title: c-fos gene expression is increased in the paraventricular hypothalamic nucleus of Sprague-Dawley rats with visceral pain induced by acetic acid without detectable changes of corticotrophin-releasing factor mRNA: a quantitative approach with an image analysis system.
abstract: This study is the first of its kind to demonstrate that c-Fos immunoreactivity (ir) together with c-fos mRNA in their immediately adjacent tissue sections of a discrete brain region can be reliably measured. The c-fos gene expression in the paraventricular hypothalamic nucleus (PVN) of Sprague-Dawley rats for an animal model for visceral or somatovisceral pain induced by 2% acetic acid (AA) was used in this study. Specifically, c-fos mRNA signals were measured by quantitative autoradiography after in situ hybridization using c-fos oligodeoxynucleotide probe, and c-Fos-ir signals were represented by c-Fos immunostaining, as detected using c-Fos antibody in a regular immunohistochemistry. Signals from both c-Fos-ir and c-fos mRNA in the PVN were measured from their immediately adjacent cryostat sections. For the measurement of c-Fos-ir, it was carried out by reading 10 rectangles (1,000 microm(2)/rectangle) on each PVN section with c-Fos immunostaining. Specific signals were obtained from subtracting the nonspecific background signal from the total signals using a computer-assisted image analysis system. Results indicated that the AA treatment induced a significant increase of both c-Fos-ir and c-fos mRNA in the PVN. Interestingly, there was no increase of corticotrophin-releasing factor (CRF) mRNA expression in the PVN and central nucleus of the amygdala of Sprague-Dawley rats subjected to the AA treatment. In summary, this study has demonstrated that c-Fos-ir in the PVN with an anatomical resolution can be semiquantitatively measured after immunohistochemistry using an image analysis system, and that increased c-fos mRNA in the PVN 1 hr after the AA treatment is associated with no changes of the CRF mRNA expression.
authors.affiliation: Department of Anatomy and Cell Biology, School of Medicine, Indiana University, Indianapolis, Indiana 46202, USA. bhwang@iupui.edu
authors.forename: Bang H
authors.initials: BH
authors.lastname: Hwang
authors.forename: Hung-Ming
authors.initials: HM
authors.lastname: Chang
authors.forename: Zhu-Hua
authors.initials: ZH
authors.lastname: Gu
authors.forename: Ryoji
authors.initials: R
authors.lastname: Suzuki
mesh_terms: D015746:Abdominal Pain / Q000378:metabolism*; D019342:Acetic Acid; D000818:Animals; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism*; D015870:Gene Expression; D016762:Genes, fos; D007091:Image Processing, Computer-Assisted; D007274:Injections, Intraperitoneal; D008297:Male; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D003346:Corticotropin-Releasing Hormone; D019342:Acetic Acid