CULTURED NEURONS FROM MOUSE-BRAIN REPRODUCE THE MUSCARINIC RECEPTOR PROFILE OF THEIR TISSUE OF ORIGIN

These studies investigate the regional variations in the muscarinic acetylcholine receptor (mAChR) profiles in neuron populations of the CNS using primary neuron cultures derived from three areas of the mouse brain-the cerebral hemispheres, the mesencephalon and the medulla-pons-that have distinct mAChR systems. We first assessed the extent to which neurons reproduced their in vivo properties in culture by monitoring the binding capacity, the pharmacological profiles and the levels of mAChR transcripts in neuron cultures and their tissues of origin. We showed that the primary neuron cultures accumulated mAChRs with initial rates similar to those in vivo, had pharmacological profiles very close to those of their area of origin, and accumulated m1, m2, m3, m4 and m5 receptor transcripts according to patterns resembling those in the tissues. We conclude that most of the characteristics of the mAChRs in a given area are proper to the neuron population of that area, that the pattern is established early in ontogenesis, and that it is reproduced in vitro. We also show that the stimulation of phosphoinositide turnover is mediated by mAChRs with distinct pharmacological profiles in neuron cultures from the three brain areas.