Expression of the IGF system in human adrenal tissues from early infancy to late puberty: implications for the development of adrenarche

An integrated single-cell analysis of human adrenal cortex development

The adrenal glands synthesize and release essential steroid hormones such as cortisol and aldosterone, but many aspects of human adrenal gland development are not well understood. Here, we combined single-cell and bulk RNA sequencing, spatial transcriptomics, IHC, and micro-focus computed tomography to investigate key aspects of adrenal development in the first 20 weeks of gestation. We demonstrate rapid adrenal growth and vascularization, with more cell division in the outer definitive zone (DZ). Steroidogenic pathways favored androgen synthesis in the central fetal zone, but DZ capacity to synthesize cortisol and aldosterone developed with time. Core transcriptional regulators were identified, with localized expression of HOPX (also known as Hop homeobox/homeobox-only protein) in the DZ. Potential ligand-receptor interactions between mesenchyme and adrenal cortex were seen (e.g., RSPO3/LGR4). Growth-promoting imprinted genes were enriched in the developing cortex (e.g., IGF2, PEG3). These findings reveal aspects of human adrenal development and have clinical implications for understanding primary adrenal insufficiency and related postnatal adrenal disorders, such as adrenal tumor development, steroid disorders, and neonatal stress.

Normal and Premature Adrenarche

Adrenarche is the maturational increase in adrenal androgen production that normally begins in early childhood. It results from changes in the secretory response to adrenocorticotropin (ACTH) that are best indexed by dehydroepiandrosterone sulfate (DHEAS) rise. These changes are related to the development of the zona reticularis (ZR) and its unique gene/enzyme expression pattern of low 3ß-hydroxysteroid dehydrogenase type 2 with high cytochrome b5A, sulfotransferase 2A1, and 17ß-hydroxysteroid dehydrogenase type 5. Recently 11-ketotestosterone was identified as an important bioactive adrenarchal androgen. Birth weight, body growth, obesity, and prolactin are related to ZR development. Adrenarchal androgens normally contribute to the onset of sexual pubic hair (pubarche) and sebaceous and apocrine gland development. Premature adrenarche causes ≥90% of premature pubarche (PP). Its cause is unknown. Affected children have a significantly increased growth rate with proportionate bone age advancement that typically does not compromise growth potential. Serum DHEAS and testosterone levels increase to levels normal for early female puberty. It is associated with mildly increased risks for obesity, insulin resistance, and possibly mood disorder and polycystic ovary syndrome. Between 5% and 10% of PP is due to virilizing disorders, which are usually characterized by more rapid advancement of pubarche and compromise of adult height potential than premature adrenarche. Most cases are due to nonclassic congenital adrenal hyperplasia. Algorithms are presented for the differential diagnosis of PP. This review highlights recent advances in molecular genetic and developmental biologic understanding of ZR development and insights into adrenarche emanating from mass spectrometric steroid assays.

Molecular Mechanisms of Functional Adrenocortical Adenoma and Carcinoma: Genetic Characterization and Intracellular Signaling Pathway

The adrenal cortex produces steroid hormones as adrenocortical hormones in the body, secreting mineralocorticoids, glucocorticoids, and adrenal androgens, which are all considered essential for life. Adrenocortical tumors harbor divergent hormonal activity, frequently with steroid excess, and disrupt homeostasis of the body. Aldosterone-producing adenomas (APAs) cause primary aldosteronism (PA), and cortisol-producing adenomas (CPAs) are the primary cause of Cushing’s syndrome. In addition, adrenocortical carcinoma (ACC) is a highly malignant cancer harboring poor prognosis. Various genetic abnormalities have been reported, which are associated with possible pathogenesis by the alteration of intracellular signaling and activation of transcription factors. In particular, somatic mutations in APAs have been detected in genes encoding membrane proteins, especially ion channels, resulting in hypersecretion of aldosterone due to activation of intracellular calcium signaling. In addition, somatic mutations have been detected in those encoding cAMP-PKA signaling-related factors, resulting in hypersecretion of cortisol due to its driven status in CPAs. In ACC, mutations in tumor suppressor genes and Wnt-β-catenin signaling-related factors have been implicated in its pathogenesis. In this article, we review recent findings on the genetic characteristics and regulation of intracellular signaling and transcription factors in individual tumors.

Insulin-like growth factor 1 of wild vertebrates in a life-history context

Broad variation in intra- and interspecific life-history traits is largely shaped by resource limitation and the ensuing allocation trade-offs that animals are forced to make. Insulin-like growth factor 1 (IGF-1), a growth-hormone-dependent peptide, may be a key player in the regulation of allocation processes. In laboratory animals, the effects of IGF-1 on growth- and development (positive), reproduction (positive), and longevity (negative) are well established. We here review the evidence on these effects in wild vertebrates, where animals are more likely to face resource limitation and other challenges. We point out the similarities and dissimilarities in patterns of IGF-1 functions obtained in these two different study settings and discuss the knowledge we need to develop a comprehensive picture of the role of IGF-1 in mediating life-history variation of wild vertebrates.

Role of estrogen receptors in modulating aldosterone biosynthesis and blood pressure

Blood pressure is lower in premenopausal women than in age-matched men; after menopause blood pressure values and the prevalence of hypertension show opposite trends indicating that estrogens contribute to maintaining normal blood pressure values in women. In experimental studies menopause increases aldosterone levels, an effect alleviated by estrogen treatment. We have recently discovered a role of estrogen receptors (ER) in controlling aldosterone biosynthesis in the human adrenocortical zona glomerulosa, which expresses both the classical ERα and β receptors and G protein-coupled estrogen receptor (GPER). We have also identified that GPER mediates an aldosterone-induced aldosterone response. We found that 17 β-estradiol exerts a dual effect: it blunts aldosterone production via ERβ, but displays a potent aldosterone secretagogue effect via GPER activation after ERβ blockade. Thus, in premenopausal women high estrogen levels might tonically blunt aldosterone synthesis via ERβ, thereby maintaining normal blood pressure; after menopause loss of this estrogen-mediated inhibition can contribute to increasing blood pressure via GPER-mediated aldosterone release. The additional findings that GPER mediates an aldosterone-induced stimulation of aldosterone biosynthesis and that GPER predominates in aldosterone-producing adenomas strongly involves this receptor in the pathophysiology of primary aldosteronism. Our purpose here was to provide an update on estrogen receptor function in the normal adrenal cortex and its relevance for the sex differences in blood pressure in light of the newly discovered role of GPER in regulating aldosterone synthesis. The implications of the novel knowledge for the treatment of estrogen-dependent malignancies with ER modulators are also discussed.

