and 3 muscle strength in experimental group were higher than that in the control group (P < 0.05). CONCLUSION: The TMS-MEP can determine directly and objectively the motor functional status of pyramidal tract of spinal cord in order to provide more accurate and objective evidences in forensic medicine.