G-protein-coupled receptors (GPCRs) constitute an immensely important class of drug targets with diverse clinical applications. There are still more than 120 orphan GPCRs whose cognate ligands and physiological functions are not known. A set of circadian pacemaker neurons that governs daily rhythms in behavior and physiology resides in the suprachiasmatic nucleus (SCN) in the brain. Malfunction of the circadian clock has been linked to a multitude of diseases, such as sleeping disorders, obesity, diabetes, cardiovascular diseases, and cancer, which makes the clock an attractive target for drug development. Here, we review a recently identified role of Gpr176 in the SCN. Gpr176 is an SCN-enriched orphan GPCR that sets the pace of the circadian clock in the SCN. Even without known ligand, this orphan receptor has an agonist-independent basal activity to reduce cAMP signaling. A unique cAMP-repressing G-protein subclass Gz is required for the activity of Gpr176. We also provide an overview on the circadian regulation of G-protein signaling, with an emphasis on a role for the regulator of G-protein signaling 16 (RGS16). RGS16 is indispensable for the circadian regulation of cAMP in the SCN. Developing drugs that target the SCN remains an unfulfilled opportunity for the circadian pharmacology. This review argues for the potential impact of focusing on GPCRs in the SCN for the purpose of tuning the body clock.
Vitamin D is a modulator of both the innate and adaptive immune system. As vitamin D deficiency was a risk factor for some autoimmune diseases, we aimed to evaluate the serum vitamin D levels in autoimmune thyroid diseases (AITD) including Graves’ disease (GD) and Hashimoto’s thyroiditis (HT) and investigated the association between serum vitamin D levels and AITD. 175 AITD patients including 51 GD, 61 euthyroid HT (mild HT), 63 euthyroid HT patients with hypothyroidism receiving hormone therapy (treated HT) were recruited from the outpatient department. 51 controls were from the physical checkup center of the hospital. 25-Hydroxyvitamin D levels, thyroid function, antithyroid antibodies, IL-4, IL-17, and TNF-α were determined. Compared with the controls, treated and mild HT patients had significantly lower 25(OH)D levels (45.77±3.48 vs. 83.49±6.24 nmol/L, p<0.001) and (55.25±3.88 vs. 83.49±6.24 nmol/L, p<0.001), respectively. However, GD patients had similar 25(OH)D levels (81.77±5.60 vs. 83.49±6.24 nmol/L, p=0.808). Compared to 24.1% controls with prevalent vitamin D deficiency, mild HT and treated HT patients were significantly different (55.4%, p<0.001) and (70.3%, p<0.001), respectively; no difference was seen in the GD patients (22.9%, p=0.797). Serum 25(OH)D levels were not associated with thyroid function, antithyroid antibodies, and serum cytokines IL-4, IL-17, and TNF-α in patients with AITD. We observed relatively low vitamin D level in mild and treated HT patients, while GD patients had similar 25(OH)D levels to those of healthy individuals. Further studies are imperative to explore the complex etiology of vitamin D deficiency in AITD.
Vitamin D-dependent rickets type 2A (VDDR2A) is a rare inherited disorder with decreased tissue responsiveness to 1,25-dihydroxyvitamin D [1,25(OH)2D], caused by loss of function mutations in the vitamin D receptor (VDR) gene. Approximately 50 types of mutations have been identified so far that change amino acids in either the N-terminal DNA binding domain (DBD) or the C-terminal ligand binding domain (LBD) of the VDR protein. The degree of responsiveness to 1,25(OH)2D varies between patients with VDDR2A, which may depend on their residual VDR function. In this report, we describe a female patient with VDDR2A caused by an early stop codon (R30X) in the VDR gene that resulted in a severely truncated VDR protein. She developed alopecia and bowed legs within a year after birth and was diagnosed with rickets at the age of 2. She had been treated with active vitamin D and oral calcium supplementation until 22 years of age, when she developed secondary hyperparathyroidism and high bone turnover. The genetic diagnosis of VDDR2A promoted the discontinuation of active vitamin D treatment in favor of monotherapy with oral calcium supplementation. We observed amelioration of the secondary hyperparathyroidism and normalization of bone metabolic parameters within 6 years.