Glucocorticoid-activation system mediated glucocorticoid-insulin-like growth factor 1 (GC-IGF1) axis programming alteration of adrenal dysfunction induced by prenatal caffeine exposure

Glucocorticoids play a major factor in fetal maturation and fate decision after birth. We have previously demonstrated that prenatal caffeine exposure (PCE) resulted in adrenal dysplasia. However, its molecular mechanism has not been clarified. In the present study, a rat model of intrauterine growth retardation (IUGR) was established by PCE, and offspring were sacrificed. Moreover, NCI-H295 A cells were used to confirm glucocorticoid-related molecular mechanism. Results showed that PCE fetal weight decreased, and the IUGR rate increased, while serum corticosterone levels increased but insulin-like growth factor 1 (IGF1) levels decreased. Fetal adrenals exhibited an activated glucocorticoid-activation system, and the downregulated expression of IGF1 signal pathway and steroidal synthetases. For adult rats, there was no significant change in the glucocorticoid-activation system in the PCE group, the IGF1 signal pathway showed increased trend, and the expression levels of adrenal steroidal synthetases were close to normal. The data in vitro showed that the cortisol of 1200 nM can inhibit the expression of adrenocortical cell steroidal synthetases and IGF1 signal pathway when compared with the control. Meanwhile, the glucocorticoid-activation system was activated while GR inhibitor mifepristone can reverse the effect of cortisol. Furthermore, cortisol can also promote GR into the nucleus after its activation. Based on these findings, we speculated that high concentrations of glucocorticoid in utero led to GR in the nucleus through its activation and then inhibited the IGF1 signaling pathway by activating the glucocorticoid-activation system, which could further downregulate steroid synthesis.

Human Adrenal Cortex: Epigenetics and Postnatal Functional Zonation

The human adrenal cortex, involved in adaptive responses to stress, fluid homeostasis, and secondary sexual characteristics, arises from a tightly regulated development of a zone and cell type-specific secretory pattern. However, the molecular mechanisms governing adrenal zonation, particularly postnatal zona reticularis development, which produce adrenal androgens in a lifetime-specific manner, remain poorly understood. Epigenetic events, including DNA and histone modifications as well as regulation by noncoding RNAs, are crucial in establishing or maintaining the expression pattern of specific genes and thus contribute to the stability of a specific differentiation state. Emerging evidence points to epigenetics as another regulatory layer that could contribute to establishing the adrenal zone-specific pattern of enzyme expression. Here, we outline the developmental milestones of the human adrenal cortex, focusing on current advances and understanding of epigenetic regulation of postnatal functional zonation. Numerous questions remain to be addressed emphasizing the need for additional investigations to elucidate the role of epigenetics in the human adrenal gland. Ultimately, improved understanding of the epigenetic factors involved in adrenal development and function could lead to novel therapeutic interventions.

The role of insulin-like growth factor system in the adrenocortical tumors

INTRODUCTION

The different presentation of adrenocortical tumors in benign adenoma (ACA) or adrenocortical carcinoma (ACC) is related to the variability at the molecular level. The insulin-like growth factor (IGF) system is one of the most frequently altered pathways in ACC. In this review we will critically analyze the evidence regarding the pathogenic role of the IGF system in adrenal tumorigenesis, focusing on ACC. We will also examine the preclinical and clinical studies which investigated the targeting of the IGF system as a therapeutic approach in ACC.

EVIDENCE ACQUISITION

The IGF system plays a crucial role in the embryogenesis of adrenal glands. No significant alterations of the IGF system were observed in ACA. In ACC, the IGF2 overexpression is one of the most frequent molecular change presented in more than 85% of cases. However, IGF2 seems to be only a tumor progression factor which requires additional hits to trigger adrenal tumorigenesis. Also, the IGF1 receptor (IGF1R) appears to be higher expressed in ACC. Many IGF1R target-drugs have been developed to inhibit the activation of the IGF system.

EVIDENCE SYNTHESIS

Preclinical studies using antibody or tyrosine kinase which target the IGF1R, or the dual-targeting of IGF1R and insulin receptor (IR) reduced ACC cells proliferation both in vitro and in vivo in mouse xenograft model. However, these promising results were not confirmed in clinical trials.

CONCLUSIONS

Nowadays, predictive markers for the response of target-IGF therapy are missing and further studies which investigate new molecular markers and evaluate the entire IGF receptors, including the IR, are urgently needed.

Association between Body Mass Index and Serum Dehydroepiandrosterone Sulfate Level in 8-Year-Old Girls

Background

Adiposity may play a role as a potential trigger for adrenarche. The purpose of this study was to evaluate the association between body mass index (BMI) and serum dehydroepiandrosterone sulfate (DHEAS) level.

Methods

The medical records of 8-year-old girls who presented to our clinic between 2014 and 2016 with concerns regarding pubertal changes were retrospectively reviewed. The 192 girls were divided into two groups depending on activation of the hypothalamic-pituitary-gonadal (HPG) axis. Group I included 77 subjects with a breast Tanner stage 1 with unknown HPG axis or thelarche without activated HPG axis. Group II included 115 subjects with activated HPG axis. Serum DHEAS level ≥1.1 μmol/L was regarded as biochemical adrenarche.

Results

Based on correlation analyses, BMI standard deviation score (SDS) was positively correlated with height SDS, bone age divided by chronological age (BA/CA), and DHEAS level in all subjects (r=0.269, r=0.270, r=0.298; all P<0.001, respectively). BMI SDS was negatively correlated with peak luteinizing hormone level in group II (r=−0.236, P=0.011). Based on multiple linear regression analyses, BMI SDS was associated with serum DHEAS level in all subjects (β=0.280, P<0.001), group I (β=0.415, P=0.001), and group II (β=0.206, P=0.030). DHEAS level was also associated with BA/CA in all subjects (β=0.402, P<0.001), group I (β=0.494, P<0.001), and group II (β=0.347, P<0.001).

Conclusion

BMI SDS was associated with DHEAS level, which was associated with BA/CA. Childhood obesity may influence the development of adrenarche, which may contribute to advanced skeletal maturation.

