Hypophysectomy results in a loss of connexin gap junction protein from theadrenal cortex

To test the hypothesis that gap junctions are dependent on the tropic state of the adrenal gland, the effect of hypophysectomy on connexin 43 (alpha ( 1)- Cx43) gap junction protein occurrence and distribution was examined in mice. Gap junction protein occurrence was assessed with immunohistochemical techniques. In the adrenal gland from intact animals, alpha (1)- Cx43 gap junction protein was detected in the zonae fasciculata(ZF) and reticularis (ZR) while only a few alpha (1)- Cx43 gap junction plaques were found conne cting zona glomerulosa(ZG) cells. Hypophysectomy led to a profound atrophy of the cortex which was more marked in the inner zones (zonae fasciculata a nd reticularis) than in the zona glomerulosa. There was a time dependent lo ss of alpha (1)- Cx43 gap junction protein in the adrenal cortex after hypo physectomy. At 33 day following hypophysectomy there was a two fold decreas e in gap junctions in the zona fasciculata while the average gap junction p laque size was not different than the size seen in control animal adrenal g lands.. ACTH (1U/gm body weight) treatment in hypophysectomized animals inc reased the number of gap junction plaques in the zona fasciculata. Hypophys ectomy led to diminished alpha (1)-Cx43 gap junction expression in the zona fasciculata which could be restored by ACTH treatment. Because altering th e tropic state of the adrenal glands via hypophysectomy leads to a reductio n in gap junction number, it can be suggested that control of gap junction expression in the adrenal gland is hormone dependent and linked to adrenal gland function.