Unni Syversen

Long-Term Serotonin Administration Induces Heart Valve Disease in Rats

Background—The purpose of this study was to investigate whether rats dosed with serotonin develop changes similar to those seen in human carcinoid heart disease. Methods and Results—Ten Sprague-Dawley rats were given serotonin injections subcutaneously once daily for 3 months; controls were given saline. A long-lasting hyperserotoninemia with a >10-fold increase in both platelet-poor plasma and dialysate from the femoral muscles appeared. The animals developed clinical signs such as flushing and loose stools. After 3 months, 6 of 10 rats given serotonin had pathological echocardiographs. Two animals had a combination of aortic and pulmonary valve insufficiency, 1 had isolated aortic valve insufficiency, and 3 had isolated pulmonary valve insufficiency. Histopathological examination revealed shortened and thickened aortic cusps and carcinoidlike plaques characterized by a collection of myofibroblasts within an extracellular matrix of collagen ground substance. Immunostaining for Ki-67 demonstrated an increased number of proliferating subendocardial cells. In the control group, no pathological changes were seen. With the use of reverse-transcription polymerase chain reaction, normal rat aortic cusps were shown to express mRNA for serotonin receptors 5-HT1A, 5-HT2A, and 5-HT2B and the serotonin transporter 5-HTT. Conclusions—For the first time, long-term serotonin administration was performed in rats. Morphological and echocardiographic changes similar to those seen in human carcinoid heart disease developed. This study demonstrates that serotonin most likely is involved in the pathogenesis of carcinoid heart disease.

Sustained Nonvertebral Fragility Fracture Risk Reduction After Discontinuation of Teriparatide Treatment

A follow‐up in 1262 women was conducted after the discontinuation of teriparatide. The hazard ratio for combined teriparatide group (20 and 40 μg) for the 50‐month period after baseline was 0.57 (p = 0.002), suggesting a sustained effect in reducing the risk of nonvertebral fragility fracture.

Expression and regulation of resistin in osteoblasts and osteoclasts indicate a role in bone metabolism

The adipose tissue is the site of expression and secretion of a range of biologically active proteins, called adipokines, for example, leptin, adiponectin, and resistin. Leptin has previously been shown to be expressed in osteoblasts and to promote bone mineralization, whereas adiponectin expression is enhanced during osteoblast differentiation. In the present study we explored the possible role of resistin in bone metabolism. We found that resistin is expressed in murine preosteoclasts and preosteoblasts (RAW 264.7, MC3T3‐E1), in primary human bone marrow stem cells and in mature human osteoblasts. The expression of resistin mRNA in RAW 264.7 was increased during differentiation and seemed to be regulated through PKC‐ and PKA‐dependent mechanisms. Recombinant resistin increased the number of differentiated osteoclasts and stimulated NFκB promoter activity, indicating a role in osteoclastogenesis. Resistin also enhanced the proliferation of MC3T3‐E1 cells in a PKA and PKC‐dependent manner, but only weakly interfered with genes known to be upregulated during differentiation of MC3T3‐E1 into osteoblasts. All together, our results indicate that resistin may play a role in bone remodeling. J. Cell. Biochem. 99: 824–834, 2006.

Serotonin and fluoxetine modulate bone cell function in vitro

Recent studies have proposed a role for serotonin and its transporter in regulation of bone cell function. In the present study, we examined the in vitro effects of serotonin and the serotonin transporter inhibitor fluoxetine “Prozac” on osteoblasts and osteoclasts. Human mononuclear cells were differentiated into osteoclasts in the presence of serotonin or fluoxetine. Both compounds affected the total number of differentiated osteoclasts as well as bone resorption in a bell‐shaped manner. RT‐PCR on the human osteoclasts demonstrated several serotonin receptors, the serotonin transporter, and the rate‐limiting enzyme in serotonin synthesis, tryptophan hydroxylase 1 (Tph1). Tph1 expression was also found in murine osteoblasts and osteoclasts, indicating an ability to produce serotonin. In murine pre‐osteoclasts (RAW264.7), serotonin as well as fluoxetine affected proliferation and NFκB activity in a biphasic manner. Proliferation of human mesenchymal stem cells (MSC) and primary osteoblasts (NHO), and 5‐HT2A receptor expression was enhanced by serotonin. Fluoxetine stimulated proliferation of MSC and murine preosteoblasts (MC3T3‐E1) in nM concentrations, µM concentrations were inhibitory. The effect of fluoxetine seemed direct, probably through 5‐HT2 receptors. Serotonin‐induced proliferation of MC3T3‐E1 cells was inhibited by the PKC inhibitor (GF109203) and was also markedly reduced when antagonists of the serotonin receptors 5‐HT2B/C or 5‐HT2A/C were added. Serotonin increased osteoprotegerin (OPG) and decreased receptor activator of NF‐κB ligand (RANKL) secretion from osteoblasts, suggesting a role in osteoblast‐induced inhibition of osteoclast differentiation, whereas fluoxetine had the opposite effect. This study further describes possible mechanisms by which serotonin and the serotonin transporter can affect bone cell function. J. Cell. Biochem. 98: 139–151, 2006.

