RESUMO
The testicular feminized (Tfm) mouse carries a nonfunctional androgen receptor (AR) and reduced circulating testosterone levels. We used Tfm and castrated mice to determine whether testosterone modulates markers of aging in cardiomyocytes via its classic AR-dependent pathway or conversion to estradiol. Male littermates and Tfm mice were divided into 6 experimental groups. Castrated littermates (group 1) and sham-operated Tfm mice (group 2, N = 8 each) received testosterone. Sham-operated Tfm mice received testosterone in combination with the aromatase inhibitor anastrazole (group 3, N = 7). Castrated littermates (group 4) and sham-operated untreated Tfm mice (group 5) were used as controls (N = 8 and 7, respectively). An additional control group (group 6) consisted of age-matched non-castrated littermates (N = 8). Cardiomyocytes were isolated from the left ventricle, telomere length was measured by quantitative PCR and expression of p16INK4α, retinoblastoma (Rb) and p53 proteins was detected by Western blot 3 months after treatment. Compared with group 6, telomere length was short (P < 0.01) and expression of p16INK4α, Rb and p53 proteins was significantly (P < 0.05) up-regulated in groups 4 and 5. These changes were improved to nearly normal levels in groups 1 and 2 (telomere length = 0.78 ± 0.05 and 0.80 ± 0.08; p16INK4α = 0.13 ± 0.03 and 0.15 ± 0.04; Rb = 0.45 ± 0.05 and 0.39 ± 0.06; p53 = 0.16 ± 0.04 and 0.13 ± 0.03), but did not differ between these two groups. These improvements were partly inhibited in group 3 compared with group 2 (telomere length = 0.65 ± 0.08 vs 0.80 ± 0.08, P = 0.021; p16INK4α = 0.28 ± 0.05 vs 0.15 ± 0.04, P = 0.047; Rb = 0.60 ± 0.06 vs 0.39 ± 0.06, P < 0.01; p53 = 0.34 ± 0.06 vs 0.13 ± 0.03, P = 0.004). In conclusion, testosterone deficiency contributes to cardiomyocyte aging. Physiological testosterone can delay cardiomyocyte aging via an AR-independent pathway and in part by conversion to estradiol.
Assuntos
Animais , Masculino , Camundongos , Envelhecimento/metabolismo , Senescência Celular/fisiologia , Estradiol/metabolismo , Miócitos Cardíacos/fisiologia , Receptores Androgênicos/metabolismo , Testosterona/farmacologia , Envelhecimento/patologia , Biomarcadores/análise , /efeitos dos fármacos , Modelos Animais , Orquiectomia , Distribuição Aleatória , Proteína do Retinoblastoma/metabolismo , Encurtamento do Telômero/efeitos dos fármacos , Testosterona/deficiência , /metabolismoRESUMO
The testicular feminized (Tfm) mouse carries a nonfunctional androgen receptor (AR) and reduced circulating testosterone levels. We used Tfm and castrated mice to determine whether testosterone modulates markers of aging in cardiomyocytes via its classic AR-dependent pathway or conversion to estradiol. Male littermates and Tfm mice were divided into 6 experimental groups. Castrated littermates (group 1) and sham-operated Tfm mice (group 2, N = 8 each) received testosterone. Sham-operated Tfm mice received testosterone in combination with the aromatase inhibitor anastrazole (group 3, N = 7). Castrated littermates (group 4) and sham-operated untreated Tfm mice (group 5) were used as controls (N = 8 and 7, respectively). An additional control group (group 6) consisted of age-matched non-castrated littermates (N = 8). Cardiomyocytes were isolated from the left ventricle, telomere length was measured by quantitative PCR and expression of p16INK4α, retinoblastoma (Rb) and p53 proteins was detected by Western blot 3 months after treatment. Compared with group 6, telomere length was short (P < 0.01) and expression of p16INK4α, Rb and p53 proteins was significantly (P < 0.05) up-regulated in groups 4 and 5. These changes were improved to nearly normal levels in groups 1 and 2 (telomere length = 0.78 ± 0.05 and 0.80 ± 0.08; p16INK4α = 0.13 ± 0.03 and 0.15 ± 0.04; Rb = 0.45 ± 0.05 and 0.39 ± 0.06; p53 = 0.16 ± 0.04 and 0.13 ± 0.03), but did not differ between these two groups. These improvements were partly inhibited in group 3 compared with group 2 (telomere length = 0.65 ± 0.08 vs 0.80 ± 0.08, P = 0.021; p16INK4α = 0.28 ± 0.05 vs 0.15 ± 0.04, P = 0.047; Rb = 0.60 ± 0.06 vs 0.39 ± 0.06, P < 0.01; p53 = 0.34 ± 0.06 vs 0.13 ± 0.03, P = 0.004). In conclusion, testosterone deficiency contributes to cardiomyocyte aging. Physiological testosterone can delay cardiomyocyte aging via an AR-independent pathway and in part by conversion to estradiol.
Assuntos
Envelhecimento/metabolismo , Senescência Celular/fisiologia , Estradiol/metabolismo , Miócitos Cardíacos/fisiologia , Receptores Androgênicos/metabolismo , Testosterona/farmacologia , Envelhecimento/patologia , Animais , Biomarcadores/análise , Genes p16/efeitos dos fármacos , Masculino , Camundongos , Modelos Animais , Orquiectomia , Distribuição Aleatória , Proteína do Retinoblastoma/metabolismo , Encurtamento do Telômero/efeitos dos fármacos , Testosterona/deficiência , Proteína Supressora de Tumor p53/metabolismoRESUMO
We have previously demonstrated that 1,25-dihydroxyvitamin D3 decreases endotoxin-induced mortalities of rat and mouse from 80% and 70% to 14% and 10% (unpublished results). In the present study, pretreatment of 1,25-dihydroxyvitamin D3 decreased pad oedema and pulmonary vascular permeability induced by scalding and platelet-activating factor. 1,25-Dihydroxyvitamin D3 in a dose of 4 x 10(-9) mol/kg decreased pulmonary extravascular Evans blue concentration increased by platelet-activating factor from 6.32 +/- 0.63 ng/g to 2.57 +/- 0.28 ng/g (P < 0.01), and lung water/dry lung weight from 3.79 +/- 0.57 to 1.51 +/- 0.13 (P < 0.01). 1,25-Dihydroxyvitamin D3 of 4 x 10(-11) moles/kg and calcipotriol (a vitamin D analogue which has limited hypercalcaemic effect) of 4 x 10(-9) moles/kg had similar effects. Karyocyte counting of bronchoalveolar lavage fluid and the reduction of mean arterial pressure were also reduced to some extent. These results suggest that 1,25-dihydroxyvitamin D3 may be a new and effective drug to reduce vascular permeability and ameliorate oedema.
