Kathleen E. Bethin

Pituitary-Adrenal Axis Regulation in Crh-Deficient Mice

Corticotropin-releasing hormone (CRH)-deficient (knockout (KO)) mice demonstrate severely impaired adrenal responses to restraint, ether, and fasting, and lack the normal diurnal glucocorticoid (GC) rhythm. Here, we summarize recent studies determining the role of CRH in augmenting plasma adrenocorticotrophic hormone (ACTH) concentration after glucocorticoid withdrawal and pituitary-adrenal axis stimulation in the context of inflammation. Even though GC insufficient, basal pituitary proopiomelanocortin (POMC) mRNA, ACTH peptide content within the pituitary, and plasma ACTH concentrations are not elevated in CRH KO mice. POMC mRNA content in CRH KO mice increases following adrenalectomy, and this increase is reversed by GC, but not aldosterone, replacement. In marked contrast to the increase in POMC mRNA, plasma ACTH does not increase in the CRH KO mice following adrenalectomy. Administration of CRH to adrenalectomized CRH KO mice results in acute, robust ACTH secretion. Thus, loss of GC feedback can increase POMC gene expression in the pituitary, but CRH action is essential for increased secretion of ACTH into the circulation. While GC secretion is impaired in CRH KO mice after most stimuli, we have found near-normal GC responses to inflammation and systemic immune challenge. Studies in mice with CRH and IL-6 deficiency reveal that IL-6 is essential for activation of the pituitary-adrenal axis during inflammatory and other stressors in the absence of CRH.

Intranasal Glucagon for Treatment of Insulin-Induced Hypoglycemia in Adults With Type 1 Diabetes: A Randomized Crossover Noninferiority Study

OBJECTIVE Treatment of severe hypoglycemia with loss of consciousness or seizure outside of the hospital setting is presently limited to intramuscular glucagon requiring reconstitution immediately prior to injection, a process prone to error or omission. A needle-free intranasal glucagon preparation was compared with intramuscular glucagon for treatment of insulin-induced hypoglycemia. RESEARCH DESIGN AND METHODS At eight clinical centers, a randomized crossover noninferiority trial was conducted involving 75 adults with type 1 diabetes (mean age, 33 ± 12 years; median diabetes duration, 18 years) to compare intranasal (3 mg) versus intramuscular (1 mg) glucagon for treatment of hypoglycemia induced by intravenous insulin. Success was defined as an increase in plasma glucose to ≥70 mg/dL or ≥20 mg/dL from the glucose nadir within 30 min after receiving glucagon. RESULTS Mean plasma glucose at time of glucagon administration was 48 ± 8 and 49 ± 8 mg/dL at the intranasal and intramuscular visits, respectively. Success criteria were met at all but one intranasal visit and at all intramuscular visits (98.7% vs. 100%; difference 1.3%, upper end of 1-sided 97.5% CI 4.0%). Mean time to success was 16 min for intranasal and 13 min for intramuscular (P < 0.001). Head/facial discomfort was reported during 25% of intranasal and 9% of intramuscular dosing visits; nausea (with or without vomiting) occurred with 35% and 38% of visits, respectively. CONCLUSIONS Intranasal glucagon was highly effective in treating insulin-induced hypoglycemia in adults with type 1 diabetes. Although the trial was conducted in a controlled setting, the results are applicable to real-world management of severe hypoglycemia, which occurs owing to excessive therapeutic insulin relative to the impaired or absent endogenous glucagon response.

Glucagon Nasal Powder: A Promising Alternative to Intramuscular Glucagon in Youth With Type 1 Diabetes

OBJECTIVE Treatment of severe hypoglycemia outside of the hospital setting is limited to intramuscular glucagon requiring reconstitution prior to injection. The current study examined the safety and dose-response relationships of a needle-free intranasal glucagon preparation in youth aged 4 to <17 years. RESEARCH DESIGN AND METHODS A total of 48 youth with type 1 diabetes completed the study at seven clinical centers. Participants in the two youngest cohorts (4 to <8 and 8 to <12 years old) were randomly assigned to receive either 2 or 3 mg intranasal glucagon in two separate sessions or to receive a single, weight-based dose of intramuscular glucagon. Participants aged 12 to <17 years received 1 mg intramuscular glucagon in one session and 3 mg intranasal glucagon in the other session. Glucagon was given after glucose was lowered to <80 mg/dL (mean nadir ranged between 67 and 75 mg/dL). RESULTS All 24 intramuscular and 58 of the 59 intranasal doses produced a ≥25 mg/dL rise in glucose from nadir within 20 min of dosing. Times to peak plasma glucose and glucagon levels were similar under both intramuscular and intranasal conditions. Transient nausea occurred in 67% of intramuscular sessions versus 42% of intranasal sessions (P = 0.05); the efficacy and safety of the 2- and 3-mg intranasal doses were similar in the youngest cohorts. CONCLUSIONS Results of this phase 1, pharmacokinetic, and pharmacodynamic study support the potential efficacy of a needle-free glucagon nasal powder delivery system for treatment of hypoglycemia in youth with type 1 diabetes. Given the similar frequency and transient nature of adverse effects of the 2- and 3-mg intranasal doses in the two youngest cohorts, a single 3-mg intranasal dose appears to be appropriate for use across the entire 4- to <17-year age range.

