Mice carrying a targeted disruption of the Npr1 gene (coding for guanylyl cyclase/natriuretic peptide receptor A (NPRA)) exhibit increased blood pressure, cardiac hypertrophy, and congestive heart failure, similar to untreated human hypertensive patients. The objective of this study was to determine whether permanent ablation of NPRA signaling in mice alters the expression of matrix metalloproteinase (MMP)-2 and MMP-9 and proinflammatory mediators such as tumor necrosis factor-␣ (TNF-␣), leading to myocardial collagen remodeling. Here, we report that expression levels of the MMP-2 and MMP-9 genes were increased by 3-5-fold and that the expression of the TNF-␣ gene was enhanced by 8-fold in Npr1 homozygous null mutant (Npr1 ؊/؊ ) mouse hearts compared with wild-type (Npr1 ؉/؉ ) control mouse hearts. Myocardial fibrosis, total collagen, and the collagen type I/III ratio (p < 0.01) were dramatically increased in adult Npr1 ؊/؊ mice compared with agematched wild-type counterparts. Hypertrophic marker genes, including the ␤-myosin heavy chain and transforming growth factor-␤1, were significantly up-regulated (3-5-fold) in both young and adult Npr1 ؊/؊ mouse hearts. NF-B binding activity in ventricular tissues was enhanced by 4-fold with increased translocation of the p65 subunit from the cytoplasmic to nuclear fraction in Npr1 ؊/؊ mice. Our results show that reduced NPRA signaling activates MMP, transforming growth factor-␤1, and TNF-␣ expression in Npr1 ؊/؊ mouse hearts. The findings of this study demonstrate that disruption of NPRA/cGMP signaling promotes hypertrophic growth and extracellular matrix remodeling, leading to the development of cardiac hypertrophy, myocardial fibrosis, and congestive heart failure. Atrial (ANP)1 and brain (BNP) natriuretic peptides elicit natriuretic, diuretic, vasorelaxant, and anti-proliferative responses, all of which contribute to the regulation of blood pressure and blood volume homeostasis (1, 2). ANP and BNP bind to guanylyl cyclase/natriuretic peptide receptor A (NPRA), which is considered a major natriuretic peptide receptor that synthesizes the intracellular second messenger cGMP (3). Mice carrying a targeted disruption of the Npr1 gene (encoding NPRA) exhibit hypertension, marked cardiac hypertrophy, and congestive heart failure, with sudden death after 6 months of age (4 -6). On the other hand, Npr1 gene-duplicated mice have stimulated levels of guanylyl cyclase activity and increased accumulation of intracellular cGMP in a gene dose-dependent manner and exhibit protection against high salt diets (7). In vitro studies have shown that the ANP/NPRA system exerts growth inhibitory effects on hypertrophic agonist-induced proliferation of cardiac myocytes (8, 9), fibroblasts (10), and mesangial and human vascular smooth muscle cells (11,12). Furthermore, transgenic mice overexpressing ANP have smaller hearts compared with wild-type mice, and ANP gene delivery attenuates cardiac hypertrophy in spontaneously hypertensive rats (13). Nonetheless, the molecular mechanism by which the...

We have identified a GDAY motif in the C-terminal domain of guanylyl cyclase (guanylate cyclase)/NPRA (natriuretic peptide receptor A) sequence, which serves a dual role as an internalization signal and a recycling signal. To delineate the role of the GDAY motif in receptor internalization and sequestration, we mutated Gly920, Asp921 and Tyr923 to alanine residues (GDAY/AAAA) in the NPRA cDNA sequence. The cDNAs encoding wild-type and mutant receptors were transfected in HEK-293 cells (human embryonic kidney 293 cells). The internalization studies of ligand-receptor complexes revealed that endocytosis of 125I-ANP by HEK-293 cells expressing G920A, Y923A or GDAY/AAAA mutant receptor was decreased by almost 50% (P<0.001) when compared with cells expressing the wild-type receptor. However, the effect of D921A mutation on receptor internalization was minimal. Ligand-mediated down-regulation of G920A, Y923A and GDAY/AAAA mutant receptors was decreased by 35-40% when compared with wild-type NPRA. Subsequently, the recycling of internalized D921A and GDAY/AAAA mutant receptors from the intracellular pool was decreased by more than 40+/-4% when compared with wild-type NPRA. Recycling of G920A and Y923A mutant receptors was also decreased, but to a significantly lesser extent compared with the D921A or GDAY/AAAA mutant receptors. We conclude that the Gly920 and Tyr923 residues within the GDAY consensus motif are necessary for internalization, and that residue Asp921 is important for recycling of NPRA. The current results provide new evidence for a dual role of the GDAY sequence motif in ligand-mediated internalization, recycling and down-regulation of a single-transmembrane receptor protein NPRA.

We compared the efficacy of spironolactone (50 mg/d) with metformin (1000 mg/d) after random allocation in 82 adolescent and young women with polycystic ovary syndrome (PCOS) on body mass index (BMI), waist-to-hip ratio, blood pressure, menstrual cyclicity, hirsutism, hormonal levels, glycemia, and insulin sensitivity at baseline and at the 3rd and 6th months of treatment. Sixty-nine women who completed the follow-up had a mean age of 22.6 +/- 5.0 yr and mean BMI of 26.8 +/- 4.0 kg/m2. The number of menstrual cycles in the spironolactone and metformin groups increased from 6.6 +/- 2.1 and 5.7 +/- 2.3 at baseline to 9.0 +/- 1.9 and 7.4 +/- 2.6 at 3rd month and to 10.2 +/- 1.9 and 9.1 +/- 2.0/ year at the 6th month (P = 0.0037), respectively. The hirsutism score decreased from 12.9 +/- 3.2 and 12.5 +/- 4.9 at baseline to 10.1 +/- 3.1 and 11.4 +/- 4.1 at the 3rd month and to 8.7 +/- 1.9 and 10.0 +/- 3.3 at the 6th month, respectively. Both groups showed improvement in glucose tolerance and insulin sensitivity, although the metformin effect was significant in the latter. Serum LH/FSH and testosterone decreased in both groups. BMI, waist-to-hip ratio, and blood pressure did not change with either drug. We conclude that both drugs are effective in the management of PCOS. Spironolactone appears better than metformin in the treatment of hirsutism, menstrual cycle frequency, and hormonal derangements and is associated with fewer adverse events.

The combination of low-dose spironolactone with metformin seems superior to either drug alone in terms of clinical benefits and compliance in women with PCOS.

We conducted a pilot study in 10 adult male schizophrenics, 5 with predominantly positive symptoms (group I) and 5 with predominantly negative symptoms (group II), and 10 healthy matched controls. No significant differences in serum levels of testosterone (T), dehydroepiandrosterone sulfate (DHEAS), estradiol, and cortisol were found between patients as a whole and controls, using radioimmunoassay. However, serum T and DHEAS levels were lower (P <0.05) in group II patients than in group I. Body hair and aggression scores also were lower (P <0.05) in group II. In a much larger sample, Shirayama and colleagues also showed that "moderate negative symptoms, but not low negative symptoms" correlated negatively with T (P <0.05), but positively with ACTH (P <0.05) and cortisol (P <0.01) levels in plasma. Neuroactive steroids, such as DHEAS, and other sex hormones, including their synthetic derivatives, may have an adjunctive role in reversing or slowing the progression of negative symptoms. Indeed, "DHEA augmentation" improved "negative (P <0.01), depressive (P <0.05), and anxiety (P <0.01) symptoms."