Poster Presentation The International Congress of Neuroendocrinology 2014

In vivo and real-time monitoring of GFP-expression neuron in the rat hypothalamus via optical fiber (#390)

Norio Iijima 1 , Keisuke Matsumoto 1 , Yoichi Ueta 2 , Hitoshi Ozawa 1
  1. Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
  2. Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
In vivo and real-time monitoring of gene expression in the deep structure of the brain could bring beneficial information for understanding neuroendocrine and autonomic nervous system. We developed a system which could monitor green fluorescent protein (GFP)-expression in the rat brain via optical fiber. One terminal of optical fiber was connected to blue semiconductor laser oscillators/ green fluorescent detector. The other terminal was inserted into the brain and fixed with the cranium. Because the optical fiber is vulnerable to twist caused by animal free moving, we also developed a cage which turns the floor in response to turning of rat’s head for relief of twist-stress of optical fiber between laser oscillator / fluorescent detector and the rat’s head. This system enables real-time monitoring of GFP-expression with awake and unrestrained rat for a week or more. We applied this system to the arginine vasopressin (AVP)-eGFP transgenic rats in which GFP was expressed in the paraventricular nucleus (PVN) and the supraoptic nucleus (SON) in the hypothalamus. These transgenic rats have been reported an increase of GFP-expression in the PVN and the SON under salt-loading condition (Ueta et al. Endocrinology, 2005). Using our real-time monitoring system, we detected an increase of AVP-expression in the hypothalamus via GFP-expression under dehydration. After monitoring via optical fiber, the brain were fixed and cut into slices for observation of the position of fiber-insertion. We also found fluctuation of fluorescent intensity with several hours period. It was considered to be reflected by AVP-expression with the same period. In this study, we show a new monitoring tool of gene expression in the deep structure of brain.