Deoxycorticosterone Acetate-Salt Mice Exhibit Blood Pressure–Independent Sexual Dimorphism

Abstract

Abstract-We tested the hypothesis that female and male mice differ in terms of cardiac hypertrophy after deoxycorticosterone acetate (DOCA)ϩsalt hypertension (uninephrectomy and 1% saline in drinking water) and focused on calcineurin signaling. We excluded confounding effects of blood pressure elevation or sex-related blood pressure differences by treating DOCA-salt mice with hydralazine (250 mg/L in drinking water). We found that directly measured mean arterial blood pressure was lowered to control values with hydralazine and corroborated this finding in separate mouse groups with radiotelemetry. Male mice were more responsive to DOCA-salt-related effects. They developed more left ventricular hypertrophy and more renal hypertrophy after 6 weeks of DOCA-saltϩhydralazine compared with female mice. In hearts, transcripts for calcineurin A␤ and for myocyte-enriched calcineurin interacting protein 1 were upregulated in male but not in female mice. Enhanced activity of calcineurin A␤, as indicated by diminished phosphorylation of NFATc2 in male mice, accounted for this sex-specific difference. Stretch-related, inflammatory, and profibrotic responses were also accentuated in male mice, as shown by higher transcript levels of atrial natriuretic peptide, monocyte chemoattractant protein-1, and transforming growth factor-␤. Our results support sex-specific regulation of the calcineurin pathway in response to largely blood pressure-independent mineralocorticoid action. We suggest that sex-specific calcineurin activation determines the maladaptive cardiac and renal hypertrophic responses and accompanying organ injury in male mice. Key Words: heart Ⅲ kidney Ⅲ hypertrophy Ⅲ inflammation Ⅲ fibrosis Ⅲ calcineurin Ⅲ MCIP1 Ⅲ NFATc2 S ex differences in cardiac 1 and renal 2 function are well established. Women have a lower overall incidence of left ventricular (LV) hypertrophy 3 and nondiabetic renal disease than men. 4 Less pronounced injury in female animals has been attributed to estradiol-mediated protective effects. 5 Male vulnerability was related to detrimental effects of androgens. 6 Gonadal steroids regulate renal and systemic hemodynamics, as well as renal sodium handling. 7 Chronic salt overload is a major cardiovascular stressor that sets in motion a series of adaptive processes in hearts and kidneys in patients with renal dysfunction. 8,9 Deoxycorticosterone acetate (DOCA)ϩsalt acts similarly to aldosterone, promotes sodium retention and potassium excretion in the distal nephron, and serves as a "prototype" model for salt-sensitive low-renin hypertension. 10 Rats or mice with DOCA-salt hypertension develop sex-specific differences in cardiorenal target-organ damage that are mainly attributed to more delayed and less extensive blood pressure increases in females compared with males. 11 Whether sex-specific differences in cardiorenal damage still exist in the context of independent systemic blood pressure responses to salt overload has not been studied. We hypothesized that female mice have endogenous compensatory mech...

Estrogen Receptor-β Signals Left Ventricular Hypertrophy Sex Differences in Normotensive Deoxycorticosterone Acetate-Salt Mice

“…27 The involvement of the activated calcineurin pathway in a blood pressure-independent manner was shown previously to be restricted to male DOCA-salt mice. 8 We found only a weak increase in calcineurin with concomitant upregulation of calcineurin regulating protein MCIP1.4 in hearts of ER␤-deficient DOCA females. The fibrotic response and collagen I and III distributions were particularly prominent in the hearts of ER␤-deficient DOCA-salt females.…”

“…8 Male WT mice tended to greater heart weight:tibia length ratios than female WT mice ( Figure 2A). ER␤ Ϫ/Ϫ females developed the highest heart weight:tibia length ratios, exceeding those observed in WT males ( Figure 2A).…”

“…8 Very high expression levels of the regulated calcineurin subunit A␤ were observed in DOCA male but not female WT mice WTs. We next assessed transcription of a calcineurin target gene, the 1.4 isoform of myocyte-enriched calcineurininteracting protein (MCIP1.4), which reflects calcineurin activity.…”

“…8 Real-time PCR was performed in the Applied Biosystems 7500 Fast Real-Time PCR system (Applied Biosystems). The relative amount of gene transcript was calculated by the cycle threshold method using the Applied Biosystems 7500 System version 1.2.3 software and normalized for the endogenous reference (␤2 microglobulin).…”

“…7 We described recently a sex-specific dimorphism in cardiac adaptation in response to deoxycorticosterone acetate (DOCA)-salt and showed that this response was independent of blood pressure. 8 Male mice developed left ventricular hypertrophy (LVH) that was linked to activation of a calcineurin-dependent pathway, which increased proinflammatory and profibrotic responses. In contrast, female DOCA mice maintained their initial physiological adaptive cardiac phenotype despite mineralocorticoid and salt challenge.…”