Altered activities of CYP1A1 and CYP19A1 enzymes in women using SSRI medication during pregnancy

INTRODUCTION

Selective serotonin reuptake inhibitors (SSRIs) are commonly used medication for the treatment of depression during pregnancy. Their use may affect various biological molecules such as enzymes which regulate placental hormonal production and xenobiotic metabolism. Our aim was to investigate the effect of maternal SSRI use on activities of three placental enzymes.

METHODS

We analyzed activities of xenobiotic metabolism enzymes cytochrome P450 1A1 (CYP1A1), aromatase (CYP19A1), and glutathione-S-transferase (GST) from placental microsomal and cytosolic subcellular fractions. Term placentas were collected from 47 SSRI users and 49 control women participating Kuopio Birth cohort (KuBiCo) during the years 2013-2015. Among SSRI users, escitalopram was the most widely used SSRI medication.

RESULTS

The mean enzyme activities of all studied enzymes were lower in SSRI users compared to controls. A statistically significant difference was observed in the enzyme activities of CYP19A1 (p = 0.001) and CYP1A1 (p = 0.002) between the study groups after adjusting for use of additional medication, gestational diabetes, sex of the newborn and gestational weeks at delivery. SSRI use had no significant effect on placental GST enzyme activity.

DISCUSSION

Our results indicate that SSRI medication alters placental enzyme activities. This may lead disturbances in maternal steroid hormone balance as well as in xenobiotic metabolism and may provide risk for both developing fetus and pregnant women.

Long-term thiazide use and risk of low-energy fractures among persons with Alzheimer's disease-nested case-control study

We investigated the association between thiazide use and the risk of low-energy fractures among community dwellers with Alzheimer's disease. Longer use was associated with a decreased risk of low-energy fractures. This study extends the previous knowledge of reduced fracture risk of thiazides to persons with Alzheimer's disease.

INTRODUCTION

To investigate the association between thiazide use and the risk of low-energy fractures (LEF), and hip fracture among community dwellers with Alzheimer's disease (AD). No prior study has evaluated the effect of thiazides on LEF risk of AD patients.

METHODS

LEF cases were identified from the MEDALZ study, including all community-dwelling persons diagnosed with AD in Finland 2005-2011. During the follow-up from AD diagnoses until the end of 2015, cases with LEF (N = 10,416) and hip fracture (N = 5578) were identified. LEF cases were matched with up to three controls without LEF, according to time since AD diagnosis, age and gender. Thiazide use identified from the Prescription register data was modeled with PRE2DUP method. Current use was defined in 0-30 days' time window before the fracture/matching date, and duration of current use was assessed. The association between thiazide exposure and LEFs was assessed with conditional logistic regression.

RESULTS

Current thiazide use was observed in 10.5% of LEF cases and 12.5% of controls. Current thiazide use was associated with a decreased risk of LEF (adjusted OR [aOR] 0.83, 95% CI 0.77-0.88). In terms of the duration of use, no association was observed with short-term use (< 1 year or 1-3 years), while longer use (> 3 years) was associated with a reduced risk of LEF (aOR 0.77, 95% CI 0.71-0.83) and hip fracture (aOR 0.68, 95% CI 0.60-0.78).

CONCLUSIONS

Our study extends the previous knowledge of reduced fracture risk of thiazides to persons with AD, a population with significantly increased background risk of fractures.

Plasma levels of the proprotein convertase furin and incidence of diabetes and mortality

BACKGROUND

Diabetes mellitus is linked to premature mortality of virtually all causes. Furin is a proprotein convertase broadly involved in the maintenance of cellular homeostasis; however, little is known about its role in the development of diabetes mellitus and risk of premature mortality.

OBJECTIVES

To test if fasting plasma concentration of furin is associated with the development of diabetes mellitus and mortality.

METHODS

Overnight fasted plasma furin levels were measured at baseline examination in 4678 individuals from the population-based prospective Malmö Diet and Cancer Study. We studied the relation of plasma furin levels with metabolic and hemodynamic traits. We used multivariable Cox proportional hazards models to investigate the association between baseline plasma furin levels and incidence of diabetes mellitus and mortality during 21.3-21.7 years follow-up.

