RESEARCH

Mario_RaggenbassBW.jpgIn the brain, fast synaptic transmission is mediated by neurotransmitters which exert their excitatory or inhibitory effects by acting on postsynaptic ionotropic receptors. In addition, central neurons synthesize, release and are affected by neuromodulators, the function of which is to regulate the responsiveness of postsynaptic neurons to fast neurotransmitters. A variety of compounds (e.g. neuropeptides, catecholamines, cholinergic agonists) can play a role as neuromodulators. They do so by acting on metabotropic receptors (e.g. neuropeptide receptors) or ionotropic receptors (e.g. nicotinic acetylcholine receptors). Our aim is to investigate the mechanism of action of selected neuromodulators in central neuronal circuits. We use advanced electrophysiological recordings and Ca ++ measurement techniques. As preparations, we use brain slices or organotypic cultures of neuronal tissue. We are currently interested in the following research themes: i) Action of vasopressin on brainstem and spinal motor circuits. ii) Action of tachykinins in hippocampal circuits. iii) Effects of nicotinic agonists in the endocrine hypothalamus and in autonomic centers of the spinal cord. The influence that these compounds exert on specific neuronal networks probably constitute the neurobiological substrate responsible of their effects on more integrative brain functions, like autonomic regulation, motor control and cognition. Our cellular neurophysiological approach, coupled to morphological, physiological, genetic and behavioral investigations carried out in other laboratories, should contribute to an understanding of the role of neuromodulators in the brain.