Lack of sexual dimorphism in a mouse model of isoproterenol-induced cardiac dysfunction.

Sex-related differences in cardiovascular diseases are highly complex in humans and model-dependent in experimental laboratory animals. The objective of this work was to comprehensively investigate key sex differences in the response to acute and prolonged adrenergic stimulation in C57Bl/6NCrl mice. Cardiac function was assessed by trans-thoracic echocardiography before and after acute adrenergic stimulation (a single sub-cutaneous dose of isoproterenol 10 mg/kg) in 15 weeks old male and female C57Bl/6NCrl mice. Thereafter, prolonged adrenergic stimulation was achieved by sub-cutaneous injections of isoproterenol 10 mg/kg/day for 14 days in male and female mice. Cardiac function and morphometry were assessed by trans-thoracic echocardiography on the 15th day. Thereafter, the mice were euthanized, and the hearts were collected. Histopathological analysis of myocardial tissue was performed after staining with hematoxylin & eosin, Masson's trichrome and MAC-2 antibody. Gene expression of remodeling and fibrotic markers was assessed by real-time PCR. Cardiac function and morphometry were also measured before and after isoproterenol 10 mg/kg/day for 14 days in groups of gonadectomized male and female mice and sham-operated controls. In the current work, there were no statistically significant differences in the positive inotropic and chronotropic effects of isoproterenol between male and female C57Bl/6NCrl. After prolonged adrenergic stimulation, there was similar degree of cardiac dysfunction, cardiac hypertrophy, and myocardial fibrosis in male and female mice. Similarly, prolonged isoproterenol administration induced hypertrophic and fibrotic genes in hearts of male and female mice to the same extent. Intriguingly, gonadectomy of male and female mice did not have a significant impact on isoproterenol-induced cardiac dysfunction as compared to sham-operated animals. The current work demonstrated lack of significant sex-related differences in isoproterenol-induced cardiac hypertrophy, dysfunction, and fibrosis in C57Bl/6NCrl mice. This study suggests that female sex may not be sufficient to protect the heart in this model of isoproterenol-induced cardiac dysfunction and underscores the notion that sexual dimorphism in cardiovascular diseases is highly model-dependent.

Sexual Dimorphism in Doxorubicin-induced Systemic Inflammation: Implications for Hepatic Cytochrome P450 Regulation.

Doxorubicin (DOX) is an effective chemotherapeutic agent used to treat a wide variety of malignancies. In addition to its multi-organ toxicity, DOX treatment has been shown to induce systemic inflammation in patients and experimental animals. Inflammation alters the expression of hepatic cytochrome P450 (CYP) enzymes, which play important roles in drug metabolism and DOX-induced toxicity. Significant sex differences have been reported in DOX-induced toxicity; however, sex differences in DOX-induced systemic inflammation and the potential effects on hepatic CYP expression have not been determined. In the current work, male and female C57Bl/6 mice were administered DOX (20 mg/kg by intraperitoneal injection), and groups of mice were sacrificed 24 and 72 h after DOX administration. DOX elicited a systemic inflammatory response in both male and female mice, but the inflammatory response was stronger in male mice. DOX altered the expression of hepatic CYP isoforms in a sex-dependent manner. Most notably, inhibition of Cyp2c29 and Cyp2e1 was stronger in male than in female mice, which paralleled the sex differences in systemic inflammation. Therefore, sex differences in DOX-induced systemic inflammation may lead to sexually dimorphic drug interactions, in addition to contributing to the previously reported sexual dimorphism in specific DOX-induced organ toxicity.

In vitro and in vivo pharmacological characterization of 5-[(R)-2-(5,6-diethyl-indan-2-ylamino)-1-hydroxy-ethyl]-8-hydroxy-1H-quinolin-2-one (indacaterol), a novel inhaled beta(2) adrenoceptor agonist with a 24-h duration of action.

Here, we describe the preclinical pharmacological profile of 5-[(R)-2-(5,6-diethyl-indan-2-ylamino)-1-hydroxy-ethyl]-8-hydroxy-1H-quinolin-2-one (indacaterol), a novel, chirally pure inhaled beta(2) adrenoceptor agonist, in comparison with marketed drugs. Indacaterol is close to a full agonist at the human beta(2) adrenoceptor (E(max) = 73 +/- 1% of the maximal effect of isoprenaline; pEC(50) = 8.06 +/- 0.02), whereas salmeterol displays only partial efficacy (38 +/- 1%). The functional selectivity profile of indacaterol over beta(1) human adrenoceptors is similar to that of formoterol, whereas its beta(3) adrenoceptor selectivity profile is similar to that of formoterol and salbutamol. In isolated superfused guinea pig trachea, indacaterol has a fast onset of action (30 +/- 4 min) similar to formoterol and salbutamol, and a long duration of action (529 +/- 99 min) comparable with salmeterol. In the conscious guinea pig, when given intratracheally as a dry powder, indacaterol inhibits 5-hydroxytryptamine-induced bronchoconstriction for at least 24 h, whereas salmeterol, formoterol, and salbutamol have durations of action of 12, 4, and 2 h, respectively. When given via nebulization to anesthetized rhesus monkeys, all of the compounds dose-dependently inhibit methacholine-induced bronchoconstriction, although indacaterol produces the most prolonged bronchoprotective effect and induces the lowest increase in heart rate for a similar degree of antibronchoconstrictor activity. In conclusion, the preclinical profile of indacaterol suggests that this compound has a superior duration of action compatible with once-daily dosing in human, together with a fast onset of action and an improved cardiovascular safety profile over marketed inhaled beta(2) adrenoceptor agonists.

Dual and selective antagonism of neurokinin NK(1) and NK(2) receptor-mediated responses in human colon mucosa.

The neurokinin (NK) receptors, NK(1) and NK(2), which are activated by substance P (SP) and NKA, have been identified as potential therapeutic targets in irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). Here we have investigated the effects of a novel dual NK(1) and NK(2) receptor antagonist, namely DNK333 upon responses elicited by [Sar(9), Met(O(2))(11)]-SP (SMSP) and [betaAla(8)]-NKA(4-10) in isolated human colon mucosa mounted in Ussing chambers. A selective NK(1) receptor antagonist, SR140333 and NK(2) receptor antagonist, SR48968 have been tested for comparison. Additions of SMSP (100 nM) or [betaAla(8)]-NKA(4-10) (100 nM) increased basal short-circuit current and responses to both peptides were inhibited by DNK333, while SR140333 only inhibited SMSP and SR48968 blocked only [betaAla(8)]-NKA(4-10) responses. SR140333 did not attenuate [betaAla(8)]-NKA(4-10) effects and SR48968 had no effect upon SMSP responses. Carbachol (1 micro M) responses were not altered by any of the three NK antagonists. We conclude that activation of either NK(1) or NK(2) receptors can stimulate epithelial ion transport in human colon mucosa and that the novel dual antagonist, DNK333 may be of potential therapeutic interest in the treatment of IBD and IBS.