Abstract Adrenocorticotropic Hormone Research Articles

MON-176 Discovery and Identification of Late Stage Selective Nonpeptide ACTH Antagonists for the Treatment of Cushing’s Disease, Ectopic ACTH Secreting Tumors, and Congenital Adrenal Hyperplasia

Adrenocorticotropic hormone (ACTH) is an important modulator of steroidal hormone synthesis and secretion from the adrenal gland and its selective activity at the melanocortin type 2 receptor (MC2) dictates the synthesis and secretion of cortisol (corticosterone in rats). Excess ACTH action contribute to the pathophysiology of Cushing’s disease (CD), ectopic ACTH secreting tumors (EAS), and Congenital Adrenal Hyperplasia (CAH). Cushing’s disease results from a microadenoma derived from pituitary corticotrophic cells that secretes excess ACTH, whereas EAS arises from nonpituitary ACTH secreting tumors. Excess ACTH action at the adrenal gland and resulting hypercortisolemia presents in a myriad of symptoms that result in high morbidity. CAH results from inactivating mutations in steroid synthesis pathways, resulting in lack of cortisol and aldosterone production. Lack of negative feedback by cortisol at the level of the pituitary causes the over-secretion of ACTH, and overproduction of adrenal androgens, causing significant virilization and reduction in quality of life. We hypothesize that blocking ACTH action directly via a selective MC2 receptor antagonist may provide an important new therapeutic mechanism for these patients.To test this hypothesis, Crinetics launched an iterative medicinal chemistry program to identify potent and selective nonpeptide ACTH antagonists with pharmaceutical and safety characteristics suitable for evaluation in human clinical trials. Unlike most other G protein coupled receptors, MC2 requires the presence of an accessory protein (MRAP) for cell surface expression and recognition of ACTH. Using CHO-K cells stably expressing this MC2-MRAP complex, iterative optimization led to the discovery of multiple chemical classes of highly potent, nonpeptide MC2 receptor selective antagonist leads, which were then further optimized for drug-like characteristics. We identified multiple compounds that exhibit high potency for human and rat MC2 receptors (hMC2 Kb <1 nM), while having no activity at the MC1, MC3, MC4, or MC5 receptors. Leading ACTH antagonists were also evaluated for drug like characteristics, including good stability in liver microsomes, lack of inhibition of cytochromes P450 and the hERG ion channel, and were shown to exhibit good exposure upon oral dosing in both rats and dogs. These ACTH antagonists acutely suppress corticosterone secretion in an ACTH-challenge model in rats. In a 7-day hypercortisolemia model in which rats receive an implanted minipump that continually secretes ACTH, corticosterone levels were decreased, and body weight loss and adrenal hypertrophy were prevented with ACTH antagonist treatment. The culmination of these studies has led to a subset of candidate molecules that are being evaluated in genotoxicity, safety pharmacology, and general toxicology studies to enable evaluation in human clinical trials.

Stress signal ACTs to hinder sleep in PTSD

Adrenocorticotropic hormone (ACTH) modulation is associated with sleep disturbances in individuals with posttraumatic stress disorder.

Stability and Pharmacological Effects of Gene-Recombinant Wild Type and Mutant Human Adrenocorticotropic Hormone.