Prenatal undernutrition and postnatal overnutrition increase the risk of some peripheral and central metabolic disorders in adulthood. We speculated that disturbances of appetite/metabolic regulatory factors might already have been established in the early stages of life and contribute to obesity later in life. The effects of a high-fat diet on the levels of peripheral and central appetite/metabolic regulatory factors were compared between the offspring of normally nourished dams and those of undernourished dams in the peri-pubertal period. In the offspring of the normally nourished dams (control), the consumption of the high-fat diet resulted in lower hypothalamic mRNA levels of orexigenic factors (neuropeptide Y (NPY) and prepro-orexin (pporexin)), whereas no such changes were seen in the offspring of the undernourished dams (subjected to intrauterine growth restriction). These results indicate that in high-energy conditions either the adaptive response does not function properly or has not been established in the offspring of undernourished dams. Because NPY and pporexin are negatively regulated by leptin, these findings suggest that in the intrauterine growth restriction group, the leptin resistance of hypothalamic functions, which is usually caused by diet-induced obesity in adulthood, had already been established in the peri-pubertal period.
Uridine diphosphate-glucuronosyltransferase 2B15 (UGT2B15) conjugates 5α-androstane-3α, 17β-diol (3α-diol) to 3α-diol glucuronide (3α-diol G) in steroid target tissues. The present study investigated the regulation of UGT2B15 expression during the ovulatory process in the rat. Real-time PCR analysis revealed that treatment of immature rats with equine chorionic gonadotropin followed by human chorionic gonadotropin transiently stimulated UGT2B15 gene expression in granulosa cells of preovulatory follicles within 6 h. The progesterone receptor antagonist RU486 suppressed the gonadotropin-induced UGT2B15 expression. The expression of UGT2B15 and the levels of 3α-diol G were transiently increased by luteinizing hormone (LH) treatment in cultured preovulatory follicles. The LH-stimulated UGT2B15 mRNA level in cultured preovulatory follicles was inhibited by inhibitors of adenylyl cyclase, phosphoinositide 3-kinase and mitogen-activated protein kinase. Furthermore, a vitamin D receptor agonist (calcitriol) suppressed the LH-stimulated UGT2B15 expression in a dose-dependent manner. Taken together, these results indicate that gonadotropins transiently stimulate UGT2B15 expression and activity in preovulatory follicles, and UGT2B15 mRNA levels are regulated by the progesterone receptor and vitamin D receptor.
Metabolic disorders, such as PCOS (polycystic ovarian syndrome) and T2DM (type 2 diabetes mellitus), are associated with menstrual dysfunction, anovulation, infertility, and early pregnancy loss. Ovarian dysfunction is not only related to low pregnancy rates but also to the increased risk of miscarriage. Women with PCOS or T2DM, characterized by hyperinsulinemia, commonly experience ovarian dysfunction. In this study, we first explored whether high insulin levels directly affected ovarian functioning during embryo implantation. Mice in the insulin-treated group were given a subcutaneous injection of human recombinant insulin. After insulin treatment, serum levels of E2 (estrogen), PROG (progesterone), LH (luteinizing hormone), and FSH (follicle-stimulating hormone) were obviously lower, and there was a significant decrement of ovarian GDF9 (growth differentiation factor 9) mRNA. H&E (hematoxylin and eosin) staining showed a greater number of immature follicles and less luteinization in the insulin group. Further autophagy was studied in this process. A significant increase of P62 (SQSTM1/Sequestosome1) and a decrease of Cathepsin B, BECN1 (Beclin 1), and ULK1 (Unc-51-like kinase 1) mRNA in ovary was found in the insulin group. Western blot analysis showed that the expressions of LC3 (microtubule-associated protein 1 light chain 3), BECN1, and Cathepsin B proteins in ovaries from insulin group were obviously reduced, while P62 proteins were significantly increased. All these results illustrated that insulin could directly impair ovarian function during embryo implantation and the imbalance of ovarian autophagy due to insulin. Autophagy could enhance the impaired ovarian function results from insulin.
Patients with aldosterone-producing adenomas are treated using surgery, and patients with idiopathic hyperaldosteronism receive medical treatment using mineralocorticoid receptor antagonists (MRAs). However, the outcomes of surgical and medical treatment for primary aldosteronism (PA) remain unclear. Therefore, we compared the outcomes of surgical and medical treatment for PA and aimed to identify a specific subgroup that might benefit from medical treatment. We identified 269 patients who were treated for PA (unilateral excess: 221 cases; bilateral excess: 48 cases) during 2000-2015 at the Seoul National University Hospital and two other tertiary centers. The main outcomes were the amelioration of hypertension and hypokalemia. Treatment improved hypertension in the surgical treatment group (78.2%) and the medical treatment group (55.6%) (p = 0.001). At the last follow-up, hypokalemia was normalized in the surgical treatment group (97.1%) and the medical treatment group (93.7%, p = 0.046). Among patients with unilateral aldosterone excess, surgery provided advantages in resolving hypertension without worsening renal function. Among patients who were >60 years old or had impaired renal function, surgical and medical treatment provided similar amelioration of hypokalemia and hypertension. Three patients developed hyperkalemia after surgery, and no patients developed hyperkalemia after initiating medical treatment. The surgical treatment group exhibited a lower postoperative estimated glomerular filtration rate (eGFR) and higher serum potassium levels, compared to the medical treatment group. Surgical treatment provided better hypertension and hypokalemia outcomes among patients with PA, compared to medical treatment. However, MRAs may be appropriate for elderly patients with impaired renal function.
