Altered expression of nerve growth factor and its receptors in the kidneys of diabetic rats

Type 1 diabetes (DB) is a multifactorial metabolic disorder characterized by loss of insulin-producing pancreatic ß-cells, and metabolic and functional deficits in a number of cells, including kidney cells. Nerve growth factor (NGF) is a signaling molecule that is up-regulated in cells affected by diabetes-linked disorders. However, whether DB alters the expression of NGF in the kidney is not known.

DB was induced in adult male rats with a single injection of streptozotocin (STZ), and NGF protein levels were analyzed in a time-course study in serum and kidney. The expression of NGF receptors in the kidneys of healthy and DB rats was evaluated by immunohistochemistry. NGF levels as well as apoptotic features in the kidneys of healthy rats injected with purified NGF were also assessed.

This study revealed that DB elevates NGF levels in serum and NGF expression in the kidney and that subcutaneous administration of NGF causes a marked uptake of NGF in kidney cells. The elevated presence of NGF in kidney cells is not associated with proapoptotic factor expression.

The present data suggest that NGF presence in the kidney might play a survival, and most probably protective, role in kidney cells.