Endocrine Abstracts

Connexins are a proteins critically involved in the formation of gap junction, which connect cells with each other and enable the exchange of small compounds and, besides having a role independently of gap junction formation. At least, in the anterior pituitary two cellular networks have already been identified, one of them is composed of the endocrine inactive folliculo-stellate cells and the second one is the GH-producing somatotroph cell network. It is supposed that gap junctions may play an important role in these networks. The network organization of endocrine and non-endocrine cells of the anterior pituitary may be of high functional relevance and may allow a more rapid and coordinated release of hormones and/or growth factors. Loss of these network structures during non-coordinated pituitary adenoma cell growth may play a role in the formation of pituitary tumors, as it has already been reported from other forms of solid tumors, in which disturbed connexins expression has been observing. The aim of this work is to determined mRNA expression of connexin 26, 32 and 43 in normal pituitary and endocrine-inactive adenomas, somatotropinomas and corticotropinomas. We determined mRNA connexin expression using real time reverse transcriptase PCR (qRT-PCR) in series of pituitary tumors. Our initial results demonstrated a decrease in connexins expression in most of adenomas studied. We observed a decrease an expression in connexin 26 in 12 tumors of 14 non-functioning adenomas, in six tumours of seven corticotropinomas and in four tumours of four somatotropinomas when compared it with normal pituitary connexin 26, 32 and 43 expression. We analyzed connexin 32 mRNA expression in these adenomas the data showed that a decrease in connexin it expression in ten adenomas of 13 non-functioning adenomas, in five adenomas of five corticotropinomas and in five adenomas of five somatotropinomas. Finally, we also observed a decrease in connexin 43 mRNA expression in 12 adenomas of 14 non-functioning adenomas, in three adenomas of five corticotropinomas and in five adenomas of five somatotropinomas. Taken together, these data raise questions about the possibility of connexins are participating in the tumorigenesis and/or the pathophysiology of pituitary adenomas.