Retinoic acid (RA) is converted from retinal by retinaldehyde dehydrogenases (RALDHs) and is an essential signaling molecule in embryonic and adult tissue. We previously reported that RALDH1 was produced in the rat anterior pituitary gland and hypothesized that RA was generated in the gland. Midkine (MK) is an RA-inducible growth factor, and MK production in the rat anterior pituitary gland was recently reported. However, the mechanism that regulates gene expression of MK in the pituitary gland has not been determined. To investigate regulation of MK production in the anterior pituitary gland, we analyzed changes in MK mRNA in cultured rat anterior pituitary cells. We identified MK-expressing cells by double-staining with in situ hybridization and immunohistochemical techniques for RALDH1. MK mRNA was expressed in RALDH1-producing cells in the anterior pituitary gland. Using isolated anterior pituitary cells of rats, we examined the effect of RA on gene expression of MK. Quantitative real-time PCR revealed that 72 h exposure to a concentration of 10-6 M of retinal and all-trans retinoic acid increased MK mRNA levels by about 2-fold. Moreover, the stimulatory effect of all-trans retinoic acid was mimicked by the RA receptor agonist Am80. This is the first report to show that RA is important in regulating MK expression in rat anterior pituitary gland.
There have been reports of the use of levothyroxine or levothyroxine plus liothyronine for consumptive hypothyroidism caused by hepatic hemangiomas. Administration of levothyroxine without liothyronine can be inadequate to maintain normal levels of both free T3 and free T4 in some patients. However, there is no report of treatment with liothyronine plus propranolol. We herein present a case in which we used liothyronine therapy for multifocal hepatic hemangiomas in a Japanese patient with low free T3 and normal free T4 levels. A 2-month-old Japanese male was referred to our hospital because of jaundice. Abdominal computed tomography showed multifocal hemangiomas in both lobes of the liver. TSH level was elevated, free T3 level was low, free T4 level was normal, and hypothyroidism due to hepatic hemangiomas was diagnosed. In addition to propranolol, liothyronine was started. We used liothyronine without levothyroxine for hypothyroidism because only free T3 level had decreased, whereas free T4 level remained in the normal range. The TSH and free T3 levels normalized in this patient in less than 1 month. The liothyronine dose was gradually reduced with regression of the hemangiomas, and liothyronine administration was discontinued at the age of 5 months. At the age of 11 months, growth and neurological development of the patient met age-specific norms, and he was euthyroid at that time. This is the first report demonstrating the use of liothyronine with propranolol for treatment of this type of consumptive hypothyroidism.
We report a 27-year-old pregnant woman with polyuria, polydipsia and headache in the third trimester of pregnancy. Hypernatremia (153 mEq/L), high plasma osmolality (300 mOsm/kgH2O) and low urinary osmolality (92 mOsm/kgH2O) were observed at the admission to our hospital. Plasma arginine vasopressin (AVP) level was inappropriately low (2.2 pg/mL) compared to the high plasma osmolality. Plasma AVP responses to hypertonic-saline infusion were blunted, and her urine osmolality increased in response to desmopressin. The diagnosis of central diabetes insipidus was made from these results. Magnetic resonance imaging (MRI) of hypothalamic-pituitary region demonstrated a significant enlargement of the pituitary stalk, suggesting the presence of hypophysitis. In addition, serum anti-rabphilin-3A antibodies that have been recently reported as a biomarker of lymphocytic infundibulo-neurohypophysitis, were positive. Diabetes insipidus continued after delivery, suggesting that polyuria was not mainly due to excessive vasopressinase activity or reduced renal sensitivity to AVP by prostaglandin E2 that can cause temporal polyuria during pregnancy. We therefore clinically diagnosed central diabetes insipidus due to lymphocytic infundibulo-neurohypophysitis, without performing invasive transsphenoidal pituitary biopsy. This case suggested the usefulness of anti-rabphilin-3A antibodies for the etiological diagnosis of central diabetes insipidus during pregnancy.