Micro-needle electrode for real-time monitoring of norepinephrine in rat central nervous system

Abstract

Norepinephrine (NE) is an important neurotransmitter in the body, and stress or injury of neurons in the locus ceruleus (LC) results in the change of NE level in the body. In this work, we developed a micro-needle electrode for real-time monitoring of NE release in rat brain LC and investigating the effects of alpha 2-adrenoceptors on norepinephrine release upon LC stimulation by different drugs. The micro-needle electrode was prepared by modified both Au nanotubes (AuNTs) and carbon nanotubes (CNTs) on the substrate of the acupuncture needle (AN). Due to excellent electrochemical performance and biocompatibility of the nanostructures, highly sensitive detection of NE was realized. The results had shown that the CNTs/AuNTs/AN micro-needle was capable of real-time monitoring NE in the linear range from 0.75 μM to 25 μM with the limit of detection of 0.26 μM in the cell culture medium. Moreover, the stainless steel acupuncture needle was easy to be inserted into the tissue for in vivo monitoring NE release in rat brain with minimal damage compared to other electrode materials. The results also demonstrated that alpha 2-adrenoceptors regulated the release of NE in the brain's locus ceruleus. This stable and sensitive micro-needle sensor had the potential application in studying neural signal transmission, which could potentially provide important new insights into the deep brain study as well as the mechanism underlying neurological disease of the nervous system.