Dynamics of astrocyte adhesion as analyzed by a combination of atomic force microscopy and immunocytochemistry: the involvement of actin filaments and connexin 43 in the early stage of adhesion

We observed the time-dependent morphological alteration of astrocytes durin g their adhesion by atomic force microscopy (AFM) and investigated the rela tionships between this morphological alteration and the localization of act in filaments and connexin 43 by immunocytochemistry. The fine processes obs erved as fine ridge-like structures by AFM were closely concerned with ac t in filaments by immunocytochemistry, During the adhesion of astrocytes, act in filaments appeared to be aligned regularly beyond the borders among diff erent cells. Detectable connexin immunoreactivity was changed in the follow ing regions: 1) the tips of fine cell processes and the cell margin when as trocytes started to adhere; 2) the border of cells when astrocytes tightly adhered; and 3) non-specific sites when astrocytes became a cluster. In the former two cases, the immunopositive spots for connexin were observed to c olocalize with the tips of cell processes with actin filaments. These resul ts strongly suggest that connexin associated with actin filaments at the ti p of cell processes plays an important role in the early stage of the adhes ion of astrocytes. These observations afford valuable clues for understandi ng the glial communication.