A Histomorphometric Study on the Neurohypophysis of STZ-induced Diabetic Albino Rats

AIM: To assess the hyperglycemia-induced microscopic changes in the posterior pituitary of streptozotocin (STZ) - induced diabetic adult albino rats. MATERIAL AND METHODS: After clearance from the Institutional Animal Ethical Committee, 36 animals were divided into six groups having six rats each: control, two weeks, one month, two months, four months and six months. Diabetes was induced with a single dose of streptozotocin administered through intraperitoneal route (60 mg/kg). Body weight and blood sugar were monitored at the biweekly interval. 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. Tissues were fixed in Karnovsky fixative and processed for paraffin sectioning. Routine and special stained sections were studied under the light microscope and relevant findings were recorded. RESULTS: Data obtained from biochemical analyses and histomorphometry along with the histopathological features revealed that with increasing duration of hyperglycemia was associated with increased serum creatinine and reduction in serum total protein; increased mean percentage of darkly stained large sized pituicytes and notable thickening of perisinusoidal collagen. CONCLUSION: It is therefore concluded that long-standing hyperglycemia which is associated with increased occurrence of predominantly large and darkly stained pituicytes and remarkably increased deposition of perisinusoidal collagen appear to be the important contributing factors somehow responsible for the derangement of the function of the posterior pituitary in chronic diabetes.