Glucocorticoid replacement therapy and pharmacogenetics in Addison's disease: effects on bone.

UNLABELLED Context Patients with primary adrenal insufficiency (Addisons disease) receive more glucococorticoids than the normal endogenous production, raising concern about adverse effects on bone. OBJECTIVE To determine i) the effects of glucocorticoid replacement therapy on bone, and ii) the impact of glucocorticoid pharmacogenetics. DESIGN, SETTING AND PARTICIPANTS A cross-sectional study of two large Addisons cohorts from Norway (n=187) and from UK and New Zealand (n=105). MAIN OUTCOME MEASURES Bone mineral density (BMD) was measured; the Z-scores represent comparison with a reference population. Blood samples from 187 Norwegian patients were analysed for bone markers and common polymorphisms in genes that have been associated with glucocorticoid sensitivity. RESULTS Femoral neck BMD Z-scores were significantly reduced in the patients (Norway: mean -0.28 (95% confidence intervals (CI) -0.42, -0.16); UK and New Zealand: -0.21 (95% CI -0.36, -0.06)). Lumbar spine Z-scores were reduced (Norway: -0.17 (-0.36, +0.01); UK and New Zealand: -0.57 (-0.78, -0.37)), and significantly lower in males compared with females (P=0.02). The common P-glycoprotein (ABCB1) polymorphism C3435T was significantly associated with total BMD (CC and CT>TT P=0.015), with a similar trend at the hip and spine. CONCLUSIONS BMD at the femoral neck and lumbar spine is reduced in Addisons disease, indicating undesirable effects of the replacement therapy. The findings lend support to the recommendations that 15-25 mg hydrocortisone daily is more appropriate than the higher conventional doses. A common polymorphism in the efflux transporter P-glycoprotein is associated with reduced bone mass and might confer susceptibility to glucocorticoid induced osteoporosis.

Neuroendocrine differentiation in carcinomas of the prostate. Do neuroendocrine serum markers reflect immunohistochemical findings

The aim of the present study was to examine the correlation between the immunohistochemical findings and the serum markers for neuroendocrine (NE) cells in patients with carcinoma of the prostate. Preoperative serum values of chromogranin A (CgA), chromogranin B (CgB), pancreastatin (Pst), neuron‐specific enolase (NSE), and prostatic specific antigen (PSA) were determined in 22 patients. The tissue specimens were obtained by a palliative transurethral resection of the prostate (TURP) because of urinary outflow obstruction. Immunohistochemistry was performed by using antibodies against CgA, CgB, NSE, serotonin, thyroid‐stimulating hormone (TSH), and somatostatin. Tumor cells with NE differentiation were found in 91% of the cases. No patient had elevated serum values of NSE, despite the presence of NSE‐positive tumor cells in 77% of the tumors. Neither did CgB in serum correlate with the immunohistochemical findings. Elevated serum values of CgA were found in 59% of patients. A positive correlation between the number of CgA‐staining cells and the serum values of CgA was found, as seven out of eight patients with groups of CgA‐positive tumor cells had elevated serum values of CgA. We conclude that CgA, in contrast to NSE, CgB, and Pst, seems to be a useful serum marker in predicting the extent of NE differentiation in prostatic tumors. Prostate 30:1–6, 1997

Neuroendocrine Differentiation in Human Gastric Carcinoma

Distinguishing between neuroendocrine carcinoma and adenocarcinoma may be difficult.