Adrenocorticotropic hormone (ACTH) is the only medicine for treating infantile spasms, however, it is catabolized rapidly. In order to make an ACTH derivative with prolonged effects, we prepared genetically engineered wild type (WT) and mutant ACTH candidates based on protease database analysis, and compared their stability and pharmacological effects. For analysis of stability, serum concentration of WT and mutant ACTH candidates were tested at different time after intravenous injection, and elimination curves were calculated to compare pharmacokinetic properties of WT and E5D-mutant ACTH. For comparison of their pharmacological effects, levels of glucocorticoids (GC) in the blood serum and secreted from cultured Y1 mouse adrenal cells were tested, and their effects on the signaling pathway mediating the expression of genes critical for GC synthesis were analyzed. The effects of ACTHs on transcription levels of the genes involved in GC synthesis were tested by qPCR. The blood concentration of E5D ACTH is higher than the WT after injection, and E5D mutation increased the t1/2 and AUC of ACTH. Pharmacological experiments showed that the effects of E5D and Y2S mutant ACTH on the production of GC and the critical signal transduction were equivalent to those of WT. WT, E5D and Y2S ACTH also have similar effects on the transcriptional levels of the genes for GC synthesis, including STAR, P450-scc, 3β-HSD, and SF-1. The stability of E5D mutant ACTH is higher than WT ACTH. The pharmacological effects of E5D ACTH is equivalent to those of WT ACTH.

Cushing's syndrome due to adrenocorticotropic hormone-secreting pheochromocytoma

Adrenocorticotropic hormone (ACTH) producing pheochromocytoma is the rare cause of Cushing's syndrome (CS). Herein, we present a 53-year-old female patient with ectopic ACTH-dependent Cushing's syndrome due to pheochromocytoma. ACTH secreting pheochromocytoma is a rare but important source of ectopic ACTH secretion. Early diagnosis of pheochromocytoma with CS needs a high index of suspicion. The scenario provides clues for a detailed discussion about the pitfalls and diagnostic difficulties in establishing the underlying cause of ACTH-dependent CS. It demonstrates relative contributions of clinical, biochemical, and radiological clues in arriving at the correct underlying cause of CS.

Epitope analysis using membrane-immobilized avidin and protein A

Adrenocorticotropic hormone (ACTH) and transferrin were trapped by biotinylated anti-ACTH antibody and anti-transferrin antibody, respectively, bound to membrane-immobilized avidin. Polypeptides with the sequences SYSMEHFR, SYSMEHFRWGKPVGK and SYSMEHFRWGKPVGKK were bound to the biotinylated anti-ACTH antibody on the membrane-immobilized avidin after the trapped ACTH was digested with trypsin on the membrane and non-binding polypeptides were washed from the membrane. Further, the polypeptides with the sequence SYSMEHFRWGKPVGK and SYSMEHFRWGKPVGKK were trapped by anti-ACTH antibody bound to membrane-immobilized protein A. The antibody recognized the WGKPVGK region of the antigen, ACTH. Polypeptide with the sequence SMGGKEDLIWELLNQAQEHFGKDK was bound to the biotinylated anti-transferrin antibody on the membrane-immobilized avidin after the trapped transferrin was digested with trypsin on the membrane and non-binding polypeptides were washed from the membrane. Further, the polypeptide with the sequence SMGGKEDLIWELLNQAQEHFGKDK was trapped by anti-transferrin antibody bound to membrane-immobilized protein A. The antibody recognized the SMGGKEDLIWELLNQAQEHFGKDK region of the antigen, transferrin. These results thus indicate that the combined methods of membrane-immobilized avidin and protein A can be applied to examine the epitopes of antigens.

Giant pituitary macroadenoma at the age of 4 months: case report and review of the literature

Adrenocorticotropic hormone (ACTH)-secreting pituitary adenoma is extremely rare. Only five cases are reported in the literature to date. We report the youngest patient of Cushing's disease due to ACTH-secreting pituitary macroadenoma at the age of 4 months. The patient presented with cushingoid facial features, hypertension and optic atrophy. Serum cortisol level was 97 microg/dl, with increased secretion of urinary free cortisol; plasma ACTH level was 353 pg/ml. Magnetic resonance imaging of the brain showed a large contrast-enhancing solid mass sitting in the sellar region, with suprasellar and lateral extension. Surgical resection was done, and immunohistochemistry confirmed the diagnosis of ACTH-secreting pituitary adenoma. Postoperatively, the patient died of disseminated intravascular coagulopathy. Cushing's disease due to ACTH-secreting pituitary macroadenoma is a possible diagnosis in early infancy. This report, along with five previously reported cases in the literature, revealed a poor surgical outcome. This surgical morbidity is possibly attributed to difficult peroperative hemostasis due to vasculopathy in Cushing's disease, which leads to excessive blood loss, adverse hemodynamic changes, myocardial dysfunction and disseminated intravascular coagulopathy.