RESULTS

An association was observed between quartiles of furin concentration at baseline and body mass index, blood pressure and plasma concentration of glucose, insulin, LDL and HDL cholesterol (|0.11| ≤ β ≤ |0.31|, P < 0.001). Plasma furin (hazard ratio [HR] per one standard deviation increment of furin) was predictive of future diabetes mellitus (727 events; HR = 1.24, CI = 1.14-1.36, P < 0.001) after adjustment for age, sex, body mass index, systolic and diastolic blood pressure, use of antihypertensive treatment, alcohol intake and fasting plasma level of glucose, insulin and lipoproteins cholesterol. Furin was also independently related to the risk of all-cause mortality (1229 events; HR = 1.12, CI = 1.05-1.19, P = 0.001) after full multivariable adjustment.

CONCLUSION

Individuals with high plasma furin concentration have a pronounced dysmetabolic phenotype and elevated risk of diabetes mellitus and premature mortality.

Endothelin-1 signalling controls early embryonic heart rate in vitro and in vivo

AIM

Spontaneous activity of embryonic cardiomyocytes originates from sarcoplasmic reticulum (SR) Ca(2+) release during early cardiogenesis. However, the regulation of heart rate during embryonic development is still not clear. The aim of this study was to determine how endothelin-1 (ET-1) affects the heart rate of embryonic mice, as well as the pathway through which it exerts its effects.

METHODS

The effects of ET-1 and ET-1 receptor inhibition on cardiac contraction were studied using confocal Ca(2+) imaging of isolated mouse embryonic ventricular cardiomyocytes and ultrasonographic examination of embryonic cardiac contractions in utero. In addition, the amount of ET-1 peptide and ET receptor a (ETa) and b (ETb) mRNA levels were measured during different stages of development of the cardiac muscle.

RESULTS

High ET-1 concentration and expression of both ETa and ETb receptors was observed in early cardiac tissue. ET-1 was found to increase the frequency of spontaneous Ca(2+) oscillations in E10.5 embryonic cardiomyocytes in vitro. Non-specific inhibition of ET receptors with tezosentan caused arrhythmia and bradycardia in isolated embryonic cardiomyocytes and in whole embryonic hearts both in vitro (E10.5) and in utero (E12.5). ET-1-mediated stimulation of early heart rate was found to occur via ETb receptors and subsequent inositol trisphosphate receptor activation and increased SR Ca(2+) leak.

CONCLUSION

Endothelin-1 is required to maintain a sufficient heart rate, as well as to prevent arrhythmia during early development of the mouse heart. This is achieved through ETb receptor, which stimulates Ca(2+) leak through IP3 receptors.

Pregnane X receptor agonists impair postprandial glucose tolerance

We conducted a randomized, open, placebo-controlled crossover trial to investigate the effects of the pregnane X receptor (PXR) agonist rifampin on an oral glucose tolerance test (OGTT) in 12 healthy volunteers. The subjects were administered 600 mg rifampin or placebo once daily for 7 days, and OGTT was performed on the eighth day. The mean incremental glucose and insulin areas under the plasma concentration-time curves (AUC(incr)) increased by 192% (P = 0.008) and 45% (P = 0.031), respectively. The fasting glucose, insulin, and C-peptide, and the homeostasis model assessment for insulin resistance, were not affected. The glucose AUC(incr) during OGTT was significantly increased in rats after 4-day treatment with pregnenolone 16α-carbonitrile (PCN), an agonist of the rat PXR. The hepatic level of glucose transporter 2 (Glut2) mRNA was downregulated by PCN. In conclusion, both human and rat PXR agonists elicited postprandial hyperglycemia, suggesting a detrimental role of PXR activation on glucose tolerance.

Regulation of cardiac melusin gene expression by hypertrophic stimuli in the rat

AIM

Melusin is an integrin β1-interacting protein proposed to act as a biomechanical sensor in the heart. We characterized mechanisms and signalling pathways regulating cardiac melusin expression.

METHODS

Infusion of arginine(8) -vasopressin (AVP) in Sprague-Dawley (SD) rats, spontaneously hypertensive rats (SHR) and double transgenic rats (dTGR) harbouring both human angiotensinogen and renin genes as well as infusion of angiotensin II (Ang II) in SD rats were used. The effect of direct left ventricular (LV) wall stretch was analysed by using isolated perfused rat heart preparation. For the cell culture studies, mouse atrial HL-1 cell line and neonatal rat ventricular myocytes (NRVMs) were used.

