ABSTRACT
Previous studies have shown that both an intact hypothalamic-pituitary-adrenal axis and prostaglandin E(2) (PGE(2)) are involved in the timing of parturition in sheep. PGE(2) is known to be synthesised by the placenta but has also been found in the foetal brain and pituitary. We propose that the enzymes necessary for production of PGE(2) are found in the ovine foetal pituitary and may be able to exert an autocrine and/or paracrine influence on corticotropes, resulting in an increased secretion of immunoreactive adrenocorticotrophin (irACTH). Pituitary tissues from foetal sheep, of gestational ages 119-126 days, were examined by immunohistochemistry. Primary antibodies for prostaglandin H synthase-1 and -2 (PGHS-1 and PGHS-2), microsomal prostaglandin endoperoxide synthase (mPGES) and irACTH were used to probe expressed proteins and Alexa-Fluor red- and green-fluorescent secondary antibodies were used to visualise the bound primary antibody. Staining for PGHS-1, PGHS-2 and mPGES was found throughout the foetal anterior pituitary. PGHS-1 and mPGES were widely distributed, including but not restricted to corticotropes. PGHS-2 was less widely distributed but occasionally was found in cells adjacent to corticotropes. The results indicate that locally produced prostaglandins may have an influence on the secretion of ACTH, independent of placental PGE(2).
Subject(s)
Adrenocorticotropic Hormone/analysis , Pituitary Gland/chemistry , Pituitary Gland/embryology , Prostaglandin-Endoperoxide Synthases/analysis , Sheep/embryology , Animals , Cyclooxygenase 1 , Cyclooxygenase 2 , Female , Gestational Age , Immunohistochemistry/methods , Isoenzymes/analysis , Microscopy, Fluorescence , PregnancyABSTRACT
Previous studies have shown the immunoregulatory functions IL-4 in type 1 diabetes mellitus. Therefore, the genes involved in the IL-4 regulatory pathway are candidates for diabetes susceptibility genes. Here we have evaluated IL4 and the alpha subunit of the IL-4 receptor (IL4Ralpha) genes using the affected sibpair (ASP) and transmission/disequilibrium test (TDT). We analyzed 309 diabetic families from the United States and 87 families from various European countries. There was no evidence that either of these two genes are linked or associated with type 1 diabetes. Means by which IL-4 directed signals could indirectly alter diabetes susceptibility are proposed.
