To increase our knowledge of the role of peptide hormone stimulation in gap junction
protein expression and adrenal cortical cell function, primary rat adrenal cortical
cells were treated with adrenocorticotropin, and gap junction proteins were measured.
Immunocytochemistry and western blot analysis were used to detect and characterize
gap junction type and distribution. The gap junction protein, connexin 43 (alpha 1),
was detected. Analysis of six connexin protein types did not reveal gap junction species
other than alpha 1. Cells of the inner adrenal cortical zones, zonae fasciculata and
reticularis, were demonstrated to have the highest number of gap junctions per cell
in the adrenal gland. Adrenal cell cultures enriched for the two inner cortical adrenal
zones were established and demonstrated also to express alpha 1 gap junction protein.
Adrenocorticotropin (40 mUnits/ml) and dibutyryl cyclic adenosine monophosphate (1
mM) treatments increased alpha 1 gap junction protein levels and decreased cell proliferation
rates in the cell cultures. The results are consistent with the hypothesis that gap
junction expression can be regulated by adrenocorticotropin acting through the second
messenger cyclic adenosine monophosphate. It can be suggested that gap junction expression
in the adrenal gland may be under hormonal influence, and that gap junctions serve
as passage for movement of molecules involved in control of cell proliferation. Supported
by NSF grant #MCB-9514285.
Key words
Gap Junction Proteins - Adrenal Gland - Adrenal Cells - Connexin
