https://www.grc.com/health/pdf/Sunlight_and_Vitamin_D.pdf

Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease

Context: Altered vitamin D and calcium homeostasis may play a role in the development of type 2 diabetes mellitus (type 2 DM). Evidence Acquisition and Analyses: MEDLINE review was conducted through January 2007 for observational studies and clinical trials in adults with outcomes related to glucose homeostasis. When data were available to combine, meta-analyses were performed, and summary odds ratios (OR) are presented. Evidence Synthesis: Observational studies show a relatively consistent association between low vitamin D status, calcium or dairy intake, and prevalent type 2 DM or metabolic syndrome [OR (95% confidence interval): type 2 DM prevalence, 0.36 (0.16–0.80) among nonblacks for highest vs. lowest 25-hydroxyvitamin D; metabolic syndrome prevalence, 0.71 (0.57–0.89) for highest vs. lowest dairy intake]. There are also inverse associations with incident type 2 DM or metabolic syndrome [OR (95% confidence interval): type 2 DM incidence, 0.82 (0.72–0.93) for highest vs. lowest combined vitamin D an...

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The Role of Vitamin D and Calcium in Type 2 Diabetes. A Systematic Review and Meta-Analysis

• Considerable evidence suggests that the acute effects of antidepressant treatments on brain norepinephrine (NE) and serotonin (5-HT) systems cannot account fully for their delayed therapeutic action. This review evaluates the effects of long-term antidepressant treatment on biogenic amine metabolism and on various indexes of presynaptic and postsynaptic receptor function. In contrast to variable effects on NE and 5-HT turnover and on presynaptic receptor sensitivity, almost all long-term antidepressant treatments produce consistent alterations in a number of measures of postsynaptic amine receptor sensitivity. Longterm treatment has been found to reduce β-adrenergic sensitivity while enhancing responses to serotonergic and α-adrenergic stimulation, suggesting that modulation of receptor sensitivity may be a mechanism of action common to tricyclic antidepressants, "atypical" antidepressants, monoamine oxidase inhibitors, and electroconvulsive therapy. These findings provide support for hypotheses of amine receptor abnormalities in depression and indicate the need for expanded studies of amine receptor function in patients.

Receptor Sensitivity and the Mechanism of Action of Antidepressant Treatment: Implications for the Etiology and Therapy of Depression

The secretion of growth hormone (GH) is regulated through a complex neuroendocrine control system, especially by the functional interplay of two hypothalamic hypophysiotropic hormones, GH-releasing hormone (GHRH) and somatostatin (SS), exerting stimulatory and inhibitory influences, respectively, on the somatotrope. The two hypothalamic neurohormones are subject to modulation by a host of neurotransmitters, especially the noradrenergic and cholinergic ones and other hypothalamic neuropeptides, and are the final mediators of metabolic, endocrine, neural, and immune influences for the secretion of GH. Since the identification of the GHRH peptide, recombinant DNA procedures have been used to characterize the corresponding cDNA and to clone GHRH receptor isoforms in rodent and human pituitaries. Parallel to research into the effects of SS and its analogs on endocrine and exocrine secretions, investigations into their mechanism of action have led to the discovery of five separate SS receptor genes encoding a f...

Neuroendocrine Control of Growth Hormone Secretion

The aim of this study was to determine the association between type-2 diabetes mellitus (DM), BMD and fractures in 6,655 men and women aged 55 years and over from the Rotterdam Study. We compared subjects with type-2 DM to subjects without DM. Additionally, subset analyses were performed, dividing subjects on the basis of the glucose tolerance test into already treated DM, newly diagnosed DM, impaired glucose tolerance (IGT) and normal glucose tolerance (NGT, reference). Femoral neck and lumbar spine BMD were measured using DEXA. Nonvertebral fracture ascertainment was performed using an automated record system involving GPs and local hospitals. Although subjects with DM had higher BMD, they had an increased nonvertebral fracture risk: hazard ratio (HR) 1.33 (1.00-1.77). In subset analysis, the increased fracture risk appeared restricted to treated DM subjects only: HR 1.69 (1.16-2.46). Subjects with IGT had a higher BMD, but contrary to treated DM, they had a lower fracture risk: HR 0.80 (0.63-1.00). In conclusion, subjects with type-2 DM and IGT both have a higher BMD. Whereas, subjects with IGT have a decreased fracture risk, subjects with DM (primarily those with already established and treated DM) had an increased fracture risk, probably due to long-term complications associated with DM.

