Validation of Wistar-Kyoto rats kept in solitary housing as an animal model for depression using voxel-based morphometry.

Major depressive disorder is a common psychiatric condition often resistant to medication. The Wistar-Kyoto (WKY) rat has been suggested as an animal model of depression; however, it is still challenging to translate results from animal models into humans. Solitary housing is a mild stress paradigm that can simulate the environment of depressive patients with limited social activity due to symptoms. We used voxel-based morphometry to associate the solitary-housed WKY (sWKY) rat model with data from previous human studies and validated our results with behavioural studies. As a result, atrophy in sWKY rats was detected in the ventral hippocampus, caudate putamen, lateral septum, cerebellar vermis, and cerebellar nuclei (p < 0.05, corrected for family-wise error rate). Locomotor behaviour was negatively correlated with habenula volume and positively correlated with atrophy of the cerebellar vermis. In addition, sWKY rats showed depletion of sucrose consumption not after reward habituation but without reward habituation. Although the application of sWKY rats in a study of anhedonia might be limited, we observed some similarities between the regions of brain atrophy in sWKY rats and humans with depression, supporting the translation of sWKY rat studies to humans.

The Role of the Thalamus in Post-Traumatic Stress Disorder.

Post-traumatic stress disorder (PTSD) has a high lifetime prevalence and is one of the more serious challenges in mental health care. Fear-conditioned learning involving the amygdala has been thought to be one of the main causative factors; however, recent studies have reported abnormalities in the thalamus of PTSD patients, which may explain the mechanism of interventions such as eye movement desensitization and reprocessing (EMDR). Therefore, I conducted a miniature literature review on the potential contribution of the thalamus to the pathogenesis of PTSD and the validation of therapeutic approaches. As a result, we noticed the importance of the retinotectal pathway (superior colliculus-pulvinar-amygdala connection) and discussed therapeutic indicators.

Brain atrophy in the visual cortex and thalamus induced by severe stress in animal model.

Psychological stress induces many diseases including post-traumatic stress disorder (PTSD); however, the causal relationship between stress and brain atrophy has not been clarified. Applying single-prolonged stress (SPS) to explore the global effect of severe stress, we performed brain magnetic resonance imaging (MRI) acquisition and Voxel-based morphometry (VBM). Significant atrophy was detected in the bilateral thalamus and right visual cortex. Fluorescent immunohistochemistry for Iba-1 as the marker of activated microglia indicates regional microglial activation as stress-reaction in these atrophic areas. These data certify the impact of severe psychological stress on the atrophy of the visual cortex and the thalamus. Unexpectedly, these results are similar to chronic neuropathic pain rather than PTSD clinical research. We believe that some sensitisation mechanism from severe stress-induced atrophy in the visual cortex and thalamus, and the functional defect of the visual system may be a potential therapeutic target for stress-related diseases.

[A case of intractable recurrent corneal erosion caused by Munchausen syndrome].

OBJECT: We report a case of intractable recurrent corneal erosion that was unresponsive to any medication, but was cured by psychiatric care after diagnosis of Munchausen syndrome. CASE: The patient, a 35-year-old female, who developed pain in her left eye in July, 20 XX, was diagnosed with epidemic keratoconjunctivitis at the hospital where she worked as a nurse. Despite medication, the eye condition gradually worsened. After undergoing examination at many medical institutions, she came to our hospital on October 6, 20 XX. Her left eye manifested superficial punctate keratitis, then exhibited recurring corneal erosion. The eye condition was intractable, total corneal epithelial defect ultimately occurring on December 30. Subsequently, a bottle of hydrochloric acid oxybuprocaine eyedrops was found under her pillow. We therefore suspected that the corneal erosion was due to self-inflicted injury. She consulted a psychiatrist, and was diagnosed with Munchausen syndrome. After about 2 months of therapy in which she was prevented from touching the eye(eye patch etc.), her eye condition improved. CONCLUSION: This case was not diagnosed as Munchausen syndrome for 5 months. In cases of intractable corneal erosion, the possibility of self-injury should be considered.