The aim of the present paper was to check for the presence of cerebrovascular dystroglycan
in vertebrates, because dystroglycan, which is localized in the vascular astroglial
end-feet, has a pivotal function in glio-vascular connections. In mammalian brains,
the immunoreactivity of beta-dystroglycan subunit delineates the vessels. The results
of the present study demonstrate similar patterns in other vertebrates, except for
anurans and the teleost groups Ostariophysi and Euteleostei. In this study, we investigated
1 or 2 representative species of the main groups of Chondrichthyes, teleost and non-teleost
ray-finned fishes, urodeles, anurans, and reptiles. We also investigated 5 mammalian
and 3 bird species. Animals were obtained from breeders or fishermen. The presence
of beta-dystroglycan was investigated immunohistochemically in free-floating sections.
Pre-embedding electron microscopical immunohistochemistry on Heterodontus japonicus
shark brains demonstrated that in Elasmobranchii, beta-dystroglycan is also localized
in the perivascular glial end-feet despite the different construction of their blood-brain
barrier. The results indicated that the cerebrovascular beta-dystroglycan immunoreactivity
disappeared separately in anurans, and in teleosts, in the latter group before its
division to Ostariophysi and Euteleostei. Immunohistochemistry in muscles and western
blots from brain homogenates, however, detected the presence of beta-dystroglycan,
even in anurans and all teleosts. A possible explanation is that in the glial end-feet,
beta-dystroglycan is masked in these animals, or disappeared during adaptation to
the freshwater habitat.
