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ref: -2014 tags: CNiFER Kleinfeld dopamine norepinephrine monoamine cell sensor date: 10-04-2021 14:50 gmt revision:2 [1] [0] [head]

Cell-based reporters reveal in vivo dynamics of dopamine and norepinephrine release in murine cortex

  • CNiFERs are clonal cell lines engineered to express a specific GPCR that is coupled to the Gq pathway and triggers an increase in intracellular calcium concentration, [Ca2+], which in turn is rapidly detected by a genetically encoded fluorescence resonance energy transfer (FRET)-based Ca2+ sensor. This system transforms neurotransmitter receptor binding into a change in fluorescence and provides a direct and real-time optical readout of local neurotransmitter activity. Furthermore, by using the natural receptor for a given transmitter, CNiFERs gain the chemical specificity and temporal dynamics present in vivo.
    • Clonal cell line = HEK293.
      • Human cells implanted into mice!
    • Gq pathway = through the phospholipase C-initosol triphosphate (PLC-IP3) pathway.
  • Dopamine sensor required the engineering of a chimeric Gqi5 protein for coupling to PLC. This was a 5-AA substitution (only!)

Referenced -- and used by the recent paper Reinforcement learning links spontaneous cortical dopamine impulses to reward, which showed that dopamine signaling itself can come under volitional, operant-conditioning (or reinforcement type) modulation.

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ref: -0 tags: concentation of monoamine dopamine serotonin and norepinephrine in the brain date: 04-28-2016 19:38 gmt revision:3 [2] [1] [0] [head]

What are the concentrations of the monoamines in the brain? (Purpose: estimate the required electrochemical sensing area & efficiency)

  • Dopamine: 100 uM - 1 mM local, extracellular.
    • PMID-17709119 The Yin and Yang of dopamine release: a new perspective.
  • Serotonin (5-HT): 100 ng/g, 0.5 uM, whole brain (not extracellular!).
  • Norepinephrine / noradrenaline: 400 nm/g, 2.4 uM, again whole brain.
    • PMID-11744005 An enriched environment increases noradrenaline concentration in the mouse brain.
    • Also has whole-brain extracts for DA and 5HT, roughly:
      • 1200 ng/g DA
      • 400 ng/g NE
      • 350 ng/g 5-HT
  • So, one could imagine ~100 uM transient concentrations for all 3 monoamines.