Greater resistance to footshock punishment in female C57BL/6J mice responding for ethanol.

BACKGROUND: One characteristic of alcohol use disorder is compulsive drinking or drinking despite negative consequences. When quinine is used to model such aversion-resistant drinking, female rodents typically are more resistant to punishment than males. Using an operant response task where C57BL/6J responded for ethanol mixed with quinine, we previously demonstrated that female mice tolerate higher concentrations of quinine in ethanol than males. Here, we aimed to determine whether this female vulnerability to aversion-resistant drinking behavior is similarly observed with footshock punishment. METHODS: Male and female C57BL/6J mice were trained to respond for 10% ethanol in an operant task on a fixed-ratio three schedule. After consistent responding, mice were tested in a punishment session using either a 0.25 mA or 0.35 milliamp (mA) footshock. To assess footshock sensitivity, a subset of mice underwent a flinch, jump, and vocalize test in which behavioral responses to increasing amplitudes of footshock (0.05 to 0.95 mA) were assessed. In a separate cohort of mice, males and females were trained to respond for 2.5% sucrose and responses were punished using a 0.25 mA footshock. RESULTS: Males and females continued to respond for 10% ethanol when paired with a 0.25 mA footshock. Females alone continued to respond for ethanol when a 0.35 mA footshock was delivered. Both males and females reduced responding for 2.5% sucrose when punished with a 0.25 mA footshock. Footshock sensitivity in the flinch, jump, and vocalize test did not differ by sex. CONCLUSIONS: Females continue to respond for 10% ethanol despite a 0.35 mA footshock, and this behavior is not due to differences in footshock sensitivity between males and females. These results show that female C57BL/6J mice are generally more resistant to punishment in an operant self-administration paradigm. The findings add to the literature characterizing aversion-resistant alcohol-drinking behaviors in females.

Non-fluoroscopic cardiac ablation of neonates with CHD.

In current practice, children with anatomically normal hearts routinely undergo fluoroscopy-free ablations. Infants and children with congenital heart disease (CHD) represent the most difficult population to perform catheter ablation without fluoroscopy. We report two neonatal patients with CHD in whom cardiac ablations were performed without fluoroscopy. The first infant had pulmonary atresia with intact ventricular septum with refractory supraventricular tachycardia, and the second infant presented with Ebstein's anomaly of the tricuspid valve along with persistent supraventricular tachycardia. Both patients underwent uncomplicated, successful ablation without recurrence of arrhythmias. These cases suggest that current approaches to minimising fluoroscopy may be useful even in challenging patients such as neonates with CHD.