Expanding Treatment Options for Youth With Type 2 Diabetes: Current Problems and Proposed Solutions: A White Paper From the NICHD Diabetes Working Group.

The Best Pharmaceuticals for Children Act of 2002 mandated that the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) carries out critical reviews of the gaps in knowledge and unmet needs regarding safe and effective pharmacologic treatment of infants, children, and adolescents in a broad range of disease areas. In 2012, NICHD selected diabetes mellitus as one of the pediatric disorders for review. Dr. William V. Tamborlane was named chair, and Dr. Linda DiMeglio, vice-chair, of the Diabetes Working Group. Together with Dr. George Giacoia of NICHD, they assembled a distinguished group of medical experts in childhood diabetes, including clinicians/clinical investigators from leading academic centers and from industry and representatives from the U.S. Food and Drug Administration (FDA), the European Medicines Agency (EMA), and the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), to carry out this review. It is very important to note that the views expressed in this article, as well as in other reports from the Diabetes Working Group, are the personal views of the authors and may not be understood or quoted as being made on behalf of or reflecting the position of the FDA or EMA or any of the organizations or pharmaceutical companies represented in our working group. As shown in Supplementary Table 1, the large Diabetes Working Group was divided into five committees: Type 1 Diabetes (T1D): Therapeutics, Type 2 Diabetes (T2D): Therapeutics, T1D: Natural History and Biomarkers, T2D: Natural History and Biomarkers, and Diabetes Pharmacology. The consensus of the T2D Therapeutics Committee was that its efforts should address the crisis in care that clinicians face in treating this disorder in adolescents. Despite a plethora of new drug classes and new agents within each class that have been approved for use in adults with T2D, in …

Dissecting Adrenal and Behavioral Responses to Stress by Targeted Gene Inactivation in Mice

To define the molecular pathways modulating adrenal and behavioral responses to stress, we have generated mice with inactivation of hypothalamic neuropeptides and signaling pathways. Studies in mice deficient in corticotropin-releasing hormone (CRH) have revealed the essential role for CRH in adrenal glucocorticoid production in response to many physiological and psychological stressors. Immune system activation in CRH-deficient mice provides a unique exception to the necessity for CRH in stimulating adrenal glucocorticoid production. By analyzing mice deficient in interleukin-6 (IL-6) and CRH, we find that restoration of glucocorticoid output with inflammation is largely mediated by dysregulated IL-6 production. Current studies focus on identifying cellular and gene targets by which glucocorticoids regulate immune system function. In contrast to impaired adrenocortical responses to stress, CRH-deficient mice exhibit normal behavioral responses to stress. To determine signaling pathways that may contribute to the behavioral responses to stress, we have generated and analyzed mice deficient in adenylyl cyclase type 8 (AC8). AC8 deficient mice have intact adrenocortical responses to stress, but an inability to undergo stress-induced alterations in behavior.

Identification of 9 uterine genes that are regulated during mouse pregnancy and exhibit abnormal levels in the cyclooxygenase-1 knockout mouse

BackgroundPreterm birth is the leading cause of all infant mortality. In 2004, 12.5% of all births were preterm. In order to understand preterm labor, we must first understand normal labor. Since many of the myometrial changes that occur during pregnancy are similar in mice and humans and mouse gestation is short, we have studied the uterine genes that change in the mouse during pregnancy. Here, we used microarray analysis to identify uterine genes in the gravid mouse that are differentially regulated in the cyclooxygenase-1 knockout mouse model of delayed parturition.MethodsGestational d18.0 uteri (n = 4) were collected from pregnant wild-type and cyclooxygenase-1 knockout mice. Part of the uterus was used for frozen sections and RNA was isolated from the remainder. Microarray analysis was performed at the Indiana University School of Medicine Genomic Core and analyzed using the Microarray Data Portal. Northern analysis was performed to confirm microarray data and the genes localized in the gravid uterus by in situ hybridization.ResultsWe identified 277 genes that are abnormally expressed in the gravid d18.0 cyclooxygenase-1 knockout mouse. Nine of these genes are also regulated in the normal murine uterus during the last half of gestation. Many of these genes are involved in the immune response, consistent with an important role of the immune system in parturition. Expression of 4 of these genes; arginase I, IgJ, Tnfrsf9 and troponin; was confirmed by Northern analysis to be mis-regulated during pregnancy in the knockout mouse. In situ hybridization of these genes demonstrated a similar location in the gravid wild-type and Cox-1 knockout mouse uteri.ConclusionTo our knowledge, this is the first work to demonstrate the uterine location of these 4 genes in the mouse during late pregnancy. There are several putative transcription factor binding sites that are shared by many of the 9 genes identified here including; estrogen and progesterone response elements and Ets binding sites. In summary, this work identifies 9 uterine murine genes that may play a role in parturition. The function of these genes is consistent with an important role of the immune system in parturition.

