Ontogeny of connexin 32 and 43 expression in the cerebral cortices of ovine fetuses, newborns, and adults

• Published in: Brain research Vol. 1255; pp. 51 - 56
• Main Authors: Sadowska, Grazyna B, Stopa, Edward G, Stonestreet, Barbara S
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 19-02-2009
• Subjects: Age Factors; Animals; Animals, Newborn - growth & development; Animals, Newborn - metabolism; Blotting, Western; Brain; Cerebral Cortex - metabolism; Connexin; Connexin 43 - metabolism; Connexins - metabolism; Development; Female; Fetus - metabolism; Gap junction; Gap Junction beta-1 Protein; Gap Junctions - metabolism; Gestation; Gestational Age; Maturation; Neurology; Pregnancy; Sheep; Sheep - embryology; Sheep - metabolism; Brain; Connexin; Maturation; Development; Sheep; Gestation; Gap junction
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2008.12.004

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.