Associations of lifestyle factors with serum dehydroepiandrosterone sulphate and insulin-like growth factor-1 concentration in prepubertal children

OBJECTIVE

Little is known about the relationships of dietary factors, physical activity and sedentary behaviour to dehydroepiandrosterone sulphate (DHEAS) and insulin-like growth factor-1 (IGF-1) concentrations among prepubertal children. Therefore, we studied the associations of these lifestyle factors with serum DHEAS and IGF-1 in children.

DESIGN AND SUBJECTS

Cross-sectional analysis of a population sample of 431 prepubertal children aged 6-9 years.

MEASUREMENTS

Assessment of dietary factors by food records and physical activity and sedentary behaviour by a combined heart rate and movement monitor and a questionnaire. Measurement of serum DHEAS and IGF-1.

RESULTS

Consumption of low-fibre grain products (standardized regression coefficient β = .118, P = .017) and intake of vegetable protein (β = .100, P = .045) was positively and consumption of sugar-sweetened beverages (β = -.117, P = .018) was inversely associated with DHEAS after adjustment for sex, age and body fat percentage. Energy intake (β = .160, P = .001) was positively associated with IGF-1 adjusting for sex, age and body fat percentage. Vigorous physical activity was inversely associated with DHEAS after adjustment for sex and age (β = -.120, P = .027), and total (β = -.137, P = .007), moderate (β = -.130, P = .012), vigorous (β = -.136, P = .011) and moderate to vigorous physical activity (β = -.160, P = .003) were inversely and total sedentary behaviour (β = .151, P = .003) was positively associated with IGF-1 adjusting for sex and age. None of physical activity measures was associated with DHEAS or IGF-1 after additional adjustment for body fat percentage.

CONCLUSIONS

Lifestyle factors have weak and moderate associations with biochemical markers of adrenarche in prepubertal children. These associations indicate body fat independent and dependent influences of diet and physical activity, respectively.

IGF1/MAPK/ERK signaling pathway-mediated programming alterations of adrenal cortex cell proliferation by prenatal caffeine exposure in male offspring rats

Our previous study proposed a glucocorticoid-insulin-like growth factor 1 (GC-IGF1) axis programming mechanism for prenatal caffeine exposure (PCE)-induced adrenal developmental dysfunction. Here, we focused on PCE-induced cell proliferation changes of the adrenal cortex in male offspring rats before and after birth and clarified the intrauterine programming mechanism. On gestational day (GD) 20, the PCE group had an elevated serum corticosterone level reduced fetal bodyweight, maximum adrenal sectional area, and elevated adrenal corticosterone and aldosterone contents. However, in postnatal week (PW) 6, the serum corticosterone level was decreased, and the bodyweight, with catch-up growth, adrenal cortex maximum cross-sectional area and aldosterone content were relatively increased, while the adrenal corticosterone content was lower. On GD20, the expression of adrenal IGF1, IGF1R and proliferating cell nuclear antigen (PCNA) were decreased, while the expression of these factors at PW6 were increased in the PCE group. Fetal adrenal gene chip analysis suggested that the mitogen-activated protein kinase/extracellular regulated protein kinase (MAPK/ERK) signal pathway was suppressed in the PCE group. Moreover, in the rat primary adrenal cells, corticosterone (rather than caffeine) was shown to significantly inhibit cell proliferation, IGF1 and PCNA expression, and ERK phosphorylation, which could be reversed by exogenous IGF1. Meanwhile, the effects of exogenous IGF1 were reversed by the ERK pathway inhibitor (PD184161). In conclusion, PCE could induce programming alterations in adrenal cortical cell proliferation before and after birth in male offspring rats. The underlying mechanism is associated with the inhibition of fetal adrenal IGF1-related MAPK/ERK signaling pathway caused by high glucocorticoid levels.

Adrenarche in Silver-Russell Syndrome: Timing and Consequences

OBJECTIVES

Premature adrenarche has been reported to be frequent in Silver-Russell syndrome (SRS), but systematic studies are lacking. Here, we studied the prevalence of early adrenarche in SRS, potential predictors, and consequences based on cases with long-term follow-up.

DESIGN AND SETTING

This retrospective longitudinal single-center study included 62 patients with SRS (34 boys) with documented age at adrenarche and positive Netchine-Harbison clinical score who were seen during the past 20 years with a median follow-up of 12.8 years. Clinical and biochemical characteristics were collected from patient records. Adrenarche was defined by reaching a serum dehydroepiandrosterone concentration >500 ng/mL.

RESULTS

Boys reached adrenarche at a median age of 9.2 years (quartiles: 7.6, 10.9 years) and pubarche at a median age of 11.7 years (quartiles: 10.7, 12.8 years). Girls reached adrenarche at a median age of 8.1 years (quartiles: 6.6, 10.1 years) and pubarche at a median age of 9.8 years (quartiles: 8.3, 10.8). Premature adrenarche occurred in 13% of the patients. Multiple linear regression analysis revealed that early adrenarche was associated with early initiation of recombinant human growth hormone (rhGH) treatment (P = 0.0024 in boys; P = 0.0195 in girls), but not with the Netchine-Harbison clinical score (P > 0.25). Response to rhGH treatment (median dose, 50 µg/kg/d) and adult height (n = 43) were not compromised by early adrenarche.

CONCLUSIONS

Early or premature adrenarche was more frequent in SRS than in the general population and was associated with early age at initiation of rhGH treatment. Response to rhGH treatment and adult height were not compromised by early adrenarche.

DNA methylation is not involved in specific down-regulation of HSD3B2, NR4A1 and RARB genes in androgen-secreting cells of human adrenal cortex

We hypothesized that DNA methylation is involved in human adrenal functional zonation. mRNAs expression and methylation pattern of RARB, NR4A1 and HSD3B2 genes in human adrenal tissues (HAT) and in pediatric virilizing adrenocortical tumors (VAT) were analyzed. For analysis of the results samples were divided into 3 age groups according to FeZ involution, pre and post-adrenarche ages. In all HAT, similar RARB mRNA was found including microdissected zona reticularis (ZR) and zona fasciculata, but HSD3B2 and NR4A1 mRNAs were lower in ZR (p < 0.05). NR4A1 and RARB promoters remained unmethylated in HAT and VAT. No adrenal zone-specific differences in NR4A1 methylation were observed. In summary, RARB was not associated with ZR-specific downregulation of HSD3B2 in postnatal human adrenocotical zonation. DNA methylation would not be involved in NR4A1 adrenocortical cell-type specific downregulation. Lack of CpG islands in HSD3B2 suggested that HSD3B2 ZR-specific downregulation would not be directly mediated by DNA methylation.

