Antibody-based electrodes for hormonal and neurotransmitter measurements in vivo

Immunosensors, in which the interaction between an antigen of interest and an antibody can be used for detection purposes, have found multiple uses in biological sciences. Microdialysis techniques provide a format for samplin g, with low invasiveness, from circulation and tissues of conscious animals . We have combined these two designs to construct antibody-based electrodes housed within microdialysis probes that allow 'relative' real-time measure ments of several hormones and putative neurotransmitters in vivo. Measureme nts of two hormones, prolactin and oxytocin, were made from areas of the br ain, by using a combination imummunosensor microdialysis techniques, in beh aving sheep. Sensors were viable for between 200 and 400 sequential measure s and for at least 6 hours in vivo. Detection sensitivity was between 1 and 2 pg/mL. The results suggest the possibility of monitoring these nuerohumo ral factors within the blood, or organ systems, of conscious behaving anima ls.