Role of Tetrahydrobiopterin in Adrenocorticotropic Hormone‐Induced Hypertension in the Rat

Adrenocorticotropic hormone (ACTH)‐induced hypertension in the rat is characterized by nitric oxide deficiency. Tetrahydrobiopterin (BH4) is an essential cofactor for the enzyme nitric oxide synthase and glucocorticoids have been reported to reduce cytokine‐induced BH4 production. Accordingly we hypothesized that ACTH‐induced hypertension would be reversed by BH4 supplementation. Male Sprague–Dawley rats (n = 33) were treated with BH4 in vehicle (10 mg/kg/day i.p.) or vehicle alone (5 mg/kg/day i.p. of ascorbic acid in 4 mM HCl) for 10 days. ACTH (0.2 mg/kg s.c.) or saline daily injection was started 2 days after BH4 or vehicle treatment and continued for 8 days. Systolic blood pressure (SBP) was measured on alternate days using the tail cuff method. Treatment with HCl, ascorbic acid or BH4 alone had no effect on SBP. In saline treated rats, neither BH4 nor its vehicle modified SBP. In ACTH treated rats, SBP was increased in both BH4 (from 128 ± 6 to 142 ± 4 mmHg, T0 to T10, P < 0.0005, one way ANOVA) and vehicle groups (from 127 ± 3 to 158 ± 7 mmHg, T0 to T10, P < 0.001, one way ANOVA). There was no significant difference in SBP between BH4 + ACTH treated and vehicle + ACTH treated rats. Thus, daily injection of BH4 (10 mg/kg i.p.) failed to prevent the development of ACTH‐induced hypertension in rat.

ACTH expression in synovium of patients with rheumatoid arthritis and Lewis rats with adjuvant arthritis

Adrenocorticotropic hormone (ACTH) and another pro-opiomelanocortin-derived neuropeptide, β-endorphin (β-End), are stimulated by corticotropin-releasing hormone (CRH) at the anterior pituitary. CRH and β-End have predominantly proinflammatory effects in peripheral inflammatory sites. We have supposed that inflammatory stimuli develop ACTH as well as β-End. In this study, we investigated the expression of ACTH in inflamed synovial tissue from patients with rheumatoid arthritis (RA) and osteoarthritis (OA), and at inflammatory joints with adjuvant-induced arthritis (AA) in female Lewis (LEW/N) rats. The expression of ACTH immunostaining was significantly greater in synovium of RA patients than in that of OA patients (P < 0.0001), and correlated with the extent of inflammatory mononuclear cell infiltration. Extensive and intense intracellular ACTH immunostaining, which correlated with the advance in arthritis score, was observed in the synovial lining layer, inflammatory mononuclear cells, and fibroblast-like cells of synovium and chondrocytes in LEW/N rats with AA. In addition, we performed double immunostaining of the same sections from arthritic joints in rats with anti-ACTH and anti-CRH antibodies. ACTH and CRH colocalized in inflammatory mononuclear cells and fibroblast-like cells. ACTH may play a role in the pathogenesis of RA as well as CRH.

Characterization of an Acth-Induced Chloride Current in Rat Adrenal Zona Glomerulosa Cells

Adrenocorticotropic hormone (ACTH) is one of the principal activator of aldosterone secretion in rat zona glomerulosa cells, but its action on chloride currents is not well established. Here, we demonstrate that the hormone provoked a transient increase in a chloride current with a small unitary conductance estimated at 3.35 pS. Amplitude, as well as time-dependent increase of the ACTH-induced chloride current was independent of the intracellular cAMP concentration. In contrary, its decrease was sensitive to alkaline phosphatase and PKA-inhibitor H-89, indicating that protein phosphorylation, at least in part via PKA, is involved in the decline of the current.