Girls with a History of Premature Adrenarche Have Advanced Growth and Pubertal Development at the Age of 12 Years

BACKGROUND

Premature adrenarche (PA) has been linked to early thelarche and menarche, but longitudinal data on growth and pubertal development after PA are insufficient.

METHODS

Growth and pubertal development of mostly full-term and appropriate for gestational age-born 43 PA (36 girls) and 63 control children (52 girls) were analyzed prospectively. Children examined first at the mean age of 7.6 years were reexamined at the mean age of 12.0 years.

RESULTS

The PA girls but not the boys were taller and had higher body mass index (BMI) than the controls. A higher proportion of the PA than control girls had reached menarche, while the same percentage of the PA and control boys were at Tanner genital stage ≥2. The PA girls with premature pubarche (PP) were taller but not heavier and had more often reached menarche by the age of 12 years than the PA girls without PP. The PA girls with menarche had lower birth length (BL) and higher prepubertal insulin-like growth factor 1 (IGF-1) concentrations compared with non-menarcheal PA girls. In logistic regression analyses for all girls, lower BL standard deviation score, earlier maternal menarche, and higher prepubertal IGF-1 were independently associated with menarche.

CONCLUSION

At 12 years of age, the PA girls had higher BMI, advanced linear growth, and accelerated pubertal development with earlier menarche than the control girls. The PA girls with PP were taller and had earlier menarche than the PA girls without PP. Lower BL and higher prepubertal IGF-1 concentration were predictive factors for menarche by the age of 12 years.

The Pathogenesis of Polycystic Ovary Syndrome (PCOS): The Hypothesis of PCOS as Functional Ovarian Hyperandrogenism Revisited

Polycystic ovary syndrome (PCOS) was hypothesized to result from functional ovarian hyperandrogenism (FOH) due to dysregulation of androgen secretion in 1989-1995. Subsequent studies have supported and amplified this hypothesis. When defined as otherwise unexplained hyperandrogenic oligoanovulation, two-thirds of PCOS cases have functionally typical FOH, characterized by 17-hydroxyprogesterone hyperresponsiveness to gonadotropin stimulation. Two-thirds of the remaining PCOS have FOH detectable by testosterone elevation after suppression of adrenal androgen production. About 3% of PCOS have a related isolated functional adrenal hyperandrogenism. The remaining PCOS cases are mild and lack evidence of steroid secretory abnormalities; most of these are obese, which we postulate to account for their atypical PCOS. Approximately half of normal women with polycystic ovarian morphology (PCOM) have subclinical FOH-related steroidogenic defects. Theca cells from polycystic ovaries of classic PCOS patients in long-term culture have an intrinsic steroidogenic dysregulation that can account for the steroidogenic abnormalities typical of FOH. These cells overexpress most steroidogenic enzymes, particularly cytochrome P450c17. Overexpression of a protein identified by genome-wide association screening, differentially expressed in normal and neoplastic development 1A.V2, in normal theca cells has reproduced this PCOS phenotype in vitro. A metabolic syndrome of obesity-related and/or intrinsic insulin resistance occurs in about half of PCOS patients, and the compensatory hyperinsulinism has tissue-selective effects, which include aggravation of hyperandrogenism. PCOS seems to arise as a complex trait that results from the interaction of diverse genetic and environmental factors. Heritable factors include PCOM, hyperandrogenemia, insulin resistance, and insulin secretory defects. Environmental factors include prenatal androgen exposure and poor fetal growth, whereas acquired obesity is a major postnatal factor. The variety of pathways involved and lack of a common thread attests to the multifactorial nature and heterogeneity of the syndrome. Further research into the fundamental basis of the disorder will be necessary to optimally correct androgen levels, ovulation, and metabolic homeostasis.

Serum insulin-like growth factor-1 levels in females and males in different cervical vertebral maturation stages

OBJECTIVE

The aim of this cross sectional study was to assess serum insulin-like growth factor-1 (IGF-1) levels in female and male subjects at various cervical vertebral maturation (CVM) stages.

MATERIAL AND METHODS

The study sample consisted of 60 subjects, 30 females and 30 males, in the age range of 8-23 years. For all subjects, serum IGF-1 level was estimated from blood samples by means of chemiluminescence immunoassay (CLIA). CVM was assessed on lateral cephalograms using the method described by Baccetti. Serum IGF-1 level and cervical staging data of 30 female subjects were included and taken from records of a previous study. Data were analyzed by Kruska-Wallis and Mann Whitney test. Bonferroni correction was carried out and alpha value was set at 0.003.

RESULTS

Peak value of serum IGF-1 was observed in cervical stages CS3 in females and CS4 in males. Differences between males and females were observed in mean values of IGF-1 at stages CS3, 4 and 5. The highest mean IGF-1 levels in males was observed in CS4 followed by CS5 and third highest in CS3; whereas in females the highest mean IGF-1 levelswas observed in CS3 followed by CS4 and third highest in CS5. Trends of IGF-1 in relation to the cervical stages also differed between males and females. The greatest mean serum IGF-1 value for both sexes was comparable, for females (397 ng/ml) values were slightly higher than in males (394.8 ng/ml).

CONCLUSIONS

Males and females showed differences in IGF-1 trends and levels at different cervical stages.

[Association between IGF system and PAPP-A in coronary atherosclerosis]

Atherosclerosis is a condition that involves multiple pathophysiological mechanisms and whose knowledge has not been fully elucidated. Often, scientific advances on the atherogenic pathophysiology generate that molecules not previously considered in the scene of this disease, were attributed actions on the onset or progression of it. A representative example is the study of a new mechanism involved in the atherogenic process, consisting of the association between the insulin-like growth factor (IGF) system and pregnancy-associated plasma protein-A (PAPP-A). Insulin-like growth factor system is a family of peptides that include 3 peptide hormones, 4 transmembrane receptors and 6 binding proteins. Insulin-like growth factor-1 (IGF-1) is the main ligand of the IGF system involved in coronary atherosclerosis. IGF-1 exerts its effects via activation of the IGF-1R receptor on vascular smooth muscle cells or macrophages. In vascular smooth muscle cells promotes migration and prevents apoptosis which increases plaque stability while in macrophages reduces reverse cholesterol transport leading to the formation of foam cells. Regulation of IGF-1 endothelial bioavailability is carried out by IGFBP proteases, mainly by PAPP-A. In this review, we address the mechanisms between IGF system and PAPP-A in atherosclerosis with emphasis on molecular effects on vascular smooth muscle cells and macrophages.

