title: Biphasic cytoarchitecture and functional changes in the BBB induced by chronic inflammatory pain.
abstract: The blood-brain barrier (BBB) is a dynamic system which maintains brain homeostasis and limits CNS penetration via interactions of transmembrane and intracellular proteins. Inflammatory pain (IP) is a condition underlying several diseases with known BBB perturbations, including stroke, Parkinson's, multiple sclerosis and Alzheimer's. Exploring the underlying pathology of chronic IP, we demonstrated alterations in BBB paracellular permeability with correlating changes in tight junction (TJ) proteins: occludin and claudin-5. The present study examines the IP-induced molecular changes leading to a loss in functional BBB integrity. IP was induced by injection of Complete Freund's Adjuvant (CFA) into the plantar surface of the right hindpaw of female Sprague-Dawley rats. Inflammation and hyperalgesia were confirmed, and BBB paracellular permeability was assessed by in situ brain perfusion of [14C]sucrose (paracellular diffusion marker). The permeability of the BBB was significantly increased at 24 and 72 h post-CFA. Analysis of the TJ proteins, which control the paracellular pathway, demonstrated decreased claudin-5 expression at 24 h, and an increase at 48 and 72 h post-injection. Occludin expression was significantly decreased 72 h post-CFA. Expression of junction adhesion molecule-1 (JAM-1) increased 48 h and decreased by 72 h post-CFA. Confocal microscopy demonstrated continuous expression of both occludin and JAM-1, each co-localizing with ZO-1. The increased claudin-5 expression was not limited to the junction. These results provide evidence that chronic IP causes dramatic alterations in specific cytoarchitectural proteins and demonstrate alterations in molecular properties during CFA, resulting in significant changes in BBB paracellular permeability.
authors.affiliation: Department of Medical Pharmacology, University of Arizona College of Medicine, 1501 N. Campbell Avenue Tucson, AZ 85724-5050, USA.
authors.forename: Tracy A
authors.initials: TA
authors.lastname: Brooks
authors.forename: Scott M
authors.initials: SM
authors.lastname: Ocheltree
authors.forename: Melissa J
authors.initials: MJ
authors.lastname: Seelbach
authors.forename: Rachael A
authors.initials: RA
authors.lastname: Charles
authors.forename: Nicole
authors.initials: N
authors.lastname: Nametz
authors.forename: Richard D
authors.initials: RD
authors.lastname: Egleton
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Davis
mesh_terms: D000818:Animals; D001812:Blood-Brain Barrier / Q000473:pathology* / Q000503:physiopathology*; D002199:Capillary Permeability / Q000502:physiology; D002247:Carbon Isotopes / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology; D002908:Chronic Disease; D004195:Disease Models, Animal; D004487:Edema / Q000139:chemically induced / Q000473:pathology / Q000503:physiopathology; D005260:Female; D005620:Freund's Adjuvant; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D007249:Inflammation / Q000139:chemically induced / Q000150:complications; D007962:Leukocytes / Q000473:pathology / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism; D018613:Microscopy, Confocal / Q000379:methods; D062793:Occludin; D010146:Pain / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology; D010750:Phosphoproteins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013395:Sucrose / Q000378:metabolism; D013997:Time Factors; D062826:Zonula Occludens-1 Protein
chemical_list: D002247:Carbon Isotopes; D015815:Cell Adhesion Molecules; D008565:Membrane Proteins; D062793:Occludin; C568987:Ocln protein, rat; D010750:Phosphoproteins; C569044:Tjp1 protein, rat; D062826:Zonula Occludens-1 Protein; D013395:Sucrose; D005620:Freund's Adjuvant