Localization of the cardiac ganglion in chasmagnathus. Gabaergic regulation

YANG MARGARITA; CARBÓ MARTÍN; FREUDENTHAL RAMIRO; HERMITTE GABRIELA

Huerta Grande

Congreso; IIRCN Second Joint Meeting of the Argentine Society for Neuroscience (SAN: XXV Reunión Anual de la Sociedad Argentina de Investigación en Neurociencias) and the Argentine Workshop in Neuroscience (TAN: XII Taller Argentino de Neurociencias); 2010

IIRCSociedad Argentina de Investigación en Neurociencias) and the Argentine Workshop in Neurosci

Decapod heart contains a cardiac ganglion that consists of a few neurons supplied by inhibitory and excitatory inputs from the central nervous system. Heartbeat is inhibited by the application of GABA and cardiac inhibition induced by inhibitory neural processes activation is blocked by picrotoxin. Cardio inhibitory processes show GABA immunoreactivity. Bradycardia or reversible heart arrests have been reported in decapods to a variety of stimuli. Our objective is to study the regulatory neural substrate of this inhibitory cardiac response in the crab Chasmagnathus. The aim is to localize the cardiac ganglion, identify probable regulatory neurotransmitters and record heart rate during training in the presence of GABA antagonists. We investigated the cardiac system in the crab by means of a latex vascular filling technique that allowed the delineation of the arterial system. Next, we localized the crab cardiac ganglion by histology, finding a discrete zone where a few neurons can be easily visualized. Further on we obtained GABA immunoreactivity in cardiac tissue. Finally the administration of picrotoxin weakened the heart arrest upon the presentation of visual stimuli. These results point to GABA as an extrinsic inhibitory neurotransmitter involved in this response.