Prenatal caffeine exposure-induced adrenal developmental abnormality in male offspring rats and its possible intrauterine programming mechanisms

Glucocorticoid (GC) is a major factor for fetal tissue maturation and fate decision after birth. We previously demonstrated that prenatal caffeine exposure (PCE) suppressed fetal adrenal steroidogenesis and resulted in adrenal dysplasia. However, whether these changes play a role until adulthood and its intrauterine programming mechanisms remain unknown. In the present study, a rat model of intrauterine growth retardation (IUGR) was established by PCE, male fetuses and adult offspring were sacrificed at postnatal day (PD) 1, PD7, PD35, PD100 and PD168, respectively. Results showed that the PCE fetal weight decreased and the IUGR rate increased, while the serum corticosterone (CORT) level increased but the insulin-like growth factor 1 (IGF1) level decreased. Fetal adrenal exhibited an enhanced GC-activation system (11β-hydroxysteroid dehydrogenases/corticoid receptors/CCAAT/enhancer binding proteins), an inhibited IGF1 pathway and steroid synthesis function. After birth, the serum CORT levels in the PCE offspring were increased in the early period followed by falling in the later stage, while the serum IGF1 level change was the opposite and was accompanied by an obvious catch-up growth. Furthermore, the adrenal GC-activation system was inhibited but the IGF1 signaling pathway was enhanced, resulting in a compensatory increase of adrenal steroidogenesis, and the expression of steroidal synthetase was consistent with that of the IGF1 signaling pathway. Based on these findings, we proposed "two-programming mechanisms" for PCE-induced adrenal abnormality: the "first programming" mechanism is a lower function of adrenal steroidogenesis, and prenatal and postnatal adrenal structural and functional abnormalities triggered by the intrauterine GC-IGF1 axis programming-mediated by the GC-activation system that acts as "the second programming" mechanism.

Copy number variations alter methylation and parallel IGF2 overexpression in adrenal tumors

Overexpression of insulin growth factor 2 (IGF2) is a hallmark of adrenocortical carcinomas and pheochromocytomas. Previous studies investigating the IGF2/H19 locus have mainly focused on a single molecular level such as genomic alterations or altered DNA methylation levels and the causal changes underlying IGF2 overexpression are still not fully established. In the current study, we analyzed 62 tumors of the adrenal gland from patients with Conn's adenoma (CA, n=12), pheochromocytomas (PCC, n=10), adrenocortical benign tumors (ACBT, n=20), and adrenocortical carcinomas (ACC, n=20). Gene expression, somatic copy number variation of chr11p15.5, and DNA methylation status of three differential methylated regions of the IGF2/H19 locus including the H19 imprinting control region were integratively analyzed. IGF2 overexpression was found in 85% of the ACCs and 100% of the PCCs compared to 23% observed in CAs and ACBTs. Copy number aberrations of chr11p15.5 were abundant in both PCCs and ACCs but while PCCs retained a diploid state, ACCs were frequently tetraploid (7/19). Loss of either a single allele or loss of two alleles of the same parental origin in tetraploid samples resulted in a uniparental disomy-like genotype. These copy number changes correlated with hypermethylation of the H19 ICR suggesting that the lost alleles were the unmethylated maternal alleles. Our data provide conclusive evidence that loss of the maternal allele correlates with IGF2 overexpression in adrenal tumors and that hypermethylation of the H19 ICR is a consequence thereof.

Adrenocortical growth and cancer

The adrenal gland consists of two distinct parts, the cortex and the medulla. Molecular mechanisms controlling differentiation and growth of the adrenal gland have been studied in detail using mouse models. Knowledge also came from investigations of genetic disorders altering adrenal development and/or function. During embryonic development, the adrenal cortex acquires a structural and functional zonation in which the adrenal cortex is divided into three different steroidogenic zones. Significant progress has been made in understanding adrenal zonation. Recent lineage tracing experiments have accumulated evidence for a centripetal differentiation of adrenocortical cells from the subcapsular area to the inner part of the adrenal cortex. Understanding of the mechanism of adrenocortical cancer (ACC) development was stimulated by knowledge of adrenal gland development. ACC is a rare cancer with a very poor overall prognosis. Abnormal activation of the Wnt/β-catenin as well as the IGF2 signaling plays an important role in ACC development. Studies examining rare genetic syndromes responsible for familial ACT have played an important role in identifying genetic alterations in these tumors (like TP53 or CTNNB1 mutations as well as IGF2 overexpression). Recently, genomic analyses of ACT have shown gene expression profiles associated with malignancy as well as chromosomal and methylation alterations in ACT and exome sequencing allowed to describe the mutational landscape of these tumors. This progress leads to a new classification of these tumors, opening new perspectives for the diagnosis and prognostication of ACT. This review summarizes current knowledge of adrenocortical development, growth, and tumorigenesis.

Obesity is positively associated with dehydroepiandrosterone sulfate concentrations at 7 y in Chilean children of normal birth weight

BACKGROUND

In low-birth-weight girls, obesity increases the risk of premature adrenarche and metabolic complications. However, the consistency of this association in normal-birth-weight children and its potential mediators remain unknown.

OBJECTIVES

The objectives were to assess the associations between obesity indicators and dehydroepiandrosterone sulfate (DHEAS) at 7 y of age and to evaluate the role of hormonal markers on these associations.

DESIGN

We assessed in 969 participants (6.9 y; 48% girls; all Tanner I) in the Growth and Obesity Chilean Cohort Study the associations between DHEAS and weight, BMI, waist circumference (WC), waist-to-height ratio, skinfold thickness, and percentage total fat (bioimpedance) and determined whether these associations were related to insulin, insulin-like growth factor I (IGF-I), and leptin. We also compared BMI and height growth from 0 to 7 y of age in nonobese and obese children with normal and high DHEAS (≥75th percentile) at 7 y.

RESULTS

DHEAS concentrations were similar between girls (30.3 ±1.86 μg/dL) and boys (29.4 ±1.73 μg/dL) (P > 0.05); 17.3% of children were obese (BMI-for-age z score ≥2 SD). Adiposity indicators were positively and similarly associated with DHEAS [ie, BMI, β standardized regression coefficient: 0.23 (95% CI: 0.17, 0.29); WC, β standardized regression coefficient: 0.23 (95% CI: 0.16, 0.30)]; these associations were only partially related to IGF-I and leptin. Obese children had twice the risk of high DHEAS (OR: 2.16; 95% CI: 1.51, 3.09); at 7 y, obese children with high DHEAS were fatter and more centrally obese than their counterparts (P < 0.05), although their previous growth was similar (P > 0.05). None of the results differed by sex (P > 0.05).

