Electrochemica Technique Of Dopamine Release And Study In Vivo

Information communication in central nervous system (CNS) depends on synaptic transmission mainly mediated by presynaptic neurotransmitter release, which plays a crucial role in normal brain function. Real-time measurement of neurotransmitter release in brain is very important to study the mechanisms in which abnormality of neurotrnsmitter release leads to that of brain function. Carbon fiber microelectrode (CFE ) with electrochemical technique in vivo is employed to measure easily oxidized substances including noradrenaline, adrenaline and dopamine (DA) belonging to catecholamine. DA is an important neurotransmitter in CNS, which is released by DAnergic terminals distributing in striatum, nucleus accumbens, hippocampus and medial prefrontal cortex etc. DA cell bodys locate in substantia nigra and ventral tegmental area. DA is closely related with many normally physiological functions including movement, learning and memory, mood and reward. The abnormality of DA release is a critical cause of many kinds of nerve and psychiatric diseases, such as Parkinson`s disease, drug addiction, schizophrenia, depression and Huntington`s disease etc.In order to get more efficient, more sensitive CFE to detect DA release in brain, we improved traditional carbon glue-made CFE (C_CFE), and used ethylene glycol monothyl ether (EGME) as conduct material. Compared to C_CFE, EGME-made CFE (Y_CFE) is charaterised by fewer materials to be manufactured conveniently , more stable property of biology, and higher sensitivity, and can be applied to biological experiments.Our previous experiments showed that the complex firing pattern of action potential (AP) defined by a 4-parameter"code function"-F(n,m,f,d) effectively modulated neurotransmitter secretion in rat adrenal chromaffine cells (RACCs), where the four coding parameters (n,m,f,d) were defined as follows, a series of consecutive APs is defined as a"burst";"n"is the number of APs in a burst;"m"is the number of bursts in the whole AP pattern;"f"is the frequency of APs in a burst; and"d"is the interval between two adjacent bursts (when m=1,"d"has no meaning).We found, in addition to AP frequency (f), for a given number of APs, another parameter of the AP code, the number of AP bursts (m) in which the set of APs occurs, effectively modulated cell secretion. However, it is not clear whether"m"effect can effectively modulate neurotransmitter release in vivo.In our study, we stimulated medial forebrain bundle of anaesthetized rats with different AP codes and recorded the real-time DA release in striatum with Y_CFE. On the other hand, we observed DA release in striatum slice, and nucleus accumbens, hippocampus and medial prefrontal cortex in vivo.Our work indicated that, Compared to C_CFE, EGME-made CFE (Y_CFE) is characterized by fewer materials to be manufactured conveniently , more stable property of biology, and higher sensitivity, and can be applied to biological experiments. Measurement of DA release showed that"m"effect effectively modulated DA release and were different with different AP codes in vivo.