Localization of Nitric Oxide Synthase-containing Neurons in the Bat Visual Cortex and Co-localization with Calcium-binding Proteins

Neuronal nitric oxide synthase and affective disorders

Affective disorders including major depressive disorder (MDD), bipolar disorder (BPD), and general anxiety affect more than 10% of population in the world. Notably, neuronal nitric oxide synthase (nNOS), a downstream signal molecule of N-methyl-D-aspartate receptors (NMDARs) activation, is abundant in many regions of the brain such as the prefrontal cortex (PFC), hippocampus, amygdala, dorsal raphe nucleus (DRN), locus coeruleus (LC), and hypothalamus, which are closely associated with the pathophysiology of affective disorders. Decreased levels of the neurotransmitters including 5-hydroxytryptamine or serotonin (5-HT), noradrenalin (NA), and dopamine (DA) as well as hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis are common pathological changes of MDD, BPD, and anxiety. Increasing data suggests that nNOS in the hippocampus play a crucial role in the etiology of MDD whereas nNOS-related dysregulation of the nitrergic system in the LC is closely associated with the pathogenesis of BPD. Moreover, hippocampal nNOS is implicated in the role of serotonin receptor 1 A (5-HTR1 A) in modulating anxiety behaviors. Augment of nNOS and its carboxy-terminal PDZ ligand (CAPON) complex mediate stress-induced anxiety and disrupting the nNOS-CAPON interaction by small molecular drug generates anxiolytic effect. To date, however, the function of nNOS in affective disorders is not well reviewed. Here, we summarize works about nNOS and its signal mechanisms implicated in the pathophysiology of affective disorders. On the basis of this review, it is suggested that future research should more fully focus on the role of nNOS in the pathomechanism and treatment of affective disorders.

Immunocytochemical Localization of Choline Acetyltransferase in the Microbat Visual Cortex

The purpose of the present study was to investigate the organization of choline acetyltransferase (ChAT)-immunoreactive (IR) fibers in the visual cortex of the microbat, using standard immunocytochemistry and confocal microscopy. ChAT-IR fibers were distributed throughout all layers of the visual cortex, with the highest density in layer III and the lowest density in layer I. However, no ChAT-IR cells were found in the microbat visual cortex. ChAT-IR fibers were classified into two types: small and large varicose fibers. Previously identified sources of cholinergic fibers in the mammalian visual cortex, the nucleus of the diagonal band, the substantia innominata, and the nucleus basalis magnocellularis, all contained strongly labeled ChAT-IR cells in the microbat. The average diameter of ChAT-IR cells in the nucleus of the diagonal band, the substantia innominata, and the nucleus basalis magnocellularis was 16.12 μm, 13.37 μm, and 13.90 μm, respectively. Our double-labeling study with ChAT and gamma-aminobutyric acid (GABA), and triple labeling with ChAT, GABA, and post synaptic density 95 (PSD-95), suggest that some ChAT-IR fibers make contact with GABAergic cells in the microbat visual cortex. Our results should provide a better understanding of the nocturnal bat visual system.