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We present the clinical course and EEG evolution of an extreme low birth weight preterm neonate with an uncommon type of glycine encephalopathy. The patient presented with myoclonic jerks, apnea and encephalopathy three months after birth without satisfactory therapeutic response. During the first days of clinical symptoms the patient presented a paroxystic burst-attenuation EEG pattern which progressively evolved into an established typical burst-suppression pattern within a few days. West syndrome occurred four weeks later and the patient died at seven months of extra-uterine life due to a serious respiratory infection with cardio-respiratory arrest. Genetic analysis showed a non-previously described mutation affecting a consensus splice site (IVS2-1G > C 3) in the AMT gene encoding the T protein of the glycine cleavage system.

Aims: The biological mechanisms of epilepsy allow pathophysiological patterns to be established which are essential for the selection of new therapeutic targets. The identification of these mechanisms also provides us with knowledge about the dynamics of neuronal arrangement, synaptogenesis, synaptic transmission and the receptors involved, and even the development of the brain., Development: Recent advances in neurobiology regarding the GABAergic system point to it as playing a leading role in the pathophysiology of epilepsy. We evaluate the different functional formats of the ionotropic (GABAA) and metabotropic (GABAB) gamma-aminobutyric (GABA) receptors. Although the main function posited is inhibitory, owing to the variability of their location, subunits and neuronal physiology/maturation they can even end up expressing excitatory functions. We discuss the anomalies in the GABAergic system identified in animal models with epilepsy and in brain tissue samples from patients submitted to surgery due to epilepsy. The mechanism inhibiting the activation of GABA receptors is performed by hyperpolarisation achieved by entry of Cl- into the neuron--a process mediated by the cotransporter KCC2, typically expressed in the neuron. Mutations in the KCC2 gene produce mice that are susceptible to seizures. In some animal models it has been found that loop diuretics (furosemide) suppress seizures. Mutations in genes that code for ion channels have been identified in numerous epileptic syndromes and this pushes epilepsy ever further inside the broad group of disorders known as channelopathies. The origin could be polygenetic in many cases., Conclusions: The GABAergic system seems to situate itself as the main system implicated in the pathophysiology of epilepsy, although conditions that have been considered to be idiopathic up till now could have a polygenic nature.

A large set of voltage-gated potassium channels is involved in regulating essential aspects of neuronal function in the central nervous system, thus contributing to the ability of neurons to respond to a given input. In the present study, we used immunocytochemical methods to elucidate the regional, cellular and subcellular distribution of the voltage-gated potassium channel subunit Kv1.4, a member of the Shaker subfamily, in the brain. At the light microscopic level, the Kv1.4 subunit showed a unique distribution pattern, being localized in specific neuronal populations of the rat brain. The neuronal regions expressing the highest levels of Kv1.4 protein included the cerebral cortex, the hippocampus, the posterolateral and posteromedial ventral thalamic nuclei, the dorsolateral and medial geniculate nuclei, the substantia nigra and the dorsal cochlear nucleus. The Kv1.4 subunit was also present in other neuronal populations, with different levels of Kv1.4 immunoreactivity. In all immunolabeled regions, the Kv1.4 subunit was mostly diffusely distributed and, to a lesser extent, it stained cell bodies and proximal dendrites. Furthermore, Kv1.4 immunoreactivity was also detected in nerve terminals and axonal terminal fields. At the electron microscopic level, Kv1.4 was located postsynaptically in dendritic spines and shafts at extrasynaptic sites, as well as presynaptically in axon and active zone of axon terminals, in the neocortex and hippocampus. The findings indicate that Kv1.4 channels are widely distributed in the rat brain and suggest that activation of this channel would have different modulatory effects on neuronal excitability.

The effects of a daily injection of the opioid antagonist naltrexone (NALTX, 1 mg/kg SC), from birth to weaning day, on several behavioral parameters were investigated in adult rats of both genders. This work uses three behavioral tests. The use of the open-field test in addition to the holeboard and plus-maze tests allows the measurement of complementary parameters, and provided further information on diverse components of behavior. The effect of repeated testing (habituation) over 3 consecutive days of open-field testing was also assessed. In accordance with previous reports, female rats showed higher locomotor activity and exploration and a lower level of emotionality than their male counterparts. The response of the animals to repeated testing seemed to be both sex and treatment dependent. In both males and females, NALTX treatment during the preweanling period did not affect locomotor activity, but increased the animals' levels of anxiety and emotionality and decreased exploratory behavior. Our results indicate that neonatal opioids may play an important role in the development of behavioral responses in the adult.