CONCLUSION

In children of normal birth weight, obesity is positively associated with DHEAS at 7 y of age.

Adrenal cytomegaly is a frequent pathologic finding in hemoglobin bart hydrops fetalis

Adrenocortical cytomegaly (AC) is a relatively uncommon phenomenon but tends to occur in certain situations, including specific congenital anomalies and hydrops due to maternal-fetal Rhesus incompatibility. Because the pathology in the latter condition does not differ greatly from hemoglobin (Hb) Bart hydrops fetalis, we performed a retrospective review of fetal and perinatal autopsy cases with Hb Bart to determine the prevalence of AC in that condition. Over a 10-year period (2001-2010) at King Chulalongkorn Memorial Hospital, there were 16 hydropic cases confirmed to have Hb Bart. Adrenocortical cytomegaly was found in 13 cases (81%). For comparison, we determined the occurrence of AC in cases of hydrops fetalis not due to Hb Bart (n  =  33) and a heterogeneous group of congenital anomalies (n  =  34). Adrenocortical cytomegaly was identified in only 1 case of Beckwith-Wiedemann syndrome and 2 cases of anencephaly. Thus, AC is a common finding in cases of Hb Bart, a finding not previously documented. Moreover, our study suggests that Hb Bart is one of the conditions most commonly associated with AC. The reasons for this are not known. The mean Hb levels for the hydrops cases with Hb Bart and those with other forms of anemia showed no significant difference (P  =  0.63), nor was there any significant difference in Hb levels between cases of Hb Bart with and without AC. Nonetheless, the consistency of AC in cases of Hb Bart suggests that further study of this particular group of patients might shed light on the pathogenesis of this poorly understood pathologic finding.

Adrenocortical stem and progenitor cells: implications for adrenocortical carcinoma

The continuous centripetal repopulation of the adrenal cortex is consistent with a population of cells endowed with the stem/progenitor cell properties of self-renewal and pluripotency. The adrenocortical capsule and underlying undifferentiated cortical cells are emerging as critical components of the stem/progenitor cell niche. Recent genetic analysis has identified various signaling pathways including Sonic Hedgehog (Shh) and Wnt as crucial mediators of adrenocortical lineage and organ homeostasis. Shh expression is restricted to the peripheral cortical cells that express a paucity of steroidogenic genes but give rise to the underlying differentiated cells of the cortex. Wnt/β-catenin signaling maintains the undifferentiated state and adrenal fate of adrenocortical stem/progenitor cells, in part through induction of its target genes Dax1 and inhibin-α, respectively. The pathogenesis of ACC, a rare yet highly aggressive cancer with an extremely poor prognosis, is slowly emerging from studies of the stem/progenitor cells of the adrenal cortex coupled with the genetics of familial syndromes in which ACC occurs. The frequent observation of constitutive activation of Wnt signaling due to loss-of-function mutations in the tumor suppressor gene APC or gain-of-function mutation in β-catenin in both adenomas and carcinomas, suggests perhaps that the Wnt pathway serves an early or initiating insult in the oncogenic process. Loss of p53 might be predicted to cooperate with additional genetic insults such as IGF2 as both are the most common genetic abnormalities in malignant versus benign adrenocortical neoplasms. It is unclear whether other factors such as Pod1 and Pref1, which are implicated in stem/progenitor cell biology in the adrenal and/or other organs, are also implicated in the etiology of adrenocortical carcinoma. The rarity and heterogeneous presentation of ACC makes it difficult to identify the cellular origin and the molecular progression to cancer. A more complete understanding of adrenocortical stem/progenitor cell biology will invariably aid in characterization of the molecular details of ACC tumorigenesis and may offer new options for therapeutic intervention.

IGF-I-IGFBP-3-acid-labile subunit (ALS) complex in children and adolescents with classical congenital adrenal hyperplasia due to 21-hydroxylase deficiency (CAH)

It has been shown that changes in IGF-I and IGFBP levels in children with classical congenital adrenal hyperplasia due to 21-hydroxylase deficiency (CAH) are correlated with different states of metabolic control. Our approach was to analyze the serum levels of IGF-I, IGFBP-3, their molar ratio IGF-I:IGFBP-3 (MR), and ALS in a cohort of CAH children and adolescents, and their associations with different clinical and biochemical parameters.

DESIGN AND PATIENTS

56 patients, aged between 5.6 and 19.0 years were studied cross-sectionally. All patients had genetically proven CAH and received standard steroid substitution therapy. We measured serum levels of IGF-I, IGFBP-3, and ALS by commercial ELISA and calculated MR and assigned population-based SD scores (SDS).

RESULTS

(median, quartiles) Overall IGF-I was not significantly altered (0.05 SDS, -1.21, 0.92), whereas IGFBP-3 was significantly elevated (1.50 SDS; 0.58, 1.95, p<0.0001) compared to the reference population. Consecutively, MR was decreased (-0.64 SDS; -1.38, 0.32; p=0.0017). ALS was clearly decreased (-1.95 SDS; -3.075, -1.00; p<0.0001). ALS, IGF-I, MR, and IGFBP-3 SDS were lower in pubertal than in prepubertal patients (p<0.05). ALS SDS were lower in girls (p=0.0038). Correlation analyses (r(s), p) revealed correlations between MR/ALS and chronological age (-0.583, <0.0001/-0.428, 0.0010), MR/ALS and Tanner stages (-0.500, <0.0001/-0.334, 0.0118), MR/ALS and bone age (0.407, 0.0075/0.426, 0.0049), and between MR and ALS (0.405, 0.0020), respectively. For MR and ALS, we found no significant correlations for BMI, HOMA-IR, hydrocortisone and fludrocortisone dosage, or parameters of metabolic control.

CONCLUSIONS

Our data provide evidence that the components of the trimeric IGF-I-IGFBP-3-ALS complex are altered in CAH children with possible implications on pubertal growth and final height.

Body fat and animal protein intakes are associated with adrenal androgen secretion in children

BACKGROUND

Adrenarche is the increase in adrenal androgen (AA) production starting in childhood. Until now, it has been unknown whether or not nutritional factors modulate adrenarche.

