EFFECT OF E2 ON CONNEXIN40 (CX40) MRNA EXPRESSION IN VITRO AND IN VIVO

• Published in: Animal biology journal Vol. 4; no. 4; p. 254
• Main Authors: Oliveira, T M, Faustino, L C, Zeca, S G, Rangel, N D A L, Pazos-Moura, C C, Almeida, N A S
• Format: Journal Article
• Language: English
• Published: Hauppauge Nova Science Publishers, Inc 01.10.2013
• Subjects: Rodents
• ISSN: 1949-498X

The main estrogen, 17beta-estradiol (E2), plays important regulatory functions in a wide variety of biological processes, including cardiac functions. The propagation of electrical activity in myocardium depends on the transfer of current at gap junctions and Connexins 40 and 43 are the predominant junctional proteins. In mice, Cx40 is restricted to the atrium and conduction system. It is unknown whether E2 regulates atrium Cx. Here we evaluated the effect of E2 benzote on the atrium expression of Cx40 mRNA in correlation with ECG studies and in vitro experiments were performed. Female mice was submitted to bilateral ovariectomy, and after a 2-week recover, the OVX mice were injected with 2 (OVX+2BE) or 20 (OVX+20BE) ug/kg body weight of E2 benzoate (Sigma) daily for 15 days and then ECG analyses were performed. A7r5 cells were treated with E2 benzoate (10-8 and 10-6 M) for 24 hours. Cx40 mRNA was evaluated by q-PCR using specific primers for Cx and 36beta4, and p < 0.05 was considered statistically significant. The OVX+20BE group presented a prolonged PR interval (30%) and the P wave duration was increased by 30% compared to the OVX group (n = 6 animals per group). The atrium Cx40 mRNA level decreased 25% compared to the OVX group. No change was observed in the Cx40 mRNA expression of the A7r5 cells treated with 10-8 M of E2 benzoate, however, the Cx mRNA was lower in the A7r5group treated with 10-6 M. These data suggest that E2 regulate the Cx40 mRNA at higher doses, therefore, slow velocity of electrical conduction in atrium myocardial cells in the OVX+20BE group can be attributed, at least in part, to the reduced expression of atrium Cx40.