Effects of a Novel Corticotropin-Releasing-Hormone
Total Page:16
File Type:pdf, Size:1020Kb
Molecular Psychiatry (2000) 5, 137–141 2000 Macmillan Publishers Ltd All rights reserved 1359-4184/00 $15.00 www.nature.com/mp IMMEDIATE COMMUNICATION Effects of a novel corticotropin-releasing-hormone receptor type I antagonist on human adrenal function HS Willenberg1, SR Bornstein2, N Hiroi2,GPa¨th1, PE Goretzki3, WA Scherbaum1 and GP Chrousos2 1Diabetes Research Institute at the University of Du¨sseldorf, Germany; 2National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA; 3Department of Surgery at the University of Du¨sseldorf, Germany Corticotropin-releasing hormone (CRH) is the principal regulator of the hypothalamic-pitu- itary-adrenal (HPA) axis and an activator of the sympathoadrenal (SA) and systemic sympath- etic (SS) systems. Mental disorders, including major depression and, more recently, Alzhei- mer’s disease have been associated with dysregulation of the HPA axis and the SA/SS systems. Treatment of rats or monkeys with the novel CRH receptor type 1 (CRH-R1) antagon- ist antalarmin inhibits the HPA and/or the SA/SS axes. This is the first study to examine the potential direct effect of antalarmin on human adrenal function. Adrenocortical and adreno- medullary cells were characterized by double-immunohistochemistry with anti-17 ␣ hydroxylase (cortical cells) and anti-chromogranin A (chromaffin cells). Expression of CRH, ACTH, CRH type I and type II receptor mRNA were analyzed by reverse-transcription (RT) PCR. Human adrenal cortical and/or chromaffin cells in co-culture were incubated with CRH, antalarmin, and both CRH and antalarmin in vitro. Exposure of these cells to corticotropin or vehicle medium served as positive and negative controls, respectively. Cortical and chromaf- fin tissues were interwoven in the human adrenals, and both in situ and in the co-culture system the endocrine cell types were in close cellular contact. ACTH, CRH, and CRH-R1 and CRH-R2 mRNAs were expressed in the human adrenal as determined by RT-PCR. CRH (10−8 M) led to a moderate increase of cortisol release (145.7 ± 20.0%) from cortical and chromaffin adrenal cells in co-culture. This effect corresponded to 41.8% of the maximal increase induced by ACTH (10−8 M). The action of CRH was completely inhibited by antalarmin. CRH, ACTH, and both CRH-R1 and CRH-R2 mRNAs are expressed in the adult human adrenal gland. CRH stimulates cortisol production in cortical and chromaffin cell co-cultures. This effect is blocked by antalarmin, a selective CRH-R1 receptor antagonist, suggesting that CRH-R1 receptors are involved in an intraadrenal CRH/ACTH control system in humans. Molecular Psy- chiatry (2000) 5, 137–141. Keywords: CRH; CRH-receptor antagonist; human; adrenal Introduction system.6,7 Since several mental disorders, including melancholic depression,8 anxiety disorders,9,10 and Corticotropin-releasing hormone (CRH) and its recep- Alzheimer’s disease,8 are associated with hyperactiv- tors are widely expressed in the brain and peripheral ation of the HPA axis and the sympathetic system, it tissues.1–3 This hormone is the principal regulator of is of major interest to identify substances which selec- the hypothalamic-pituitary-adrenal (HPA) axis2 and tively inhibit the activity of these systems. Because of exerts its effects via two main receptor subtypes, type its chemical structure, its oral actions, and its ability 1 (CRH-R1)3 and 2 (CRH-R2).4 CRH also activates both to cross the blood–brain barrier, the novel CRH-R1 the adrenomedullary and systemic sympathetic system antagonist antalarmin holds promise in the treatment of limbs and an intraadrenal CRH/ACTH/cortisol system disorders associated with an increased CRH drive.11–13 has been postulated.5 Recently, the CRH-R1 has been This is the first study to examine the direct effect of demonstrated in mid-gestation human fetal adrenals the CRH-R1 antagonist antalarmin on human adrenal and CRH has been shown to stimulate directly adrenal cortical and/or medullary cells in vitro. steroidogenesis in human fetal adrenal cells via the phospholipase C-inositol phosphate second messenger Materials and methods Materials Correspondence: SR Bornstein, MD, National Institute of Child Normal human adrenal glands (n = 4) were surgically Health and Human Development, Pediatric and Reproductive Endocrinology Branch, National Institutes of Health, Bethesda, removed along with one kidney for renal carcinoma. Maryland 20892, USA. E-mail: BornsteSȰcc1.nichd.nih.gov Excised tissues were transferred to prechilled phos- Received 1 December 1999; accepted 13 December 1999 phate-buffered saline, pH 7.6, and kept on ice until Effects of antalarmin on human adrenal function HS Willenberg et al 138 further treatment. In addition, the human adrenocort- plus antalarmin (10−7 M), or vehicle medium served as ical cell line NCI-H295 was employed to test the effects positive and negative controls. NCI-H295 human adre- of