Impairment of transneuronal traffic in Streptozotocin-induced diabetes, a WGA-HRP neurohistochemical study in the rat

Abstract

Retrograde transport of Wheat germ agglutinin conjugated to Horseradish peroxidase (WGA-HRP) was used in labeling vagal neurons projecting to the stomach from the dorsal motor nucleus of the vagus nerve (DMNV) in Streptozotocin (STZ)-induced diabetic rats. Diabetes was induced in the experimental rats by intraperitoneal injection of buffered STZ. Control rats were injected with an equivalent volume of the citrate buffer not containing STZ.The experimental rats, which became diabetic about 24 h after intraperitoneal injection of STZ, were kept alive for a period of 24 weeks to attain a chronic state of diabetes. Control euglycaemic rats were also kept alive for 24 weeks. At the end of 24 weeks, the two groups of rats were prepared for stomach surgery. Following anaesthesia laparotomy was performed and the stomach exteriorized. The anterior and posterior walls of the stomach were injected with 0.1 ml of 5% WGA-HRP in 0.5 M sodium chloride. Experimental and control rats were sacrificed 48-72 h after tracer injection by transcardial perfusion with normal saline, fixative and buffered sucrose.Transverse serial frozen sections of the brainstem were processed for WGA-HRP neurohistochemistry and analyzed under light and dark-field microscopy. The analyses of the sections taken from the chronic diabetic rats revealed fewer WGA-HRP labeled neurons in the DMNV than sections taken from the control euglycaemic rats. The depletion of labeled neurons in the diabetic rats compared with the euglycaemic rats is indicative of an interference with the mechanism of retrograde neuronal transport of WGA-HRP by chronic diabetic state.

Impairment of Retrograde Neuronal Transport in Cardiac Vagal Motoneurons in Streptozotocin-Induced Diabetic Rats: A Wheat Ger Agglutinin-Horseradish Peroxidase Neurohistochemical study

“…Since both groups of rats i.e., diabetic and non-diabetic were subjection to the same experimental procedures it appears logical to attribute the difference in the results of the present study to the diabetic state of the experimental rats. The result of the present study is also consistent with earlier reports in which depletion of labeled vagal neurons were observed following tracer injections of vagally innervated organs of diabetic rats [11,31] . The result of the present study is also in agreement with that of Hellweg et al and Lee et al [5] .…”

The vignette for V13N5 Issue

“…Streptozotocininduced diabetes in rats has been shown to alter the neurotrophin content in the cervical vagus nerve [22]. In this issue, based on a decrease in the number of retrogradely labeled neurons within the dorsal motor nucleus of the vagus nerve in Streptozotocin-induced diabetic rats as compared with control euglycaemic rats, it was suggested that the retrograde transport process along the axons of the affected neurons was impaired during chronic diabetes [23]. Although impaired neuronal transport is implicated in the findings of Odekunle [23], further investigation is needed to elucidate whether endogenous neurotrophin is involved in the process.…”