A. Sharma, D.F. Muresanu, J.V. Lafuente, A. Nozari, R. Patnaik, A. Ozkizilcik, Z.R. Tian, H. Mössler, H.S. Sharma
Keywords: sleep deprivation in military, emotional stress, brain damage, nanodelivery of cerebrolysin, neuroprptection
Summary:Sleep deprivation (SD) is a serious problem in military personnel during combat operations. Normally they have only a few hours of sleep under severe stressful conditions. This leads to profound mental and cognitive dysfunctions. Previous studies from our laboratory show that 12 to 48 h of SD results in widespread breakdown of the blood-brain barrier (BBB) associated with brain edema and cellular injuries. Since emotional stress is always associated with SD in military, in this investigation we examined a combination of emotional stress and SD on brain pathology and behavioral dysfunction in a rat model. To understand the role of neurotrophic factor in SD and emotional stress we measured regional distribution of brain derived neurotrophic facto (BDNF) in SD. In addition, we used exogenous supplement of Cerebrolysin that is a balanced composition of several neurotrophic factors and active peptide fragments to reduce SD induced brain pathology and behavioral dysfunction. SD was induced in rats using an inverted flowerpot (7 cm diameter) model placed in a pool (30±1°C) where the water level was just below 6 cm from the surface. For emotional stress akin to depression, rats were subjected to 1 h partial immobilization in plastic tube for 2 weeks. Control rats were placed directly on the flowerpot without any prior stress. In these control or experimental rats BBB, brain water and neuronal damages were examined 48 h after SD. Regional brain BDNF levels in cerebral cortex, hippocampus, thalamus, hypothalamus, cerebellum and brain stem were measured using commercial ELISA kit. Our results showed 1 to 2.5-fold exacerbation of BBB breakdown to Evans blue albumin (EBA) and radioiodine (-I) in several brain regions as mentioned above in SD rats subjected to emotional stress as compared to normal rats. The brain water content also showed greater increase in stressed rats after SD. Neuronal injuries were 50 to 90 % higher after SD in stressed animals. On the other hand, BDNF levels showed 60 to 80 % decline in stressed animals after SD. The most marked decrease was seen in hippocampus (normal control 5. 41±0.02 to 2.1±0.08 normal SD; Stress+SD 1.12±0.02 pg/g) and hypothalamus (control 4.23±0.21 to 2.11±0.12 normal SD; Stress+SD 0.84±0.02 pg/g) followed by cortex and cerebellum. Interestingly, cerebrolysin (2.5 ml/kg, i.v.) administration in rats 4 to 6 h after SD in normal rats significantly reduced brain pathology and enhanced regional BDNF levels at 48 h SD, a feature not seen in stressed rats after identical SD. However, when TiO2 nanowired cerebrolysin (2.5 ml/kg, i.v.) was given in identical conditions in SD in stressed rats, markedly reduced BBB breakdown, brain pathology and enhanced the regional BDNF level at 48 h. In these animals, behavioral dysfunctions were also markedly reduced. These observations are the first to show that nanodelivery of cerebrolysin has profound neuroprotective effects in SD following emotions stress, not reported earlier.