Long-term effects of inhaled nicotine

Tobacco smoking has been reported to be associated with increased risk of cardiovascular disease and cancer, particularly of the lungs. In spite of extensive research on the health effects of tobacco smoking, the substances in tobacco smoke exerting these negative health effects are not completely known. Nicotine is the substance giving the subjective pleasure of smoking as well as inducing addiction. For the first time we report the effect on the rat of long-term (two years) inhalation of nicotine. The rats breathed in a chamber with nicotine at a concentration giving twice the plasma concentration found in heavy smokers. Nicotine was given for 20 h a day, five days a week during a two-year period. We could not find any increase in mortality, in atherosclerosis or frequency of tumors in these rats compared with controls. Particularly, there was no microscopic or macroscopic lung tumors nor any increase in pulmonary neuroendocrine cells. Throughout the study, however, the body weight of the nicotine exposed rats was reduced as compared with controls. In conclusion, our study does not indicate any harmful effect of nicotine when given in its pure form by inhalation.

Treatment of ECL cell carcinoids with octreotide LAR

Background: Patients with chronic atrophic gastritis (CAG) and hypergastrinaemia are at risk of developing hyperplasia of the enterochromaffin‐like (ECL) cells and ECL‐cell‐derived tumours. The effect of the somatostatin analogue octreotide on ECL cell carcinoids is examined. Methods: Five patients with hypergastrinaemia and ECL cell carcinoids were enrolled in a 1‐year study of octreotide LAR (long‐acting release) 20 mg given at monthly intervals. Biopsies from tumours and from flat oxyntic mucosa were done at the start and 3, 6 and 12 months thereafter. Sections were stained with haematoxylin‐erythrosin, immunostained with chromogranin A (CgA) and doublestained with CgA and Ki‐67. Serum gastrin and CgA were measured. Results: The number of visible tumours was reduced by more than 50 %. Sections from both tumours and flat mucosa showed a reduced number of CgA immunoreactive cells. Mean serum gastrin decreased from 421 to 186 pM (normal <40 pM); P > 0.05, and serum CgA from 73 to 25 ng/ml (normal <30 ng/ml); P < 0.001. Conclusions: During treatment the patients were still markedly hypergastrinaemic, whereas the serum CgA showed normalization. A diminished tumour load and reduced ECL cell density were found, indicating an antiproliferative effect of octreotide directly on the ECL cells.

Chromogranin a and Pancreastatin-Like Immunoreactivity in Serum of Gastrinoma Patients

Gastrin and pancreastatin-like immunoreactivity were determined by radioimmunoassay methods and chromogranin A was determined by enzyme-linked immunoassay in sera from 18 patients with gastrinomas (Zollinger-Ellison syndrome) and in 20 age and sex matched controls. Gastrin serum levels in the gastrinoma patients were in the range 26-80,000 pmol/l, and in the controls 5-31 pmol/l. Chromogranin A serum levels in the gastrinoma group were in the range 6-2,700 ng/ml (mean +/- SEM: 400 +/- 147 ng/ml). The mean value of chromogranin A was significantly higher than in the control group (8 +/- 2 ng/ml, p = 0.008). The serum levels of pancreastatin-like immunoreactivity in the gastrinoma patients were in the range 23-1,994 pg/ml (597 +/- 123 pg/ml). The mean value of pancreastatin-like immunoreactivity in the gastrinoma group was significantly higher than in the control group (104 +/- 25 pg/ml, p = 0.0002). The levels of chromogranin A and pancreastatin-like immunoreactivity were significantly higher in patients with verified metastatic disease (p = 0.04, p = 0.01 respectively). There was a significantly positive correlation between levels of gastrin and pancreastatin-like immunoreactivity (r = 0.7, p = 0.002), while no correlation was found between gastrin and chromogranin A levels or between levels of chromogranin A and pancreastatin-like immunoreactivity. The study demonstrates an elevation of both chromogranin A and pancreastatin-like immunoreactivity in serum of gastrinoma patients. The lack of correlation between gastrin and chromogranin A, however, gives an indication that the gastrinoma cells are not the main source of serum chromogranin A elevation.