engleski

Age-related changes in cardiac spinal afferent neurons

Aim: The aim of this study was to explore the effect of aging on the number of spinal afferent neurons projecting to different chambers of the rat heart. Methods: The experiment included 24 female Sprague-Dawley rats divided into two groups-12 young (2 months old) and 12 old (24 months old) rats. We performed an operation using transabdominal approach and applied a patch loaded with retrograde tracer Fast Blue. Each group was divided into four sub-groups according to the chamber of the heart where the patch was placed. The application was made to only one chamber of the heart (left atrium or ventricle, right atrium or ventricle) in all animals belonging to a specific sub-group. Seven days after the surgery animals were sacrificed and the total number of labeled cardiac spinal afferents was counted in dorsal root ganglia bilaterally. Results: The number of neurons projecting to the different chambers of the rat heart decreased significantly (1036 vs. 212) in old rats. However, the relative decrease varied depending on the heart chambers that neurons were projecting to. The smallest decrease was in the population projecting to the right atrium (218 vs. 104), followed by the left atrium (276 vs. 61), the left ventricle (339 vs. 41) and the highest decrease was noticed in neurons projecting to the right ventricle (203 vs. 6). Conclusion: The significant decrease of neuronal number might be one of the factors contributing to the explanation of silent myocardial infarction that occurs in senescence.

spinal afferents; rat; heart innervation; senescence

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