title: Ontogeny of connexin 32 and 43 expression in the cerebral cortices of ovine fetuses, newborns, and adults.
abstract: Gap junctions are specialized membrane structures that mediate intercellular communication and facilitate passage of ions and small molecules between adjacent cells. Connexins comprise a multigene family of transmembrane proteins that form gap junctions. Connexin-32 and connexin-43 are among the most abundant connexins in brain and are highly expressed during development. Connexin-32 is expressed primarily in oligodendrocytes and connexin-43 in astrocytes in adult brain. However, both connexins are expressed in neurons during development. We examined the effects of ontogeny on connexin-32 and connexin-43 protein abundance in cerebral cortices of sheep during development. Western immunoblot was used to measure connexin-32 and connexin-43 expression in cerebral cortices of fetuses at 60%, 80%, and 90% of gestation, in newborn lambs and adult sheep. Values were expressed as ratios to a single adult control cerebral cortical sample. Connexin-32 abundance was higher (P<0.05) in cerebral cortices of fetuses at 60% of gestation (3.0+/-0.68, mean+/-SD), than in those at 90% of gestation (1.7+/-0.3), in newborn (1.8+/-0.55), and adult sheep (0.84+/-0.19), respectively. In contrast, connexin-43 abundance was higher (P<0.05) in cerebral cortices of fetuses at 90% of gestation (0.44+/-0.17), newborn (0.69+/-0.12) and adult sheep (1.14+/-0.13), than in those at 60% of gestation (0.05+/-0.01). We conclude that (1) connexin-32 and connexin-43 protein are expressed early in fetal life and throughout development, (2) each connexin displays a unique pattern of change with development, (3) connexin-43 exhibited ontogenic increases in protein abundance, whereas, connexin-32 exhibited reciprocal decreases in abundance late in fetal development, in newborn and adult sheep.
authors.affiliation: Department of Pediatrics, Women and Infants' Hospital of Rhode Island, Providence, RI 02905-2499, USA.
authors.forename: Grazyna B
authors.initials: GB
authors.lastname: Sadowska
authors.forename: Edward G
authors.initials: EG
authors.lastname: Stopa
authors.forename: Barbara S
authors.initials: BS
authors.lastname: Stonestreet
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development / Q000378:metabolism; D015153:Blotting, Western; D002540:Cerebral Cortex / Q000378:metabolism*; D018031:Connexin 43 / Q000378:metabolism*; D017630:Connexins / Q000378:metabolism*; D005260:Female; D005333:Fetus / Q000378:metabolism; D017629:Gap Junctions / Q000378:metabolism; D005865:Gestational Age; D011247:Pregnancy; D012756:Sheep / Q000196:embryology* / Q000378:metabolism; D000097002:Gap Junction beta-1 Protein
chemical_list: D018031:Connexin 43; D017630:Connexins; D000097002:Gap Junction beta-1 Protein