Long term complications of diabetes are reduced in patients with tightly controlled plasma glucose levels. A frequent consequence of this tight control is severe hypoglycemia. Recurrent hypoglycemia leads to hypoglycemia-associated autonomic failure and unawareness, through mechanisms that are not well understood at this time. This proposal describes a rodent model of reduced sympathoadrenal activation after hypoglycemia. Brain changes observed in this model include evidence of neuronal apoptosis and changes in peptide gene expression in the arcuate nucleus of the hypothalamus. The experiments proposed here investigate the role of the arcuate nucleus in responses to hypoglycemia. Phenotyping arcuate neurons activated by hypoglycemia will be done by combining Fos immunohistochemistry with in situ hybridization for neuropeptide Y, pro-opiomelanocortin, glutamic acid decarboxylase and glucokinase. The role of brain hypoglycemia in endocrine and Fos responses to hypoglycemia will be assessed using systemic insulin combined with brain glucose infusions. Recovery of normal counter regulation and arcuate gene expression after hypoglycemia will be evaluated using physiological measures, in situ hybridization, Northern blots, and RT-PCR. The results of this research will provide fundamental information about the neuroanatomy of the counterregulatory response and the brain alterations after recurrent hypoglycemia that dangerously reduce the organism' s ability to respond to this important biological signal. The principle investigator is a master's prepared nurse with doctoral training in physiology, postdoctoral training in neuroendocrinology, and independent research experience investigating the functional neuroanatomy of brain responses to peripheral immune stimulation. She now seeks to broaden her research focus to study central nervous system integration of responses to hypoglycemia, a growing problem in patients with intensive treatment of type I diabetes mellitus. Since long-term changes in responsiveness to hypoglycemia are likely to involve changes in gene expression, the Principal Investigator seeks mentored development of her research skills in the area of molecular neurobiology. The University of Pennsylvania School of Nursing is a top-ranked academic nursing center, and is highly ranked in quantity and quality of its sponsored research programs. The University of Pennsylvania has a nationally funded Diabetes Endocrinology Research Center, and an active Institute of Neurological Sciences. The research plan, candidate, and environment are well-suited for an ongoing career in fundamental diabetes research.
| Tkacs, Nancy C; Pan, Yanhua; Sawhney, Gagan et al. (2007) Hypoglycemia activates arousal-related neurons and increases wake time in adult rats. Physiol Behav 91:240-9 |
| Tkacs, Nancy C; Thompson, Hilaire J (2006) From bedside to bench and back again: research issues in animal models of human disease. Biol Res Nurs 8:78-88 |
| Tkacs, Nancy C; Pan, Yanhua; Raghupathi, Ramesh et al. (2005) Cortical Fluoro-Jade staining and blunted adrenomedullary response to hypoglycemia after noncoma hypoglycemia in rats. J Cereb Blood Flow Metab 25:1645-55 |
| Marin-Spiotta, Alejandro; Levin, Barry E; Tkacs, Nancy C (2004) A single episode of central glucoprivation reduces the adrenomedullary response to subsequent hypoglycemia in rats. Neurosci Lett 360:81-4 |
