Synucleinopathies: Intrinsic and Extrinsic Factors.

α-Synucleinopathies are a group of neurodegenerative disorders characterized by alterations in α-synuclein (α-syn), a protein associated with membrane phospholipids, whose precise function in normal cells is still unknown. These kinds of diseases are caused by multiple factors, but the regulation of the α-syn gene is believed to play a central role in the pathology of these disorders; therefore, the α-syn gene is one of the most studied genes. α-Synucleinopathies are complex disorders that derive from the interaction between genetic and environmental factors. Here, we offer an update on the landscape of the epigenetic regulation of α-syn gene expression that has been linked with α-synucleinopathies. We also delve into the reciprocal influence between epigenetic modifications and other factors related to these disorders, such as posttranslational modifications, microbiota participation, interactions with lipids, neuroinflammation and oxidative stress, to promote α-syn aggregation by acting on the transcription and/or translation of the α-syn gene.

γ-Aminobutyric acid quantification in small volume biological samples through enzymatically induced electrochemiluminescence.

γ-Aminobutyric acid (GABA) is a well-known neurotransmitter that regulates inhibitory neurotransmission in the mammalian central nervous system and participates in several processes outside the brain. A reliable quantification method is needed to determine its role in different physiological and pathological conditions. However, GABA measurements have several challenges because GABA is neither fluorescent nor electroactive, and it is difficult to detect using enzymatic reactions because no oxidases or dehydrogenases have been identified. Several methods have been developed to quantify GABA concentrations based on the instrumentation available, the sensitivity required, and the volume of samples analyzed. Most of these methods use high-performance liquid chromatography (HPLC). Here, we describe a method for quantifying GABA concentrations in small volume samples using enzymatically-induced electrochemiluminescence with the well-known GABAse complex, which produces glutamate for use in a luminescent reaction with glutamate oxidase and luminol in an electrochemiluminescence cell. The luminescence obtained was proportional to the GABA concentrations in the micromolar range (1-1000), with linear r2 values > 0.95. GABA standards were treated with the enzymatic reactors to generate glutamate (Glu), which was measured simultaneously with an HPLC technique, to validate this new procedure. The assay was further used to determine GABA concentrations in hippocampal extracts. This alternative may be used to quantify GABA levels in fluid samples, such as microdialysates, other perfusates and tissue extracts. Thus, the method presented here is a good alternative for monitoring GABA levels with good sensitivity compared with the traditional methods that are still in use.

Evidence of sexual dimorphism in D1 and D2 dopaminergic receptors expression in frontal cortex and striatum of young rats.

D1 and D2 receptors are key mediators of dopaminergic signaling in the brain, and since the manifestations of pathologies related to dopamine are different in female and male patients, it is important to analyze if there are sex-related differences in dopaminergic markers. To contribute to the knowledge in this regard, the objective of this report was to characterize the particular expression level of D1 and D2 dopamine receptors in young male and female rats. Striatum (STR) and frontal cortex (CTX) were obtained from intact 30-days old animals, and the D1 and D2 expression level was analyzed by Western blot. The results show a greater expression of D1, but less of D2, in female CTX compared with males, whereas in STR, both D1 and D2 receptors shows predominance in females. These results support the evidence of dimorphic expression in dopaminergic markers, outside of the sex-related brain nuclei, and suggests an early effect of hormones in establishing long life characteristics in dopaminergic circuits.

Monosodium glutamate neonatal treatment as a seizure and excitotoxic model.

Monosodium glutamate (MSG) subcutaneously administrated to neonatal rats induces several neurochemical alterations in the brain, which have been associated with an excitotoxic process triggered by an over activation of glutamate receptors; however there are few systematic studies about initial changes in intracerebroventricular (i.c.v.) Glu levels produced by MSG in the brain. Thus, to characterize these changes, rat pups were injected with a MSG solution at 1, 3, 5 and 7 postnatal days (PD), and i.c.v. Glu levels and hippocampal total content of related amino acids (Asp, Glu, Gln, Gly, Tau, Ala and GABA) were estimated before, immediately and after each injection. Behavioral and EEG responses were also monitored after MSG administrations. Significant rise in i.c.v. Glu levels were found, mainly in response to the first and second injection. Moreover, the total content of all amino acids evaluated also increased during the first hour after the first MSG administration but only Glu and GABA remained elevated after 24 h. These biochemical modifications were accompanied with behavioral alterations characterized by: screeching, tail stiffness, head nodding, emprosthotonic flexion episodes and generalized tonic-clonic convulsions, which were associated with electroencephalographic pattern alterations. Altered behavior found in animals treated with MSG suggests an initial seizure situation. Although four MSG administrations were used, the most relevant findings were observed after the first and second administrations at PD1 and PD3, suggesting that only two MSG injections could be sufficient to resemble a seizure and/or excitotoxic model.

Neonatal monosodium glutamate treatment modifies glutamic acid decarboxylase activity during rat brain postnatal development.

Monosodium glutamate (MSG) produces neurodegeneration in several brain regions when it is administered to neonatal rats. From an early embryonic age to adulthood, GABA neurons appear to have functional glutamatergic receptors, which could convert them in an important target for excitotoxic neurodegeneration. Changes in the activity of the GABA synthesizing enzyme, glutamic acid decarboxylase (GAD), have been shown after different neuronal insults. Therefore, this work evaluates the effect of neonatal MSG treatment on GAD activity and kinetics in the cerebral cortex, striatum, hippocampus and cerebellum of the rat brain during postnatal development. Neonatal MSG treatment decreased GAD activity in the cerebral cortex at 21 and 60 postnatal days (PD), mainly due to a reduction in the enzyme affinity (K(m)). In striatum, the GAD activity and the enzyme maximum velocity (V(max)) were increased at PD 60 after neonatal MSG treatment. Finally, in the hippocampus and cerebellum, the GAD activity and V(max) were increased, but the K(m) was found to be lower in the experimental group. The results could be related to compensatory mechanisms from the surviving GABAergic neurons, and suggest a putative adjustment in the GAD isoform expression throughout the development of the postnatal brain, since this enzyme is regulated by the synaptic activity under physiological and/or pathophysiological conditions.