Protocol for ACTH administration in refractory childhood seizures: educational strategies.

Adrenocorticotropic hormone (ACTH) in gel form is increasingly being used in the treatment of a variety of childhood seizure disorders. The therapy involves intramuscular injections and can be associated with significant morbidity. A teaching/learning plan for parents or caregivers based on Knowles' theory of adult learning was developed and incorporated into the ACTH protocol presented here. Twenty-nine families completed this protocol. Despite a wide range of educational levels and support systems, all caregivers proved capable of administering the medication. Few complications were encountered. In interviews with the caregivers regarding the teaching-learning process, caregivers believed it contributed to their ability to complete the therapeutic program.

ACTH in the pigeon vestibular ganglion.

Adrenocorticotropic hormone (ACTH) is a member of the opiocortin family of peptides. Within the central nervous system, ACTH-synthesizing neurons are generally considered to be located within the hypothalamus and are known to be involved in the neural circuitry underlying the integration of stress responses. We now report the existence of ACTH-positive perikarya within the pigeon vestibular ganglion. This result makes it likely that ACTH may act in other systems as a transmitter/modulator outside a stress-related context. Since the vestibular ganglia of mammals are known to be glutaminergic, the present data further extends possibility that ACTH is co-localized with glutamate.

Cushing's Ulcer as a Consequence of Adrenocorticotropic Hormone Administration for Infantile Spasms

Adrenocorticotropic hormone (ACTH) is the treatment of choice for infantile spasms despite its multiple side effects. This case represents a previously unreported side effect, peptic ulceration, occurring during ACTH treatment of infantile spasms. Two pathophysiologic mechanisms are proposed and examined. A direct effect of ACTH on the duodenum is considered but deemed unlikely. Alternatively, the combination of the patient's communicating hydrocephalus and ACTH's central effects is proposed to have led to increased intracranial pressure and a Cushing's ulcer. The need for pretreatment neuroimaging and H2-receptor antagonist use during ACTH therapy in all cases, along with gastrin level measurements in selected cases, is recommended.

Acidemia stimulates ACTH, vasopressin, and heart rate responses in fetal sheep

Adrenocorticotropic hormone (ACTH), arginine vasopressin (AVP), and renin responses to hemorrhage are highly correlated to the hemorrhage-induced decreases in arterial pH. The present study was designed to test the responses of these three systems to acute fetal acidemia, produced by intravenous infusion of H+. HCl was infused into chronically catheterized fetal sheep at rates of 0.02 (n = 5), 0.10 (n = 6), and 0.50 (n = 5) meq/min. Infusions at rates of 0.10 and 0.50 meq/min significantly decreased fetal arterial pH and increased arterial PCO2. Fetal heart rate and plasma concentrations of ACTH, cortisol, and AVP were significantly increased during infusion of HCl at 0.5 meq/min. Neither fetal plasma renin activity nor fetal arterial blood pressure was significantly altered by any of the infusions. The results of these experiments suggest that fetal ACTH, AVP, and heart rate are stimulated by decreases in arterial pH and/or increases in arterial PCO2. We speculate that these responses are chemoreceptor mediated, although we cannot distinguish the apparent relative roles of peripheral and central chemoreceptors on the basis of the present study.

Human ACTH, beta-lipotropin and beta-endorphin levels in maternal plasma at delivery.

Adrenocorticotropic hormone (ACTH), beta-lipotropin (beta-LPH) and beta-endorphin (beta-EP) were measured simultaneously in maternal plasma at delivery. Mean concentrations of beta-LPH and beta-EP in maternal plasma at delivery were significantly higher than those in normal control. There were significant positive correlations among ACTH, beta-LPH and beta-EP concentrations, respectively. These data suggest that beta-LPH and beta-EP were elevated during delivery and in parallel with each other.