Endocrine Abstracts

Introduction: There is a large body of evidence to suggest that the GH axis plays an important role in brain myelination. However, results from studies in humans with an abnormal GH axis have varied and therefore there remains no consensus as to whether the GH/IGF1 axis plays a significant role in neural development. No previous studies have used diffusion tensor imaging (DTI) a sensitive magnetic resonance imaging (MRI) technique for studying brain white matter tracts, to add...

Background: Familial glucocorticoid deficiency (FGD) is an autosomal recessive disorder resulting from resistance to the action of ACTH on the adrenal cortex to produce glucocorticoids. Affected individuals are deficient in cortisol and, if untreated, are likely to succumb to hypoglycemia or overwhelming infection in infancy or childhood. Mutations of the ACTH receptor (melanocortin 2 receptor, MC2R) or the melanocortin 2 receptor accessory protein (MRAP), FGD types 1 & 2 ...

Background: Russell–Silver syndrome (RSS) is a heterogeneous condition characterised by pre- and post-natal growth retardation in association with variable dysmorphic features including triangular facies and body asymmetry. The condition has previously been linked to 2 genetic abnormalities: aberrant methylation at the 11p15.5 locus in 30–40% and maternal uniparental disomy (UPD) of chromosome 7 in 10% of cases. Up to 50% of children currently have no identified (epi...

Background: The identification of MRAP in 2005 as the first melanocortin-2-receptor (MC2R)/ACTH receptor accessory protein provided insight into the regulation of the melanocortin receptor system. Mutations in MRAP cause Familial glucocorticoid deficiency, an autosomal recessive disorder resulting in isolated cortisol deficiency. In vitro studies showed that MRAP was essential for the functional expression of the MC2R. The melanocortin receptor (MCR) family (MC1R to MC5...

MC2R is the smallest member of the GPCR superfamily and belongs to the melanocortin subfamily of receptors. The pituitary hormone ACTH acts through MC2R to induce the intracellular production cAMP and the stimulation of steroidogenesis. We have previously shown that MC2R interacts with a single-transmembrane domain protein called MRAP (melanocortin-2 receptor accessory protein) and is required for the functional expression of MC2R. Both MC2R and MRAP are mutated in the rare re...

Stress results in activation of the hypothalamic–pituitary–adrenal axis with increased circulating cortisol. It has been argued that a syndrome of ‘relative adrenal insufficiency’ is common in critically ill patients. Patients who fail to increase their cortisol by >250 nmol/30 min following the administration of 250 μg ACTH in the short synacthen test (SST) have been reported to have a higher mortality (JAMA 2000, 283 1038–1045)...

The melanocortin-2-receptor accessory protein (MRAP) is a type I integral transmembrane protein required for the functional expression of the melanocortin-2-receptor (MC2R).Here we have investigated the expression and biochemical properties of mouse MRAP. Initially, mouse MRAP and MC2R tissue expression were determined by RT-PCR, being only present in the adrenal gland and fat tissue. Then, by in situ hybridisation studies using a full-length MRAP...

Attenuation of the adrenocortical response to ACTH in septic shock is a well recognised phenomenon, although the underlying mechanisms remain poorly understood. The evidence points towards factors in septic serum that dampen the adrenocortical responsiveness. The aim of this work is to investigate the cellular function of adrenocortical cells in septic shock and to determine the components within serum that could influence their function. Septic rat serum was collected from ma...

Late onset Cushing’s disease, occurring years following the diagnosis of a silent corticotroph adenoma (SCA) is rare, with very few previously reported cases. We present a series of 5 subjects with SCA, aggressive tumour recurrences and late onset Cushing’s disease.The mean age of subjects at initial presentation was 41 yrs (35–52), sex 3:2 (M:F). There were no clinical features of hypercortisolism at diagnosis. Two subjects had hypocortis...

Familial glucocorticoid deficiency (FGD) is a rare autosomal recessive disease resulting from adrenal unresponsiveness to ACTH. Patients present in early childhood with hyperpigmentation, hypoglycaemic episodes and seizures secondary to glucocorticoid deficiency. If left untreated this condition is fatal. Mineralocorticoid production is normal. Mutations in the ACTH receptor have been well described and account for approximately 25% of cases. We describe 3 additional novel mut...