Urocortin Expression in Human Pituitary Gland and Pituitary Adenoma

Abstract

Urocortin is a recently identified neuropeptide of the CRF family in the mammalian brain, but its expression in human tissue has been little studied. In this study, we examined urocortin expression in human anterior pituitary gland and pituitary adenomas by RIA, high performance liquid chromatography, immunohistochemistry, messenger ribonucleic acid (mRNA) in situ hybridization, and reverse transcriptase-PCR. Immunoreactive urocortin concentrations in normal pituitary tissue extract were 103.25 +/- 39.05 ng/g wet wt (mean +/- SEM; n = 4), and their levels were all significantly higher than those in other portions of central nervous system of the same subjects. High performance liquid chromatography analysis of human pituitary extract demonstrated a single peak corresponding to that of the expected chromatographic mobility of synthetic human urocortin-(1-40). Urocortin-immunoreactive cells were detected in the anterior pituitary gland. Neither urocortin-immunoreactive nerve fibers nor cells were detected in the posterior lobe. Immunostaining in serial mirror tissue sections revealed that 76.55 +/- 3.06% of urocortin-immunoreactive cells expressed GH immunoreactivity, whereas 22.25 +/- 3.02% and less than 1% of urocortin-immunoreactive cells expressed PRL and ACTH, respectively. mRNA hybridization signals of urocortin were also detected in urocortin-immunopositive pituitary cells. The reverse transcriptase-PCR analysis demonstrated a 145-bp RNA band corresponding to that of the expected length of urocortin in all cases of normal pituitary glands examined (n = 3). We also immunostained urocortin in 52 cases of human anterior pituitary adenomas, including GH-producing adenomas (n = 14), ACTH-producing adenomas (n = 13), PRL-producing adenomas (n = 11), and nonfunctioning hormonally inactive adenomas (n = 14). No urocortin immunoreactivity was detected in these adenoma cells, except for one case of GH-producing adenoma and one case of nonfunctioning adenoma. We also performed mRNA in situ hybridization in 27 adenomas. No hybridization signals were detected in these adenomas, except in two cases. The results described above indicated that urocortin is synthesized in human anterior pituitary cells and may play an important role in biological features of normal pituitary gland, possibly as an autocrine or a paracrine regulator

Urocortin is the principal ligand for the corticotrophin-releasing factor binding protein in the ovine brain with no evidence for a sauvagine-like peptide

“…Other groups have also detected urocortin mRNA in rat pituitary (Wong et al 1996, Iino et al 1997. These findings would account for the hCRF-BP ligand activity which we detected in the fore and rear cerebral regions, the thalamic region, the pituitary and, perhaps, the brainstem (which is innervated by projections arising in the EW nucleus).…”

The role of corticotropin-releasing factor in depression and anxiety disorders

“…The highest density of urocortin innervation is observed in the lateral septum and the dorsal raphe nucleus. In a recent study, urocortin immunoreactive cells, as well as urocortin mRNA, were found in human anterior pituitary suggesting that urocortin may have a paracrine or autocrine role in the production and/or secretion of adrenohypophysial hormones (Iino et al 1997). Urocortin binds with equal affinity to both CRF receptor subtypes, but possesses much higher affinity for CRF 2 receptors than does CRF and is found in brain regions distinct from CRF.…”

ACTH response to desmopressin in a patient with acromegaly; Expression of corticotropin-releasing factor, urocortins and vasopressin V1b receptor in GH-producing pituitary adenoma

“…Following antibodies were used: the polyclonal antibodies to GH (1:800; Dakopatts, Glostrup, Denmark), ACTH (1:1600; Dakopatts), CRF (1:1000) [18], Ucn1 (1:1000) [12,19], Ucn3 (1:1000) [13], vasopressin V1b receptor (1:100, 2 µg/ mL; Santa Cruz Biotechnology, Inc., Santa Cruz, CA, USA) and monoclonal antibodies to prolactin (1:1000; Immunotech, Marseille, France), β-subunit of LH (1:1000; Immunotech), FSH (1:1000; Immunotech), TSH (1:100; Chemicon, Temecula, CA), Ki-67, clone MIB-1 (1:100, Lot.012; DAKO, Kyoto, Japan) and CAM5.2 (Becton Dickinson, San Jose, CA) [20]. The antibodies against CRF, Ucn1 and Ucn3 showed no significant cross-reaction with other CRF family peptides, respectively [11][12][13]19].…”