Caffeine excites medial parabrachial nucleus neurons of mice by blocking adenosine A1 receptor

Abstract

Caffeine has been used as a first-line drug for treatment of apnea neonatorum for decades due to its high safety and effectiveness. Studies report that caffeine mainly acts as a blocker of Adenosine Receptors (ARs). However, the mechanism of caffeine in reducing apnea neonatorum in the central nervous system has not been fully explored. Medial parabrachial nucleus (MPB) is part of the respiratory center of the pons that may be related to the activity of caffeine. Previous studies have not explored the effect and mechanism of caffeine on MPB neurons. To elucidate this, the current study used antagonists of A1 and A2a receptors to mimic the effect of caffeine in MPB of mice in vitro using the patch-clamp technique. The firing rates and spontaneous post-synaptic currents were recorded. The findings of the study showed that caffeine excited MPB neurons. Notably, the adenosine A1R antagonist 8-cyclopentyl-1,3-dimethyl-xanthine (CPT) but not the adenosine A2aR antagonist Istradefylline (KW6002) mimicked the exciting effect of caffeine, implying that caffeine excited MPB neurons in mice by blocking A1Rs. Further, the results indicated that caffeine could increase efficiency of synaptic transmission to excite MPB neurons. These findings suggest that A1Rs in MPB may be potential targets for caffeine in reducing apnea neonatorum.