Panic disorder patients have reduced cyclic AMP in platelets

Hyper-Activated Brain Resting-State Network and Mismatch Negativity Deficit in Schizophrenia With Auditory Verbal Hallucination Revealed by an Event-Related Potential Evidence

Schizophrenia is a holergasia with unclear mechanism and high heterogeneity. Auditory verbal hallucination (AVH) study might help in understanding schizophrenia from the perspective of individual symptoms. This study aimed to investigate the activities of the resting-state networks (RSN) in the electroencephalogram (EEG) and mismatch negativity (MMN) in task-related state of schizophrenia patients with AVH. We recruited 30 schizophrenia patients without any medication for more than 4 weeks (15 AVH patients and 15 Non-AVH patients) and 15 healthy controls. We recorded the EEG data of the participants in the resting-state for 7 min and the event-related potential (ERP) data under an auditory oddball paradigm. In the resting-state EEG network, AVH patients exhibited a higher clustering coefficient than Non-AVH patients and healthy controls on delta and beta bands and a shorter characteristic path length than Non-AVH patients and healthy controls on all frequency bands. For ERP data, AVH patients showed a lower MMN amplitude than healthy controls (p = 0.017) and Non-AVH patients (p = 0.033). What's more, MMN amplitude was positively correlated with clustering coefficient, and negatively correlated with characteristic path length on delta, theta, beta and gamma band in AVH patients. Our results indicate that AVH patients showed a hyper-activity in resting-state and may have impaired higher-order auditory expectations in the task-related state than healthy controls and Non-AVH patients. And it seems reasonable to conclude that the formation of AVH may occupy certain brain resources and compete for brain resources with external auditory stimuli.

Neuronal nitric oxide synthase (NOS1) and its adaptor, NOS1AP, as a genetic risk factors for psychiatric disorders

Nitric oxide (NO) is a gaseous transmitter produced by nitric oxide synthases (NOSs). The neuronal isoform (NOS-I, encoded by NOS1) is the main source of NO in the central nervous system (CNS). Animal studies suggest that nitrinergic dysregulation may lead to behavioral abnormalities. Unfortunately, the large number of animal studies is not adequately reflected by publications concerning humans. These include post-mortem studies, determination of biomarkers, and genetic association studies. Here, we review the evidence for the role of NO in psychiatric disorders by focusing on the human NOS1 gene as well as biomarker studies. Owing to the complex regulation of NOS1 and the varying function of NOS-I in different brain regions, no simple, unidirectional association is expected. Rather, the 'where, when and how much' of NO formation is decisive. Present data, although still preliminary and partially conflicting, suggest that genetically driven reduced NO signaling in the prefrontal cortex is associated with schizophrenia and cognition. Both NOS1 and its interaction partner NOS1AP have a role therein. Also, reduced NOS1 expression in the striatum determined by a length polymorphism in a NOS1 promoter (NOS1 ex1f-VNTR) goes along with a variety of impulsive behaviors. An association of NOS1 with mood disorders, suggested by animal models, is less clear on the genetic level; however, NO metabolites in blood may serve as biomarkers for major depression and bipolar disorder. As the nitrinergic system comprises a relevant target for pharmacological interventions, further studies are warranted not only to elucidate the pathophysiology of mental disorders, but also to evaluate NO function as a biomarker.

Neuroglial Transmission

Neuroglia, the "glue" that fills the space between neurons in the central nervous system, takes active part in nerve cell signaling. Neuroglial cells, astroglia, oligodendroglia, and microglia, are together about as numerous as neurons in the brain as a whole, and in the cerebral cortex grey matter, but the proportion varies widely among brain regions. Glial volume, however, is less than one-fifth of the tissue volume in grey matter. When stimulated by neurons or other cells, neuroglial cells release gliotransmitters by exocytosis, similar to neurotransmitter release from nerve endings, or by carrier-mediated transport or channel flux through the plasma membrane. Gliotransmitters include the common neurotransmitters glutamate and GABA, the nonstandard amino acid d-serine, the high-energy phosphate ATP, and l-lactate. The latter molecule is a "buffer" between glycolytic and oxidative metabolism as well as a signaling substance recently shown to act on specific lactate receptors in the brain. Complementing neurotransmission at a synapse, neuroglial transmission often implies diffusion of the transmitter over a longer distance and concurs with the concept of volume transmission. Transmission from glia modulates synaptic neurotransmission based on energetic and other local conditions in a volume of tissue surrounding the individual synapse. Neuroglial transmission appears to contribute significantly to brain functions such as memory, as well as to prevalent neuropathologies.

Altered diurnal variation of nitric oxide production in patients with panic disorder

The aim of this prospective study was to investigate the diurnal change in serum nitric oxide (NO) levels in active and remission phases of patients with panic disorder. This study included 15 patients fulfilling the criteria for panic disorder of Diagnostic and Statistical Manual of Mental Disorders--Fourth Edition and 15 healthy controls matched for age and sex. All patients were receiving a selective serotonin reuptake inhibitor at therapeutic doses. The serum nitrite and nitrate levels of subjects were determined at 10:00 a.m. after overnight fasting and at 3:00 p.m. 2 hours after lunch. NO levels of all patients measured in the morning were significantly higher than those of controls. The patients were also divided into active and remission groups according to clinical status and Panic Agoraphobia Scale's cut-off point. There were no statistically significant differences in serum nitrite and nitrate levels of the active group between the 10:00 a.m. and 3:00 p.m. measurements. In contrast, statistically significant differences were found in the serum levels of nitrite (p<0.05) and nitrate (p<0.05) in the remission group. Notably, the afternoon nitrite and nitrate levels of the remission group were higher than those of the morning levels as seen in control subjects. Thus, diurnal variation of NO production is altered in patients with panic disorder but is resumed in the remission phase. The present study suggests that serum NO levels are a good marker for evaluation of panic disorder.

Serotonin-mediated cyclic AMP inhibitory pathway in platelets of patients affected by panic disorder

Cyclic adenosine monophosphate (cAMP) pathway abnormalities have been suggested to be involved in anxiety disorders including panic (PD). The present study sought at investigating the downstream inhibitory adenylyl cyclase (AC) pathway activated by 5-HT in platelets obtained from 22 patients with a diagnosis of PD versus 22 healthy volunteers. In PD patients, a significant impairment of 5-HT potency to inhibit AC was observed. One month of treatment with paroxetine induced a significant increase of 5-HT potency in T1 patients close to the control values. [(35)S]GTPgammaS binding studies showed that in PD patients, a reduction of 5-HT receptor-G protein coupling occurred without any significant changes in G protein levels. These findings demonstrated that (1) a reduction of the inhibitory AC pathway activated by 5-HT occurred in platelets from PD patients; (2) the reduced 5-HT responsiveness in PD was related to an impairment of 5-HT receptor-G protein coupling, and (3) after 1 month of treatment with paroxetine, such a dysfunction significantly reversed together with a significant improvement of clinical symptoms.