Response to Comment on Rickels et al. Intranasal Glucagon for Treatment of Insulin-Induced Hypoglycemia in Adults With Type 1 Diabetes: A Randomized Crossover Noninferiority Study. Diabetes Care 2016;39:264-270.

We thank Munoz et al. (1) for the opportunity to provide additional rationale for the study design and interpretation of the data supporting the noninferiority of intranasal glucagon for treatment of insulin-induced hypoglycemia. Our study (2) was not designed to test recovery from severe hypoglycemia but rather recovery from insulin-induced hypoglycemia that ethically may only be produced under the controlled conditions available in a clinical research center. Intranasal glucagon was effective in correcting insulin-induced hypoglycemia, and when considering only those subjects with nadir glucose concentrations <50 mg/dL, the average time to achieving a glucose concentration of 70 mg/dL or a 20 mg/dL increase was 16 min compared with 13 min with intramuscular glucagon (2). We make no claims that intranasal glucagon and intramuscular glucagon are “equally” effective. The noninferiority margin of 10% was chosen on the basis of the data for glucagon injection in a simulated emergency study where 10% of participants (parents of children and adolescents with type 1 diabetes) entirely failed to administer the injectable glucagon product (3). Despite …

Barriers to participation in industry-sponsored clinical trials in pediatric type 2 diabetes

The rapid emergence of type 2 diabetes (T2D) in the pediatric population has left pediatric endocrinologists with limited artillery in terms of management. While multiple medications are available for adults, Food and Drug Administration (FDA)‐approved medications in children are limited to only metformin and insulin. Additional treatment options require randomized controlled trials, yet heretofore several barriers at the participant and institutional level have impeded these studies from proceeding in children and adolescents. Identification of the most challenging obstacles that pediatric endocrinologists experience in participating in industry‐sponsored T2D trials may facilitate development of feasible platforms for future studies.

Etiology of gonadotropin-dependent precocious puberty

Precocious puberty is puberty occurring earlier than 2.5 SD below the mean. In boys, this is before age 9. In girls, the age is controversial, but classically, has been considered age 8 for white girls and 7 for African American girls. Precocious Puberty can be centrally or peripherally mediated and is more common in girls than boys. In central precocious puberty (CPP) the concern is to identify whether the etiology is pathological or idiopathic. In girls, the cause of CPP is usually idiopathic but in boys a central lesion is more common. The most commonly identified cause of CPP is the hypothalamic hamartoma. A head MRI should be considered in any child with CPP to rule out occult intracranial lesions.

Role of the GH/IGF-I axis in the growth retardation of weaver mice

IGF-I is a well-established anabolic growth factor essential for growth and development. Although the role of the GH/IGF-I axis is established for normal postnatal growth, its functional state in neurodegenerative diseases is not fully characterized. The weaver mutant mouse is a commonly used model for studying hereditary cerebellar ataxia and provides an opportunity to investigate the function of IGF-I in postnatal growth following neurodegeneration. Previously, we reported that weaver mice are growth retarded and their body weights correlate with a decrease in circulating IGF-I levels. Because weaver mice have the same food intake/body weight ratios as their wild type littermates, our observation suggests that an impairment of the GH/IGF-I axis, rather than poor nutrition, likely contributes to their growth retardation. This study further investigated the etiology of reduced circulating IGF-I levels. We found that GH levels in weaver mice were reduced following acute insulin injection, but the hepatic GH receptor transduction pathway signaled normally as evidenced by increased STAT5b phosphorylation and IGF-I mRNA levels in response to acute GH administration. In addition, 2-week GH treatment induced a significant increase in body weight and circulating IGF-I levels in homozygous weaver mice but not in wild type littermates. In summary, a deficiency in the GH/IGF-I axis may be partially responsible for postnatal growth retardation in weaver mutant mice. This deficiency may occur at the level of the pituitary and/or hypothalamus and can be improved with GH administration.