A Histomorphological Study on the Olfactory Bulb of Diabetic Albino Rats

摘要

Long standing hyperglycemia is generally associated with a decline in the chemical senses including smell due to its unfavorable destructive effects on the small sized neurons of the Olfactory bulb (OB). Accordingly, the current study was aimed to analyze the effect of experimental hyperglycemia on OB of albino rats. To detect a possible change on the olfactory bulb during hyperglycemia, 36 albino rats were divided into six groups of six rats each and were designated as control, two week, one month, two month, four month and six month respectively. Diabetes was induced with single dose of streptozotocin (STZ-60 mg/kg, IP). The inductions of diabetes were confirmed by measuring the blood glucose levels in the tail blood with a Glucometer. At the end of each experimental period animals were euthanized by deep ether anesthesia and blood samples were collected by direct puncture of heart for biochemical analysis. Animals were perfused with Karnovsky fixative. After two days tissue specimen were collected and processed for light microscopic studies. Biochemical analysis of serum revealed increased serum creatinine and reduced serum total protein. Histopathology and histomorphometry of OB revealed that the progressively increasing duration of hyperglycemia was associated with noticeable decreased diameter of OB glomeruli, decrease diameter of mitral cells and thickening of supporting connective tissue around the OB and blood vessels. It is concluded that the association of the long-standing hyperglycemia with frequent occurrence of hypercellular glomeruli and misplaced mitral cells, decreased diameter of OB glomeruli and mitral cells, subtle laminar disarray and added deposition of collagen fibers around OB and blood vessels appear to be important contributing factors responsible for the derangement of olfactory function in diabetics.