Stress-Associated Molecular and Cellular Hippocampal Mechanisms Common for Epilepsy and Comorbid Depressive Disorders

The review discusses molecular and cellular mechanisms common to the temporal lobe epileptogenesis/epilepsy and depressive disorders. Comorbid temporal lobe epilepsy and depression are associated with dysfunction of the hypothalamic-pituitary-adrenocortical axis. Excessive glucocorticoids disrupt the function and impair the structure of the hippocampus, a brain region key to learning, memory, and emotions. Selective vulnerability of the hippocampus to stress, mediated by the reception of glucocorticoid hormones secreted during stress, is the price of the high functional plasticity and pleiotropy of this limbic structure. Common molecular and cellular mechanisms include the dysfunction of glucocorticoid receptors, neurotransmitters, and neurotrophic factors, development of neuroinflammation, leading to neurodegeneration and loss of hippocampal neurons, as well as disturbances in neurogenesis in the subgranular neurogenic niche and formation of aberrant neural networks. These glucocorticoid-dependent processes underlie altered stress response and the development of chronic stress-induced comorbid pathologies, in particular, temporal lobe epilepsy and depressive disorders.

[Molecular mechanisms of brain peptide-containing drugs: cortexin]

The goal of treatment of brain pathologies may be regarded as re-establishment of optimal brain plasticity. Disturbances in neuroplasticity are associated with the appearance of multiple targets that should be subjects for pharmacological correction. Peptide hydrolysates derived from animal brain became a basis for multi-component organ-specific drugs which are widely used for treatment of cerebral pathologies. Potentially, the presence of many components in such drugs may be beneficial for simultaneous effects on different targets. In this article, new data are analyzed related to relevant molecular mechanisms underlying neuroprotective properties of cortexin. On a model of accelerated aging in rats, cortexin restored the ratio of pro- and antioxidative systems and demonstrated a significant anti-inflammatory effect both in the brain and at the systemic level. In in vitro experiments cortexin effectively and tissue-specifically inhibited brain caspase-8. Neuron-specific proteins β5-tubulin, creatine kinase B and protein 14-3-3 α/β were shown to be molecular partners of cortexin peptides in the brain. Thus, potential molecular mechanisms of cortexin neuroprotective effects are various and associated with key processes underlying neuroplasticity: signal transduction, energy metabolism, proteolytic protein modification, cell structure, as well as neuroinflammation. The pleiotropicity of mechanisms of cortexin action is based on the composition of the drug containing a variety of neuropeptides. The tissue specificity of these mechanisms determines to a significant degree the efficacy of the drug in treatment of cerebral pathologies.

[Cognitive and paroxysmal disorders in the long-term period of traumatic brain injury in children and adolescents]

Traumatic brain injury (TBI) clinical course and outcomes in children have peculiarities as the damage impacts brain, which growth and maturation are continuing. Thus, TBI interferes into normal processes of neuroontogenesis leading to negative consequences on the cognitive functions development, school education, social skills acquisition. Cognitive and behavioral disorders in children and adolescents in the long-term period of TBI become more prominent in co-occurrence with paroxysmal disorders, including posttraumatic headaches, posttraumatic epilepsy and subclinical epileptiform activity on the EEG. Therapeutic and rehabilitation procedures in in the long-term period of TBI in children and adolescents should be conducted not only during the first 12 months after injury, when they are expected to be the most efficient, but also later on taking into consideration continuing processes of the CNS morphological and functional maturation along with the high neuroplasticity of the developing brain.