Expression of neuronal nitric oxide synthase in the developing superficial layers of the rat superior colliculus

The “Primitive Brain Dysfunction” Theory of Autism: The Superior Colliculus Role

A better understanding of the pathogenesis of autism will help clarify our conception of the complexity of normal brain development. The crucial deficit may lie in the postnatal changes that vision produces in the brainstem nuclei during early life. The superior colliculus is the primary brainstem visual center. Although difficult to examine in humans with present techniques, it is known to support behaviors essential for every vertebrate to survive, such as the ability to pay attention to relevant stimuli and to produce automatic motor responses based on sensory input. From birth to death, it acts as a brain sentinel that influences basic aspects of our behavior. It is the main brainstem hub that lies between the environment and the rest of the higher neural system, making continuous, implicit decisions about where to direct our attention. The conserved cortex-like organization of the superior colliculus in all vertebrates allows the early appearance of primitive emotionally-related behaviors essential for survival. It contains first-line specialized neurons enabling the detection and tracking of faces and movements from birth. During development, it also sends the appropriate impulses to help shape brain areas necessary for social-communicative abilities. These abilities require the analysis of numerous variables, such as the simultaneous evaluation of incoming information sustained by separate brain networks (visual, auditory and sensory-motor, social, emotional, etc.), and predictive capabilities which compare present events to previous experiences and possible responses. These critical aspects of decision-making allow us to evaluate the impact that our response or behavior may provoke in others. The purpose of this review is to show that several enigmas about the complexity of autism might be explained by disruptions of collicular and brainstem functions. The results of two separate lines of investigation: 1. the cognitive, etiologic, and pathogenic aspects of autism on one hand, and two. the functional anatomy of the colliculus on the other, are considered in order to bridge the gap between basic brain science and clinical studies and to promote future research in this unexplored area.

Systematically Characterize the Anti-Alzheimer's Disease Mechanism of Lignans from S. chinensis based on In-Vivo Ingredient Analysis and Target-Network Pharmacology Strategy by UHPLC⁻Q-TOF-MS

Lignans from Schisandra chinensis (Turcz.) Baill can ameliorate cognitive impairment in animals with Alzheimer’s disease (AD). However, the metabolism of absorbed ingredients and the potential targets of the lignans from S. chinensis in animals with AD have not been systematically investigated. Therefore, for the first time, we performed an in-vivo ingredient analysis and implemented a target-network pharmacology strategy to assess the effects of lignans from S. chinensis in rats with AD. Ten absorbed prototype constituents and 39 metabolites were identified or tentatively characterized in the plasma of dosed rats with AD using ultra high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. Based on the results of analysis of the effective constituents in vivo, the potential therapeutic mechanism of the effective constituents in the rats with AD was investigated using a target-network pharmacology approach and independent experimental validation. The results showed that the treatment effects of lignans from S. chinensis on cognitive impairment might involve the regulation of amyloid precursor protein metabolism, neurofibrillary tangles, neurotransmitter metabolism, inflammatory response, and antioxidant system. Overall, we identified the effective components of lignans in S. chinensis that can improve the cognitive impairment induced by AD and proposed potential therapeutic metabolic pathways. The results might serve as the basis for a fundamental strategy to explore effective therapeutic drugs to treat AD.

Role of nitric oxide and related molecules in schizophrenia pathogenesis: biochemical, genetic and clinical aspects

Currently, schizophrenia is considered a multifactorial disease. Over the past 50 years, many investigators have considered the role of toxic free radicals in the etiology of schizophrenia. This is an area of active research which is still evolving. Here, we review the recent data and current concepts on the roles of nitric oxide (NO) and related molecules in the pathogenesis of schizophrenia. NO is involved in storage, uptake and release of mediators and neurotransmitters, including glutamate, acetylcholine, noradrenaline, GABA, taurine and glycine. In addition, NO diffuses across cell membranes and activates its own extrasynaptic receptors. Further, NO is involved in peroxidation and reactive oxidative stress. Investigations reveal significant disturbances in NO levels in the brain structures (cerebellum, hypothalamus, hippocampus, striatum) and fluids of subjects with schizophrenia. Given the roles of NO in central nervous system development, these changes may result in neurodevelopmental changes associated with schizophrenia. We describe here the recent literature on NOS gene polymorphisms on schizophrenia, which all point to consistent results. We also discuss how NO may be a new target for the therapy of mental disorders. Currently there have been 2 randomized double-blind placebo-controlled trials of L-lysine as an NOS inhibitor in the CNS.