OBJECTIVE

The objective was to examine whether body composition and certain dietary intakes are associated with AA production in children after accounting for urinary indicators of major adrenarche-related steroidogenic enzymes.

DESIGN

Androgen and glucocorticoid metabolites were profiled by gas chromatography-mass spectrometry in 24-h urine samples of 137 healthy prepubertal children aged 3-12 y, for whom birth characteristics, growth velocity data, and 3-d weighed-diet record information were available. Associations of the sum of C19 metabolites (reflecting daily AA secretion) with nutritional factors [fat mass (FM), fat-free mass (FFM), nutrient intakes, glycemic index, and glycemic load] and AA-relevant estimates of steroidogenic enzyme were examined in stepwise multiple regression models adjusted for age, sex, urine volume, and total energy intake. Enzyme activity estimates were calculated by using specific urinary steroid metabolite ratios.

RESULTS

Of the nutrition-relevant predictors, FM (P < 0.0001) explained most of the variation of AA secretion (R(2) = 5%). Animal protein intake was also positively associated with AA secretion (P < 0.05), which explained 1% of its variation. FFM (P = 0.1) and total protein intake (P = 0.05) showed positive trends. The difference in daily AA secretion between the lowest and highest quartile of FM was comparable to that between the lowest and highest estimated activity of one of the major steroidogenic enzymes.

CONCLUSIONS

Body fat mass may relevantly influence prepubertal adrenarchal androgen status. In addition, animal protein intake may also make a small contribution to AA secretion in children.

Expression of estrogen receptor GPR30 in the rat spinal cord and in autonomic and sensory ganglia

The G protein-coupled receptor GPR30 has recently been identified as a nonnuclear estrogen receptor. Reverse transcriptase-polymerase chain reaction revealed expression of GPR30 mRNA in varying quantities in the rat spinal cord, dorsal root ganglia, nodose ganglia, trigeminal ganglia, hippocampus, brain stem, and hypothalamus. Immunohistochemical studies that used a rabbit polyclonal antiserum against the human GPR30 C-terminus revealed a fine network of GPR30-immunoreactive (irGPR30) cell processes in the superficial layers of the spinal cord; some of which extended into deeper laminae. A population of neurons in the dorsal horn and ventral horn were irGPR30. Dorsal root, nodose, and trigeminal ganglionic neurons displayed varying intensities of irGPR30. Positively labeled neurons were detected in the major pelvic ganglion, but not in the superior cervical ganglion. A population of chromaffin cells in the adrenal medulla was irGPR30, so were cells of the zona glomerulosa. Double-labeling the adrenal medulla with GPR30 antiserum and tyrosine hydroxylase antibody or phenylethanolamine-N-methyltransferase antiserum revealed that irGPR30 is expressed in the majority of tyrosine hydroxylase-positive chromaffin cells. Last, some of the myenteric ganglion cells were irGPR30. Tissues processed with preimmune serum resulted in no staining. Voltage-sensitive dye imaging studies showed that the selective GPR30 agonist G-1 (1, 10, and 100 nM) depolarized cultured spinal neurons in a concentration-dependent manner. Collectively, our result provides the first evidence that GPR30 is expressed in neurons of the dorsal and ventral horn as well as in sensory and autonomic neurons, and activation of GPR30 by the selective agonist G-1 depolarizes cultured spinal neurons.

Expression of the IGF and the aromatase/estrogen receptor systems in human adrenal tissues from early infancy to late puberty: implications for the development of adrenarche

Adrenarche is a process of postnatal sexual maturation occurring in higher primates, in which there is an increase in the secretion of adrenal androgens. It is the consequence of a process of postnatal organogenesis characterized by the development of a new zone in the adrenal cortex, the zona reticularis (ZR). The mechanism of this phenomenon remains poorly understood, suggesting that it might be a multifactorial event. A relationship between circulating IGF-I, insulin sensitivity, and adrenal androgens has been postulated. Boys and girls have different patterns of changes in insulin sensitivity at puberty, perhaps secondary to differences in the estrogen milieu. Estrogen effects may also play a role in premature adrenarche. Peripheral or local IGF-1 actions could regulate adrenal progenitor cell proliferation and migration. Since adrenal progenitor cells as well as IGF-I and the IGF-R1 are located in the outer zone of the adrenal cortex during childhood and adolescence, this peripheral cell layer, below the capsule, may contain undifferentiated progenitor cells. Therefore, the IGF-R1 signaling pathway might positively modulate the proliferation and migration of adrenal progenitor cell to stimulate the development of adrenal zones, including ZR. However, no evidence of a direct action of IGF-I on ZR was found. In addition, a role for estrogens in the ontogenesis of ZR is suggested by the presence of aromatase (CYP19) in the subcapsular zona glomerulosa and in the adrenal medulla. Estrogens produced locally could act on ZR by interacting with estrogen receptor beta (ERbeta), but not alpha, and membrane estrogen receptor GPR-30. An estradiol-induced increase in DHEA/cortisol ratio was indeed seen in cultures of adrenocortical cells from post-adrenarche adrenals. In summary, several lines of evidence point to the action of multiple factors, such as local adrenal maturational changes and peripheral metabolic signals, on postnatal human adrenal gland ZR formation.

Milk--the promoter of chronic Western diseases

Common chronic diseases of Western societies, such as coronary heart disease, diabetes mellitus, cancer, hypertension, obesity, dementia, and allergic diseases are significantly influenced by dietary habits. Cow's milk and dairy products are nutritional staples in most Western societies. Milk and dairy product consumption is recommended by most nutritional societies because of their beneficial effects for calcium uptake and bone mineralization and as a source of valuable protein. However, the adverse long-term effects of milk and milk protein consumption on human health have been neglected. A hypothesis is presented, showing for the first time that milk protein consumption is an essential adverse environmental factor promoting most chronic diseases of Western societies. Milk protein consumption induces postprandial hyperinsulinaemia and shifts the growth hormone/insulin-like growth factor-1 (IGF-1) axis to permanently increased IGF-1 serum levels. Insulin/IGF-1 signalling is involved in the regulation of fetal growth, T-cell maturation in the thymus, linear growth, pathogenesis of acne, atherosclerosis, diabetes mellitus, obesity, cancer and neurodegenerative diseases, thus affecting most chronic diseases of Western societies. Of special concern is the possibility that milk intake during pregnancy adversely affects the early fetal programming of the IGF-1 axis which will influence health risks later in life. An accumulated body of evidence for the adverse effects of cow's milk consumption from fetal life to childhood, adolescence, adulthood and senescence will be provided which strengthens the presented hypothesis.

