Neurochemical evidence that cysteamine modulates amphetamine-induced dopaminergic neuronal activity in striatum by decreasing dopamine release: an in vivo microdialysis study in freely moving rats

Regenerative field effect transistor biosensor for in vivo monitoring of dopamine in fish brains

The detection of dopamine, one of the neurotransmitters in cerebral physiology, is critical in studying brain activities and understanding brain functions. However, regenerative biosensor for monitoring dopamine in the progress of physiological and pathological events is still challenging, due to lack of the platform for repetitive on-line detection-regeneration cycle. Herein, we have developed a regenerated field effect transistor (FET) combined with in vivo monitoring system. In this biosensor, gold-coated magnetic nanoparticles (Fe₃O₄@AuNPs) acts as a regenerated recognition unit for dopamine. Just by simple removal of a permanent magnet, dopamine on the biosensor interface are catalyzed by tyrosinase, thus achieving the regeneration of the biosensor. As a result, this FET biosensor not only reveals high sensitivity and selectivity, but also exhibits excellent stability after 15 regeneration processing. This biosensor is capable of monitor dopamine with a linear range between 1 μmol L^-1 and 120 μmol L^-1 and low detection limit (DL) of 3.3 nmol L^-1. Then, the platform has been successfully applied in dopamine analysis in fish brain under global cerebral cortical neurons. This FET biosensor is the first to on-line and remote control the sensitivity and DL by permanent magnet. It opens the door to reusable, inexpensive and large-scale productions.

Dehydroepiandrosterone increases tonic and phasic dopamine release in the striatum

Dehydroepiandrosterone (DHEA) modulates dopaminergic neurotransmission. It takes part in neurologic and psychiatric diseases involving monoamine neurotransmitters. Earlier results show that DHEA (120-min treatment) reduced striatal dopamine (DA) turnover in rats, suggesting a reduced DA release. Some investigations report that DHEA increases DA release but inhibits motor activity, which seems contradictory. This research examines the effect of DHEA on striatal DA release, its metabolism and motor activity. Male Wistar rats were implanted in the striatum with a cannula for in vivo microdialysis. DHEA was administered (120 mg/kg) and dialysates were collected for 280 min. A depolarizing stimulus was applied at 120 min. Samples were analyzed by HPLC-ED to determine the concentration of DA and its metabolites. The effect of DHEA on motor activity was also evaluated during 120 min. Extracellular DA concentration was greater in treated animals both before and after depolarization. In contrast, DHEA reduced the areas below the curves for DA metabolites and DA/metabolite ratios. DHEA also reduced motor activity, remarkably in the first 20 min after treatment. In summary, DHEA yielded a stimulatory effect on striatal DA release that was not reflected in neither DA metabolism nor motor activity. Thus, DHEA resembles the effect of typical antipsychotics, increasing DA release but reducing behavioral activation.

Therapeutic Applications of Cysteamine and Cystamine in Neurodegenerative and Neuropsychiatric Diseases

Current medications for neurodegenerative and neuropsychiatric diseases such as Alzheimer's disease (AD), Huntington's disease (HD), Parkinson's disease (PD), and Schizophrenia mainly target disease symptoms. Thus, there is an urgent need to develop novel therapeutics that can delay, halt or reverse disease progression. AD, HD, PD, and schizophrenia are characterized by elevated oxidative and nitrosative stress, which play a central role in pathogenesis. Clinical trials utilizing antioxidants to counter disease progression have largely been unsuccessful. Most antioxidants are relatively non-specific and do not adequately target neuroprotective pathways. Accordingly, a search for agents that restore redox balance as well as halt or reverse neuronal loss is underway. The small molecules, cysteamine, the decarboxylated derivative of the amino acid cysteine, and cystamine, the oxidized form of cysteamine, respectively, mitigate oxidative stress and inflammation and upregulate neuroprotective pathways involving brain-derived neurotrophic factor (BDNF) and Nuclear factor erythroid 2-related factor 2 (Nrf2) signaling. Cysteamine can traverse the blood brain barrier, a desirable characteristic of drugs targeting neurodegeneration. This review addresses recent developments in the use of these aminothiols to counter neurodegeneration and neuropsychiatric deficits.