Determination of dimethylarginine levels in rats using HILIC-MS/MS: an in vivo microdialysis study

Nitric oxide (NO) is one of the most important mediators and neurotransmitters and its levels change under pathological conditions. NO production may be regulated by endogenous nitric oxide synthase (NOS) inhibitors, in particular asymmetric dimethylarginine (ADMA). Most of the interest is focused on ADMA, since this compound is present in plasma and urine and accumulation of ADMA has been described in many disease states but little is known about cerebrospinal fluid (CSF) concentrations of this compound and of its structural isomer symmetric dimethylarginine (SDMA). To determine the levels of methylarginines, we here present a new hydrophilic interaction chromatography (HILIC)-MS/MS method for the precise determination of these substances in CSF from microdialysis samples of rat prefrontal cortex (PFC). The method requires only minimal sample preparation and features isotope-labelled internal standards.

Differential regulation of the neuronal isoform of nitric oxide synthase in the superior colliculus and dorsal lateral geniculate nucleus of the adult rat brain following eye enucleation

Nitric oxide has been shown to play various physiological and pathological roles in the visual system. We studied here the expression of the neuronal isoform of nitric oxide synthase in the rat superior colliculus and in the dorsal lateral geniculate nucleus after unilateral enucleation, by means of immunohistochemistry, immunoblotting, and real-time PCR. Immunohistochemistry revealed an increase of nitric oxide synthase-positive neurons in specific layers of the superior colliculus and in the dorsal lateral geniculate nucleus between 1 and 30 days post-lesion. Immunoblotting analyses confirmed that the neuronal isoform of nitric oxide synthase is upregulated in the superior colliculus and in the dorsal lateral geniculate nucleus after retinal removal. Diaminofluorescein histochemistry suggested that nitric oxide production was increased in both deafferented retinorecipient areas. Our real-time PCR results indicated that nitric oxide synthase transcript levels in the superior colliculus were not significantly altered after monocular enucleation, although an upregulation of the enzyme transcription was detected into the deafferented dorsal lateral geniculate nucleus. These findings indicated that neuronal nitric oxide synthase may undergo different forms of regulation in the adult deafferented visual system.

Changes in nNOS and NADPH diaphorase in frog retina and tectum after axotomy and FGF-2 application

We have shown previously that application of fibroblast growth factor-2 (FGF-2) to the cut optic nerve of the frog, Rana pipiens, augments the survival of retinal ganglion cells (RGCs). In this study, we examine the effects of axotomy and FGF-2 treatment upon the distribution of nitric oxide synthase (NOS) and NADPH diaphorase (NADPH-d) activity in the frog retina and tectum. We find that NOS and NADPH-d are largely absent from RGCs but present in amacrine neurons and in retinorecipient tectal layers. Axotomy alone has little effect on NOS expression or diaphorase activity, apart from slightly increasing the levels of expression in a subpopulation of amacrine cells that arborize in the On sublamina of the inner plexiform layer. FGF-2 application to the optic nerve down-regulates NOS expression and activity in the retina and up-regulates it in the tectum, particularly in retinorecipient layers. Electron microscopy of the optic nerve and neurofilament immunostaining of the tectum suggests that FGF-2 treatment increases the number of regenerating retinal axons arriving at the tectum. The effects in the retina and tectum are probably indirect, that in the retina being due to retrograde signaling from RGCs to amacrine neurons, and that in the tectum being due to re-induction of NOS expression in tectal neurons by the arrival of regenerating axons. At this stage, it appears unlikely that these changes in NOS play a role in the FGF-2's survival effect on RGCs.

The many faces of nitric oxide in schizophrenia. A review

Intense research has been conducted in an effort to identify specific biological markers of schizophrenia. The gas nitric oxide (NO) is one of the most important signaling molecules involved in a plethora of cellular events that take place in the cardiovascular, immune and nervous systems of animals. This survey aims to demonstrate that NO and its metabolites play important roles in schizophrenia and have a significant influence on our understanding of the development, progression and treatment of the disease. Special emphasis is given to the impact of NO metabolism on processes known to be disturbed in schizophrenia (i.e., cell migration, formation of synapses, NMDA receptor mediated neurotransmission, membrane pathology and cognitive abilities). However, when comparing data on the NO metabolism in the brain tissue and body fluids of schizophrenics with those obtained from patients with other neurological and psychiatric diseases, it becomes clear that alterations of NO metabolism are not unique to, or indicative of, schizophrenia. Thus, NO and its metabolites are not suitable diagnostic tools to distinguish schizophrenia from psychically healthy control cases or from other brain disorders.