Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA256

Poster Communications

Gene transfer of glyoxalase-1 into the paraventricular nucleus attenuates sympathetic activation and blunt renal dysfunction in diabetic rats

J. Singh1, F. Alomar2, E. A. Adeghate3, K. Patel4, M. Zimmerman4,5, K. R. Bidasee2,5,6

1. School of Forensic Sciences, University of Central Lancashire, Preston, United Kingdom. 2. Department of Pharmacology, University of Dammam, Dammam, Saudi Arabia. 3. Department of Anatomy, United Arab Emirates University, Al Ain, United Arab Emirates. 4. Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, United States. 5. Nebraska Redox Biology Centre, University of Nebraska Medical Center, Lincoln, Nebraska, United States. 6. Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, Nebraska, United States.

Diabetic nephropathy (DN) is a major cause of end-stage renal failure (ESRF) and premature mortality in individuals with chronic Type 1 diabetes mellitus (T1DM). Exaggerated autonomic activity originating in the paraventricular nucleus (PVN) of the hypothalamus is an early step in pathogenesis of DN. Using streptozotocin-induced T1DM rats, we earlier showed that the enhanced autonomic activity in the PVN of T1DM rats arose in part from increased ROS generation, but the underlying reasons for this remain unknown. Recently we discovered supra-physiologic flux of the ROS-generating a-oxoaldehyde methylglyoxal (MG) in brains of T1DM rats. This study, with approval from the Animal Care and Use Committees, UNMC investigated if the increased MG flux is responsible for the enhanced activity of PVN neurons in T1DM rats. After 8 weeks of T1DM, water intake increased 2.2-fold to 550 ml/24 hrs, urine production increased 3-fold to 150 ml/24 hrs, urine norepinephrine increased 2-fold to 7.8 ± 1.2 µg/24 hrs, serum creatinine increased 2.6 fold to 2.3 mg/dL, serum angiotensin II increased by 2.2-fold to 162 pg/ml, and blood urea nitrogen increased 5.3-fold to 100.7 ± 10.3 mg/dl), indicative of DN, polydipsia, and polyuria, n=10 animals. In the PVN of T1DM rats, total ROS increased 2.5 fold, the density of perfused micro-vessels and microvascular leakage assessed using BSA-FITC extravasation were increased 2-fold and reduced 3.2-fold, respectively, activated astrocytes determined from glial fibrillary acidic protein (GFAP) immuno-reactivity was increased 3-fold, TNF-a mRNA was increased 2-fold, and the density of vasopressin-positive neurons in the PVN was reduced 3-fold. Expression of the MG-synthesizing enzyme vascular adhesion protein-1 and MG level were also increased 3-fold in the PVN of T1DM rats. In kidneys of T1DM rats, excessive accumulation of BSA-FITC was prominent in the glomeruli and in the proximal tubules, consistent with hyperfiltration. Microinjection of an adeno-associated containing glyoxalase-I (AAV2/9-Glo-I, 100 nL) into the PVN of rats 1 week after the onset of T1DM, blunted increases in water consumption, urine production, urine norepinephrine, serum creatinine, angiotensin II, and blood urea nitrogen. It also blunted loss of micro-vessel perfusion, micro-vessel leakage, astrocytes activation, total ROS, TNF-a, and attenuated loss of vasopressin-immunoreactivity in PVN neurones. Microinjection of AAV2/9-Glo-I blunted VAP-1 and MG upregulation into the PVN and attenuated BSA-FITC accumulation in the glomeruli and proximal tubules. It is concluded that increased MG flux in the PVN is an underlying cause for increased ROS, sympatho-excitation and nephropathy in T1DM animals, and lowering MG flux in the PVN by overexpression Glo-I was sufficient to attenuate sympatho-excitation and blunt DN.

Where applicable, experiments conform with Society ethical requirements