Perineuronal oligodendrocytes in health and disease: the journey so far

Perineuronal oligodendrocytes (pn-Ols) are located in the cerebral gray matter in close proximity to neuronal perikarya and less frequently near dendrites and neurites. Although their morphology is indistinguishable from that of other oligodendrocytes, it is not known if pn-Ols have a similar or different cell signature from that of typical myelinating oligodendroglial cells. In this review, we discussed the potential roles of these cells in myelination under normal and pathophysiologic conditions as functional and nutritional supporters of neurons, as restrainers of neuronal firing, and as possible players in glutamate-glutamine homeostasis. We also highlighted the occurrences in which perineuronal oligodendroglia are altered, such as in experimental demyelination, multiple sclerosis, cerebral ischemia, epilepsy, Alzheimer's disease, schizophrenia, major depression, and bipolar disorder311899

Assessment of insulin resistance among drug-naive patients with first-episode schizophrenia in the context of hormonal stress axis activation

Before the introduction of antipsychotics, links between schizophrenia and abnormal glucose metabolism levels were found in the late 1800s as an increased prevalence of diabetes in families with a history of “insanity.”1 Furthermore, it is known that some patients with psychosis require higher dosages than other patients when applying insulin therapy, suggestive of insulin resistance.2 A recent meta-analysis by Pillinger et al1 assessed insulin resistance and found an elevated homeostatic model assessment of insulin resistance (HOMA-IR) among drug-naive patients with first-episode schizophrenia (n = 560) compared with controls (n = 450).1 They highlighted hormonal stress axis activation and lifestyle factors as potential confounders.1 Stress hormones, such as cortisol and catecholamines, are catabolic and functional antagonists of insulin. Antipsychotic-naive individuals with first-episode psychosis exhibit higher baseline cortisol levels and a blunted cortisol awakening response compared with controls.1,3 To test whether insulin resistance in schizophrenia can be discerned from stress-related and medication effects, we assessed HOMA-IR and stress hormone levels among drug-naive patients with first-episode schizophrenia and matched controls

VGF Expression by Monocytes in Patients with Alzheimer’s Disease and Vascular Dementia

Because its secretion is changed in cerebrospinal fluid and peripheral blood, the neuronal polypeptide VGF (nonacronymic) has been discussed as a biomarker for neuropsychiatric disorders. We have shown an enhanced VGF expression by T-cells from Alzheimer's disease (AD) patients. In this study, we investigated the VGF expression by peripheral monocytes in 38 AD patients, 5 patients with vascular dementia (VD), and 20 neuropsychiatrically healthy individuals using flow cytometry. We determined an enhanced number of VGF-expressing monocytes in VD patients compared to AD patients. VGF+CD14+ monocytes were not correlated with age, body mass index, Mini-Mental State Examination (MMSE), or Q albumin. These preliminary data support findings indicating that VGF might play a role as a peripheral biomarker in VD