antalarmin on cortisol secretion of pure adrenocort- nocortical carcinoma cells were treated in the same ical cells. manner. Culture supernatants were radioimmuno- assayed (Biermann, Germany) for cortisol content. Immunohistology Results are given as a percentage of basal secretion ± Adrenocortical and chromaffin cells were charac- SEM. Intra- and inter-assay coefficients were less than terized by single and double immunohistochemistry 5%. Statistical analysis was performed employing the using paraffin-embedded tissue samples and cultured two-tailed Student’s t-test with Welch’s correction. cells. The labelled streptavidin-biotin-peroxidase reac- Antalarmin, N-butyl-N-ethyl-[2,5,6-trimethyl-7-(2,4,6- tion (DAKO, Hamburg, Germany) was combined with trimethylphenyl)-7H-pyrrolo[2,3-d]pyri-midin-4-yl]amine, the DAB chromogen and the peroxidase-anti-peroxi- was synthesized, purified, and tested in a receptor dase method (DAKO) with the AEC chromogen. binding assay as previously reported.16 Cortical cells were identified with a specific rabbit anti- body to 17-alpha hydroxylase (courtesy of MR Water- man, Nashville, USA) and chromaffin cells with a spe- cific monoclonal mouse antibody to chromogranin A Results (DAKO) as described previously.14,15 Cortical and chromaffin cells were interwoven to a Reverse-transcription PCR great degree in human adrenal glands as visualized by Human adrenal mRNA (1 g) which was purchased double immunohistochemistry (Figure 1a). In the co- from Clontech (Palo Alto, CA, USA) was reversely tran- culture system, human adrenocortical cells showed a scribed to cDNA in a first step according to the instruc- positive staining signal for anti-17-alpha hydroxylase tions of the first strand cDNA synthesis kit (Roche immunoglobulin and were documented to be in direct Diagnostics, Mannheim, Germany). For PCR amplifi- contact with adrenomedullary cells (Figure 1b). Intra- cation, we used the CRH, CRH-R1, and CRH-R2 pri- adrenal CRH (122-bp fragment) and ACTH (77-bp mers listed in Table 1, and applied the conditions as fragment) mRNA were found to be expressed as evi- follows: 40 thermal step cycles of denaturation at 94°C denced by RT-PCR (Figure 2a). The expression of CRH- for 1 min, annealing at 60°C for 1 min, and elongation R1 mRNA (592-bp fragment) (Figure 2b) and CRH-R2 at 72°C for 2 min. For the ACTH primer, all conditions mRNA (Figure 2c) could be documented for adrenal were identical except for the annealing temperature, and as a positive control in pituitary tissue. Antalarmin which was 55°C. For positive control, we used mRNA at 10−7 M did not affect basal cortisol secretion from from pituitary gland (Clontech). For negative control, cells of the adrenocortical cell line NCI-H295 and from we amplified preparations skipping the RT step. adrenal cells in primary cultures (100.4 ± 9.0% of basal secretion) (Figure 3). ACTH at 10−8 M led to a maximal Co-culture system increase in cortisol secretion from cultured adrenal For in vitro studies adrenal tissue was mechanically cells (209.3 ± 15.4%, P Ͻ 0.001) which was not blocked dissected and enzymatically digested. Both medullary by antalarmin (188.5 ± 73.6%, P Ͻ 0.05) (Figure 3a). and cortical cells were dispersed in culture wells as CRH (10−8 M) led to a moderate increase of cortisol described previously.14,15 Briefly, after 3 days of undis- secretion of 145.7 ± 20.0% from mixed adrenal cells (P turbed growth, cells were washed and subjected to Ͻ 0.05), but not from pure adrenocortical cells. The incubation with CRH (10−8 M), antalarmin (10−7 M), CRH-mediated increase was completely blocked by co- and CRH (10−8 M) plus antalarmin (10−7 M) for 12 h. incubation with antalarmin (109.8 ± 19.9%) (Figure Exposure of cells to ACTH (10−8 M), ACTH (10−8 M) 3b). Table 1 Primer sequences, products size and primer specific conditions Primer Primer sequences (5Ј–3Ј) Product Cycles Ta CRH S TCCGAGGAGCCTCCCATC 122 bp 40 cycles 60°C AS AATCTCCATGAGTTTCCTGTTGC ACTH S CACTTCCGCTGGGGCAAGCC 77 bp 40 cycles 55°C AS GACTCGTCCTCGGCGCCGTT CRH-R1 S ACAAACAATGGCTACCGGGA 592 bp 40 cycles 60°C AS TCATGGGGCCCTGGTAGAT CRH-R2 S TGTGGAAGGCTGCTACCTG 615 bp 40 cycles 60°C AS GTCTGCTTGATGCTGTGGAA S, sense primer; AS, antisense primer; bp, base pairs; Ta, annealing temperture; CRH-R1, CRH-type I receptor; CRH-R2, CRH- type II receptor. Molecular Psychiatry Effects of antalarmin on human adrenal function HS Willenberg et al 139 a b Figure 2 RT-PCR analysis of human adrenal and pituitary messenger RNA. (a) Human adrenal gland expresses the CRH and ACTH mRNA. The 122-bp (arrow head) and 77-bp (arrow) RT-PCR amplified products correspond to the CRH and ACTH predicted bands. (b) Expression of the CRH-R1 gene in human adrenal and pituitary gland. RT-PCR product of 592 bp (arrow) from both adrenal gland and pituitary gland. (c) Expression of the CRH-R2 gene in human adrenal and pitu- itary gland, showing RT-PCR product of 615-bp fragments (arrow) from both adrenal gland and pituitary gland.