Histological and ultrastructural changes of the brain, pancreas and ileum of diabetic and nondiabetic mice under heat stress with special reference to heat shock proteins

ABSTRACT

The current study was designed to evaluate the thermal stress effect on brain, pancreas and ileum in normal and alloxan-diabetic mice by studying the structural changes at both light and electron microscopical levels and by studying the molecular changes expressed through the examination of protein banding pattern in the electrophorograms of the different groups . The animals were divided into four main groups; control mice, alloxan diabetic mice, heat-stressed nondiabetic mice and heat-stressed diabetic mice. No remarkable changes could be detected in nonstressed diabetic animals except the ultrastructural changes noticed in B cells of islets of Langerhans in pancreas. The heat-stressed nondiabetic animals displayed various cellular and subcellular changes in the organs of study, which were focal in most of the cases. Signs of restitution were also noted in the three selected organs in this group. On the other hand, heat stress was so much destructive in diabetic mice and that was so clear specially in pancreas. The difference in degree of cellular injury between diabetics and nondiabetics is correlated with data of protein studies which demonstrated more expression of heat stress proteins [HSPs] in nondiabetics and attenuation of this expression in diabetics. These stress proteins are suggested to play an important role in protection against thermal stress injury. Consistent with this, the brain which showed more expression of HSPs was the least affected of the three organs. Moreover, the attenuated expression of these HSPs in diabetics highlights the suggestion that diabetes deranged the stress response and delayed the expression of the protective HSPs. In conclusion further studies are needed to characterize the molecular structure of the HSPs and the genes responsible for the expression of these proteins in these tissues and the other body tissues