Sex-dependent right ventricular hypertrophic gene changes after methamphetamine treatment in mice

Abstract

Methamphetamine (MA) abuse is associated with the development of pulmonary arterial hypertension (PAH) and subsequent right ventricular failure. A recent clinical study demonstrated that female sex is a major risk factor for MA-induced PAH. The mechanisms associated with increased prevalence and severity of MA-induced PAH in females are still unclear. We hypothesized that MA may promote changes in gene expression in the right ventricle contributing to the development and/or worsening of PAH in females. Male and female C57BL/6 mice were treated with either MA or vehicle. Right and left ventricular systolic pressures (RVSP and LVSP, respectively) were assessed and tissue samples were collected for gene expression and histology. LVSP and RVSP were not affected by MA in either males or females. Right ventricular hypertrophy was significantly increased by MA in females but it was not affected by MA in males. In the female mice, MA-induced right ventricular hypertrophy was associated with increased expression of brain natriuretic peptide gene and members of the TGF-β receptor signaling pathway such as TGF-β receptor-1, smad3 and smad7. In male mice, there were no changes in right ventricular gene expression. Our results suggest that MA caused right ventricular hypertrophy in female mice, but not in males and that this was associated with an increase in hypertrophic genes. The right ventricular hypertrophy was not dependent on increased RVSP suggesting a direct effect of MA on the right ventricle. If this translates to PAH patients, it might explain the poor outcome observed in MA-associated female PAH patients.

Keywords: Methamphetamine; Right ventricular hypertrophy; Sexual dimorphism; pulmonary arterial hypertension.

Fig. 1

Methamphetamine (MA) or vehicle treatment in female mice had no effect on right ventricular systolic pressure (A) Heart rate (B) or right heart contractility (C and D). Results are expressed as mean ± standard error of the mean (S.E.M) (n = 5–6).

Fig. 2

Methamphetamine or vehicle treatment in male mice had no effect on right ventricular systolic pressure (A) Heart rate (B) or right heart contractility (C and D). Results are expressed as mean ± standard error of the mean (S.E.M) (n = 8 each).

Fig. 3

Methamphetamine or vehicle treatment in female mice did not affect left ventricular systolic pressure (A) Heart rate (B) or left heart contractility (C and D). Results are expressed as mean ± standard error of the mean (S.E.M) (n = 4–6).

Fig. 4

Methamphetamine or vehicle treatment in male mice did not affect left ventricular systolic pressure (A) Heart rate (B) or left heart contractility (C and D). Results are expressed as mean ± standard error of the mean (S.E.M) (n = 4–5).

Fig. 5

Expression of genes associated with PAH and fibrosis in lung tissue isolated from A) vehicle- (white) and methamphetamine- (black) treated female mice and B) vehicle- (white) and methamphetamine- (black) treated male mice. BMPR2 (Bone Morphogenetic Protein Receptor Type II), HTR1B (5-Hydroxytryptamine (Serotonin) Receptor 1B), TGFβR1 (Transforming Growth Factor Beta Receptor I), ESR 1 (Estrogen Receptor Alpha), ESR 2 (Estrogen Receptor Beta), GPER (G Protein-Coupled Estrogen Receptor 1), TGFβ1 (Transforming Growth Factor Beta 1), CYP1A1 (Cytochrome P450 Family 1 Subfamily A polypeptide 1),CYP1B1 (Cytochrome P450 Family 1 Subfamily B, Polypeptide 1), Col1a1 (collagen type I), Col3a1 (collagen type III), FN1 (fibronectin 1). Results are expressed as mean ± standard error of the mean (S.E.M) (n = 6). *P < 0.05 vs. vehicle group.

Fig. 6

Expression of genes associated with PAH and fibrosis in the RV tissue isolated from A) vehicle- (white) and methamphetamine- (black) treated female mice and B) vehicle- (white) and methamphetamine- (black) treated male mice. ANP (natriuretic peptide type A), BNP (natriuretic peptide type B), BMPR2 (Bone Morphogenetic Protein Receptor Type II), HTR1B (5-Hydroxytryptamine (Serotonin) Receptor 1B), TGFβR1 (Transforming Growth Factor Beta Receptor I), TGFβ1 (Transforming Growth Factor Beta 1), Col1a1 (collagen type I), Col3a1 (collagen type III), FN1 (fibronectin 1), Smad 2 (SMAD family member 2), Smad 3 (SMAD family member 3), Smad 7 (SMAD family member 7), Smurf 1 (SMAD specific E3 ubiquitin protein ligase 1), Smurf 2 (SMAD specific E3 ubiquitin protein ligase 2). Results are expressed as mean ± standard error of the mean (S.E.M) (n = 6). *P < 0.05 vs. vehicle group.

Fig. 7

Pulmonary vascular immunostaining for A) the proliferation marker; proliferating cell nuclear antigen (PCNA) (n = 5–6), and for B) α-smooth muscle actin (α-SMA) (n = 6 each group). Results are expressed as mean ± standard error of the mean (S.E.M). Scale bars indicate 20 μm.