A possible role of insulin-like growth factor-II C-peptide in regulating the function of steroidogenic cells in adult frog adrenal glands

The sole structural determinant for the differential ability of the insulin-like growth factors (IGF-I and IGF-II) to induce autophosphorylation of specific insulin receptor (IR) tyrosine residues and activate downstream signaling molecules is the C domain. The IR is structurally related to the type I insulin-like growth factor receptor (IGF-IR). This study aimed to identify the presence of IGF receptors by which the IGF-II C-peptide could mediate its effects in the frog (Rana ridibunda) adrenal glands and to observe whether injection of IGF-II C-peptide affects the function of adrenal steroidogenic cells using light and transmission electron microscopy and by the evaluation of the immunoreactivity of steroidogenic acute regulatory protein (StAR). After IGF-II C-peptide injection, there was a reduction of StAR protein immunoreactivity levels, an accumulation of large lipid droplets in close contact with each other, and an induction of proliferation of the steroidogenic cells. These results indicate a possible role of IGF-II C-peptide in steroidogenic cell function and in induction of steroidogenesis. The detection in this study of IGF-I receptor (IGF-IR) immunoreactivity in frog adrenal glands also indicates that the metabolic and mitogenic effects of IGF-II C-peptide in these glands may occur via the IGF-IR.

Milk consumption: aggravating factor of acne and promoter of chronic diseases of Western societies

Consumption of cow's milk and cow's milk protein result in changes of the hormonal axis of insulin, growth hormone and insulin-like growth factor-1(IGF-1) in humans. Milk consumption raises IGF-1 serum levels in the perinatal period, adolescence and adulthood. During puberty with the physiological onset of increased secretion of growth hormone, IGF-1 serum levels increase and are further enhanced by milk consumption. IGF-1 is a potent mitogen; after binding to its receptor in various tissues, it induces cell proliferation and inhibits apoptosis. Keratinocytes and sebocytes, as well as the androgen-synthesizing adrenals and gonads, are stimulated by IGF-1. The epidemic incidence of adolescent acne in Western milk-consuming societies can be explained by the increased insulin- and IGF-1-stimulation of sebaceous glands mediated by milk consumption. Acne can be regarded as a model for chronic Western diseases with pathologically increased IGF-1-stimulation. Many other organs, such as the thymus, bones, all glands, and vascular smooth muscle cells as well as neurons are subject to this abnormally increased hormonal stimulation. The milk-induced change of the IGF-1-axis most likely contributes to the development of fetal macrosomia, induction of atopy, accelerated linear growth, atherosclerosis, carcinogenesis and neurodegenerative diseases. Observations of molecular biology are supported by epidemiologic data and unmask milk consumption as a promoter of chronic diseases of Western societies.

Identification and developmental changes of aromatase and estrogen receptor expression in prepubertal and pubertal human adrenal tissues

CONTEXT

The mechanisms of postnatal adrenal zonation remain unclear.

OBJECTIVE

To provide a clue for a possible role of estrogens in adrenarche, we studied the expression of estrogen receptor (ER)alpha, ERbeta, G protein-coupled receptor (GPR)30, and cP450aromatase (cP450arom) in human adrenal tissue.

DESIGN

Human adrenal tissue was collected from three postnatal age groups (Grs): Gr 1, younger than 3 months (n = 12), fetal zone involution; Gr 2, 3 months to 6 yr (n = 17), pre-adrenarche; and Gr 3, older than 6-20 yr (n = 12), post-adrenarche period.

RESULTS

ERbeta mRNA in Grs 1 and 3 was higher than in Gr 2 (P < 0.05). By immunohistochemistry and laser capture microdissection followed by RT-PCR, ERbeta was expressed in zona reticularis and fetal zone, GPR30 in zona glomerulosa (ZG) and adrenal medulla, while ERalpha mRNA and protein were undetectable. cP450arom mRNA in Gr 3 was higher than in Grs 1 and 2 (P < 0.05), and localized to ZG and adrenal medulla by laser capture microdissection. cP450arom Immunoreactivity was observed in adrenal medulla in the three Grs and in subcapsular ZG of Gr 3. Double-immunofluorescence studies revealed that cP450arom and chromogranin A only colocalize in adrenal medulla of subjects younger than 18 months. In these samples, exon 1.b-derived transcript was 3.5-fold higher, while exon 1.a-, 1.c-, and 1.d-derived transcripts were 3.3-, 1.9-, and 1.7-fold lower, respectively, than in subjects older than 6 yr.

CONCLUSIONS

Our results suggest that estrogens produced locally in adrenal medulla would play a role in zona reticularis functional differentiation through ERbeta. The cP450arom and GPR30 expression in subcapsular ZG, colocalizing with a high-cell proliferation index, previously reported, suggests a local GPR30-dependent estrogen action in proliferation and migration of progenitor adrenal cells.

Possible role of insulin-like growth factor-II C-peptide on catecholamine release and ultrastructural aspects of chromaffin cells in the adrenal gland of the frog

The present study was undertaken to demonstrate that insulin-like growth factor-II C-peptide (IGF-II C-peptide) affects the function of the adrenal gland of Rana ridibunda (Anura, Amphibia) by stimulating chromaffin cells. Previous studies have shown that insulin-like growth factors affect adrenal gland function in mammals. On the basis of these findings, frogs were injected with IGF-II C-peptide (2.5 microg/0.2 ml), whereas control animals were injected with Ringer solution (0.2 ml). The adrenal glands were removed at 12 and 48 h after injection and fixed, embedded in paraffin wax and Epon, and examined by immunohistochemistry and transmission electron microscopy to investigate whether there were structural changes and activation of chromaffin cells in the frog adrenal gland. Sections were stained with hematoxylin and eosin for overall tissue analysis and, in parallel, serotonin was localized using the streptavidin-biotin complex technique while dopamine beta-hydroxylase was shown by the peroxidase-antiperoxidase-3, 3'-diaminobenzidine tetrachloride method. After injection of IGF-II C-peptide, chromaffin cells released serotonin and synthesized dopamine beta-hydroxylase. The most pronounced effect of IGF-II C-peptide on the chromaffin cells was observed at 12h after injection. Our results indicate that there is a possible role of IGF-II C-peptide on chromaffin cell activity enhancing catecholamine release in the adrenal gland of the frog.