Key result
Metoprolol, but not atenolol, reduced the prolonged effects of emotional stress, including increased plasma NPY levels, increased arterial pressure, and reduced cardiac vagal activation in pigs.
Why the study?
Does metoprolol reduce stress-induced neuropeptide Y release and cardiovascular responses compared to atenolol in pigs?
RCT
Randomized crossover
Does metoprolol reduce stress-induced neuropeptide Y release and cardiovascular responses compared to atenolol in pigs?
Central nervous system penetration by lipophilic beta-blockers like metoprolol may be required to prevent prolonged sympathetic activation and neuropeptide Y release following emotional stress.
Supports lipophilic beta-blocker investigation for stress responses in models; leaves open human translation and clinical relevance.
OBJECTIVES: To explore if β-adrenergic receptors in the brain are involved in acute and delayed cardiovascular responses to a brief emotional stress, by comparing the effects of the β1-blockers metoprolol (lipophilic) and atenolol (hydrophilic). DESIGN: Male dominant pigs, singleliving, freely moving, with telemetric recordings of intra-arterial pressure and ECG and assay of plasma levels of the adrenergic cotransmitter neuropeptide Y (NPY), were confronted with four alien pigs for three minutes at weekly intervals. Weeks 1 and 4 were controls, in weeks 2 and 3 randomized crossover treatment with metoprolol or atenolol were given. RESULTS: The confrontation caused instant and transient tachycardia and more prolonged effects in terms of increased plasma NPY levels, increased arterial pressure and reduced cardiac vagal activation. The two β-blockers inhibited the tachycardia equally, but only metoprolol reduced the prolonged effects. CONCLUSIONS: Emotionally induced sympathetic activation involves peripheral release of NPY causing a prolonged increase of arterial pressure and a reduction of cardiac vagal activity. These effects are prevented by central nervous β-adrenoceptor blockade.
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Åblad et al. (2010) conducted an RCT in Stress-induced cardiovascular responses. Metoprolol vs. Atenolol was evaluated on Cardiovascular responses (tachycardia, plasma NPY levels, arterial pressure, cardiac vagal activation). Metoprolol, but not atenolol, reduced the prolonged effects of emotional stress, including increased plasma NPY levels, increased arterial pressure, and reduced cardiac vagal activation in pigs.
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