[Ontogenesis of anesthesia-relevant receptors]

Abstract

The particularities in the medical treatment of children, especially those concerning premature infants, new-borns and babies, do not only stem from the immaturity of the organs (kidneys, liver etc.) but also from pharmacokinetic factors which are result of the immaturity of the brain. There are maturation deficits on all levels of transmission, from the nerve with electric transmission to the synapsis with neurotransmitter propagation, even though the whole system is basically laid out. The presented paper concerns itself mainly with the ontogenesis of the receptor-systems, a small part is dedicated to the question of myelination. Number and distribution of the receptors in premature or new-born infants and babies should not only be viewed in the context of the future function in mature humans (i.e. transmission and modification of information) - the receptors themselves are important factors in the maturing process of neuronal pathways, synapses and the differentiation of the neuronal cells themselves. Basically the number of receptors can change as follows: 1. Continuous increase until maturity, 2. Increase to a maximum during maturation with slight or stronger decrease after, 3. High initial number with following distinct decrease, 4. Even number throughout maturation, 5. Passing expression during maturation. The aim of this paper is to present an overview on the ontogenesis of opioid-, NMDA-, GABA-, dopamine-, acetylcholine- and serotoninreceptors. The data derived from animal and human-pharmacological experiments will be used to carefully conclude how the particularities of drug reactions of children (i.e. increased respiratory depression after opioid application in premature and newborn infants, higher incidence of paradox reactions to benzodiazepines etc.) can be explained.