RESULTS

Left atrial melusin mRNA levels increased already after 30 min of AVP infusion. Ang II caused significant upregulation of left atrial melusin mRNA (2.1-fold at 6 h, P < 0.05) and protein (1.9-fold at 72 h, P < 0.05) levels. In contrast, LV melusin mRNA levels remained unchanged in response to both infusions, as well as to aortic banding-induced pressure overload. Direct LV wall stress or late-stage hypertensive heart disease did not modify LV melusin gene expression either. Interestingly, in atrial HL-1 cells, cyclic stretching increased melusin mRNA levels. Stretching and treatments with hypertrophic agonists increased melusin mRNA and protein levels in NRVMs, endothelin-1 being the most potent. PD98059, an extracellular signal-regulated protein kinase 1/2 inhibitor, markedly attenuated the endothelin-1-induced upregulation of melusin gene expression in NRVMs.

CONCLUSION

Multiple hypertrophic stimuli regulate melusin expression predominately in the atria, which may represent a necessary initial step in early adaptive remodelling processes.

Tumour necrosis factor-like weak inducer of apoptosis (TWEAK) and its receptor Fn14 during cardiac remodelling in rats

AIM

Accumulating evidence supports the concept that proinflammatory cytokines play an essential role in the failing heart. We examined the concomitant tumour necrosis factor-like weak inducer of apoptosis (TWEAK)/Fn14 expression in myocytes in vitro as well as in vivo in cardiac remodelling.

METHODS

We assessed TWEAK and its receptor Fn14 expression in response to angiotensin (Ang) II, myocardial infarction (MI) as well as to local adenovirus-mediated p38 gene transfer in vivo. The effect of various hypertrophic factors and mechanical stretch was studied in neonatal rat ventricular myocyte cell culture.

RESULTS

Ang II increased Fn14 levels from 6 h to 2 weeks, the greatest increase in mRNA levels being observed at 6 h (6.3-fold, P < 0.001) and protein levels at 12 h (4.9-fold, P < 0.01). TWEAK mRNA and protein levels remained almost unchanged during Ang II infusion. Likewise, a rapid and sustained elevation of Fn14 mRNA and protein levels in the left ventricle was observed after experimental MI. Moreover, local p38 gene transfer increased Fn14 mRNA and protein but not TWEAK levels. Fn14 immunoreactive cells were mainly proliferating non-myocytes in the inflammation area while TWEAK immunoreactivity localized to cardiomyocytes and endothelial cells of the coronary arteries. Hypertrophic agonists and lipopolysaccharide increased Fn14 but not TWEAK gene expression in neonatal rat myocytes, while mechanical stretch upregulated Fn14 and downregulated TWEAK gene expression.

CONCLUSIONS

In conclusion, the cardiac TWEAK/Fn14 pathway is modified in response to myocardial injury, inflammation and pressure overload. Furthermore, our findings underscore the importance of Fn14 as a mediator of TWEAK/Fn14 signalling in the heart and a potential target for therapeutic interventions.

The effect of a short-term hypocaloric diet on liver gene expression and metabolic risk factors in obese women

BACKGROUND AND AIMS

Most gene expression studies examining the effect of obesity and weight loss have been performed using adipose tissue. However, the liver also plays a central role in maintaining energy balance. We wanted to study the effects of a hypocaloric diet on overall hepatic gene expression and metabolic risk factors.

METHODS AND RESULTS

The study subjects were middle-aged, obese women. The diet intervention subjects (n=12) were on a hypocaloric, low-fat diet for 8 weeks with a daily energy intake of 5.0 MJ (1200 kcal), while the control subjects (n=19) maintained their weight. Liver biopsies were taken at the end of the diet period during a gallbladder operation. Hepatic gene expression was analyzed using microarrays by comparing the gene expression profiles from four subjects per group. A global decrease in gene expression was observed with 142 down-regulated genes and only one up-regulated gene in the diet intervention group. The diet resulted in a mean weight loss of 5% of body weight. Triglyceride and fasting insulin concentrations decreased significantly after the diet.

CONCLUSIONS

The global decrease in hepatic gene expression was unexpected but the results are interesting, since they included several genes not previously linked to weight reduction. However, since the comparison was made only after the weight reduction, other factors in addition to weight loss may also have been involved in the differences in gene expression between the groups. The decrease in triglyceride and fasting plasma insulin concentrations is in accordance with results from previous weight-loss studies.