Comparison of gap junction expression in the adrenal gland.

The presence of alpha 1 (Cx43) gap junction protein was demonstrated in rat, mouse, guinea pig, and bovine adrenal glands with immunocytochemical techniques. The presence of six other connexin species was not detected in the adrenal glands studied. The gap junction stain within the adrenal cortex was punctate and located at sites of cell-cell contact. While little gap junction, alpha 1, staining was detected at sites of cell contact in the zona glomerulosa (ZG), the zona fasciculata (ZF) and zona reticularis (ZR) had intense staining at cell contacts in all rodent species studies. In the bovine adrenal, ZG cells were connected by large gap junctions as were the cells of the ZF and ZR. The variations in alpha 1 distribution within the adrenal cortex may correspond with the different division rates and hormone functions within the adrenal gland as well as species differences between rodent and bovine adrenal gland.

Characterization of gap junction expression in the adrenal gland.

To characterize the presence of gap junctions in adrenal tissue we used immunohistochemical analysis of connexin expression in whole adrenal glands and in primary rat adrenal cortical cell cultures. alpha 1 (connexin 43) gap junction protein was demonstrated in rat adrenal glands and in primary adrenal cell cultures. The alpha 1 gap junction proteins were present in different amounts such that little or no alpha 1 antigen was detected in the zona glomerulosa (ZG), while cells of the zona fasciculata (ZF) and zona reticularis (ZR) stained intensely. There was an inverse relationship between cell division rate and gap junction number in the intact adrenal gland. We placed the cells from the most intensely staining areas (ZF/ZR) of the rat adrenal cortex into culture. These primary adrenal cells expressed alpha 1 gap junction antigen on their cell surfaces in regions of cell-cell contact. ACTH (40mU/ml) treatment resulted in an increase in gap junction expression relative to controls in primary rat adrenal cultures. These results indicate that the abundance of gap junction expression is differential in the cortical zones and can be modulated by hormonal stimulation. These observations are also thought to reflect morphological and functional differences in adrenal cortical zones.