Morphological study of cultured cardiac ganglionic neurons from different postnatal stages of rats

This study sought to establish a culture model of cardiac ganglia (CG) neur ons of the Sprague-Dawley (SD) rat which could by used to study the distinc t characteristics of CG neurons. After culturing, the morphology and immuno cytochemistry of CG neurons obtained on different days after birth were com pared. Samples of CG neurons were taken from the posterior atrial wall of r ats aged 7, 14, 21 and 40 postnatal days (designated as P7, P14, P21 and P4 0, respectively). During 3-6 days of culture, the morphological changes of the cultured neurons were monitored using a light microscope. Immunocytoche mical staining of the neurofilaments (NF-L, -M and -H) was performed to ide ntify the CG neurons and the changes in morphology. The differences in size of the CG soma of each culture were compared by morphometry. Frozen sectio ns of CG neurons were used as the in vivo control of the above experiments. The results showed that the rate of growth in size of the CG soma was high est in the P7 group, and was slower after weaning (21 days after birth). Cu ltured neurons were categorized into unipolar-like (Type I), multipolar-lik e (Type II), and bipolar-like (Type III) based on their morphological chara cteristics. In NF immuocytochemical staining, there were strong responses t o NF-H and NF-M in all cultures, but not to NF-L. More specifically, respon ses to NF-H were mainly observed in perikaryons and neurites, whereas the r esponses to NF-M were mainly in perikaryons. The present study has establis hed a culture system for cardiac ganglia neurons of SD rats. Our results sh ow that the intracardiac neurons were still developing in their somata and the processes and that various responses to different antibodies of NF for CG neurons occurred in different postnatal stages in rats. (C) 2000 Elsevie r Science B.V. All nights reserved.