Bone mineral density and fracture risk in type-2 diabetes mellitus: the Rotterdam Study.

In order to determine whether an adrenergic mechanism is involved in the secretion of growth hormone and insulin, the effect of adrenergic-blocking or -stimulating agents on plasma human growth hormone (HGH), immunoreactive insulin, blood free fatty acids (FFA), and glucose levels was studied in normal human subjects.

The intravenous infusion of propranolol, a beta adrenergic-blocking agent, caused a rise in plasma HGH, a transient decrease in blood FFA, and no significant change in plasma insulin. This increase in plasma HGH was inhibited either by the combined administration of isoproterenol, a beta adrenergic-stimulating agent, along with propranolol or by oral glucose loading immediately before the start of propranolol infusion. The concomitant administration of epinephrine and propranolol brought about a rise in plasma HGH comparable with that produced by propranolol alone, without any significant change in blood FFA. Alpha adrenergic blockade by the intravenous infusion of phenotolamine significantly suppressed plasma HGH responses to insulin-induced hypoglycemia and to arginine infusion, and enhanced plasma insulin response to arginine infusion. It also stimulated lipid mobilization significantly.

The intravenous infusion of alpha adrenergic-stimulating agents, phenylephrine and methoxamine, caused an increase in plasma HGH, a slight decrease in blood FFA, and no significant change in plasma insulin. This increase in plasma HGH was significantly inhibited by the simultaneous administration of phentolamine along with methoxamine. On the contrary, a beta adrenergic stimulant, isoproterenol, raised plasma insulin and blood FFA, and abolished the plasma HGH response to propranolol. Another beta stimulator, isoxsuprine, raised blood FFA but not plasma insulin.

It is concluded that either beta adrenergic blockade or alpha stimulation enhances HGH secretion and inhibits insulin secretion and fat mobilization, whereas either alpha blockade or beta stimulation stimulates insulin secretion and fat mobilization and inhibits HGH secretion.

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Effect of adrenergic-blocking or -stimulating agents on plasma growth hormone, immunoreactive insulin, and blood free fatty acid levels in man

The degree of diabetic osteopenia and serum vitamin D metabolite levels were measured in 168 type 2 (noninsulin-dependent) diabetic patients. Based on six indices obtained by microdensitometry, we found the bone mass in 26.2% of diabetic patients to be clearly decreased and in 11.9% to be severely decreased. Our direct method of analysis of bone mass shows that diabetic osteopenia differs from typical osteoporosis in character. In addition, serum 24,25-dihydroxyvitamin D was significantly decreased (P less than 0.01), but 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D were similar to those of controls.

Diabetic osteopenia and circulating levels of vitamin D metabolites in type 2 (noninsulin-dependent) diabetes

Polymorphism of 5' portion of the human insulin gene was examined in 188 unrelated Japanese subjects (49 normal, 71 with IDDM, and 68 with NIDDM) using restriction endonuclease analysis. Restriction fragments were classified according to the insertion size: Class 1 (600 base pairs), Class 2 (1300 base pairs), and Class 3 (2000 base pairs). We found a very high frequency of Class 1 alleles (96.8%) and a low frequency of both Class 2 (0.8%) and Class 3 alleles (2.4%) and that approximately 94% of the genotypes were Class 1/Class 1 homozygote. In addition, there was no correlation of allelic or genotypic frequency with NIDDM or IDDM. We conclude that length polymorphism of the human insulin gene cannot be a useful marker for diabetes in Japanese.

Mikio Yawata

Papers

Effect of adrenergic-blocking or -stimulating agents on plasma growth hormone, immunoreactive insulin, and blood free fatty acid levels in man

Diabetic osteopenia and circulating levels of vitamin D metabolites in type 2 (noninsulin-dependent) diabetes

The polymorphism linked to the human insulin gene: its lack of association with either IDDM or NIDDM in Japanese.