Project Details
Projekt
Assessment of larval methylphenidate (Ritalin) exposure in the differentiating zebrafish brain by non-invasive analysis using a microfluidic chip
Subject Area
Biomedical Systems Technology
Term
since 2019
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 427719460
The amphetamine-derivate Methylphenidate (MPH) acts as agonist for dopaminergic neurons. MPH reduces impulsivity and promotes the ability to concentrate without severe addiction potential. Therefore, MPH is considered a save therapeutic medication against attention deficit hyperactivity syndrome (ADHS) or internet gaming disorder (IGD). MPH is prescribed as medication (Ritalin, Concerta) to a large number of young children, but it is also often overdosed as recreational performance-enhancing drug. However, the influence of MPH on brain-wide neural circuit activity and lasting effects are barely understood. We have recently designed a microfluidic chip for chemically stimulating and recording whole-brain activity at cellular resolution from zebrafish larvae in a non-invasive manner. Since this chip was fabricated entirely from glass, it is not compromised by autofluorescence or drug absorption. In parallel, automated image analysis routines for the obtained large microscopy datasets were established and allowed to evaluate the response of the zebrafish brain to amphetamine exposure. Of note, forebrain dopaminergic neurons were among the earliest responding neuronal populations followed by specific neuronal populations largely involving the hindbrain. Preliminary data obtained from MPH-stimulated larvae revealed amphetamine-related stimulation patterns yet as expected with later activation onset and lower intensity. Thus, longer image recording protocols ideally under oxygen monitoring conditions will be required for evaluating MPH-stimulated brain-wide neuronal activity. BIO-133 is a biocompatible transparent polymer with a low refraction index close to water. This material could substitute glass, while maintaining the superior optical properties of the chip. Furthermore, BIO-133 allows for the incorporation of sensors to functionalize microfluidic chips for multi-modal data acquisition. We aim to establish a low refraction index (LowRI) NeuroExaminer chip made from Bio-133 with the help of two-photon-polymerization. It will be equipped with miniaturized oxygen sensors for maintaining normoxic conditions during prolonged zebrafish larval brain activity recording. Amphetamine and MPH-stimulated whole brain activity patterns will be compared to identify identical and different neuronal populations stimulated by these related compounds. Both drugs will likely activate amygdala neurons early, while neurons of the cerebellum have been reported to be stimulated by MPH, which we could not observe upon amphetamine stimulation. Furthermore, to investigate lasting effects of MPH stimulation, we will monitor brain-wide neuronal activity in zebrafish larvae 18 hours after termination of MPH exposure or during long-term recording lasting several hours under normoxic conditions. These studies will provide critical insight into MPH-mediated acute and lasting modulation of neuronal activity, knowledge important for dosing, drug safety and quality control.
DFG Programme
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