Genetically encoded sensors for measuring histamine release both in vitro and in vivo

Abstract

Histamine (HA) is a key biogenic monoamine involved in a wide range of physiological and pathological processes in both the central nervous system and the periphery. Because the ability to directly measure extracellular HA in real-time will provide important insights into the functional role of HA in complex circuits under a variety of conditions, we developed a series of genetically encoded G protein-coupled receptor activation-based (GRAB) HA (GRABHA) sensors. These sensors produce a robust increase in fluorescence upon HA application, with good photostability, sub-second kinetics, nanomolar affinity, and high specificity. Using these GRABHA sensors, we measured electrical stimulation-evoked HA release in acute brain slices with high spatiotemporal resolution. Moreover, we recorded HA release in the preoptic area of the hypothalamus and in the medial prefrontal cortex during the sleep-wake cycle in freely moving mice, finding distinct patterns of HA release in these specific brain regions. Together, these in vitro and in vivo results show that our GRABHA sensors have high sensitivity and specificity for measuring extracellular HA, thus providing a robust new set of tools for examining the role of HA signaling in both health and disease.

Novel genetically encoded tools for imaging or silencing neuropeptide release from presynaptic terminalsin vivo

“…Our CybSEP2 system: 1) can pinpoint exactly where the neuropeptides are released from, 2) can be used to monitor essentially any neuropeptide by driving the expression of CybSEP2 via a neuropeptide-specific Cre-driver mouse line, and 3) does not interfere with endogenous peptidergic signaling. Given the fact that only a handful of GPCR-based neuropeptide sensors are currently available (Dong et al, 2022; Qian et al, 2022; Wang et al, 2022), CybSEP2 can serve as an alternative tool for monitoring the release of neuropeptides for which postsynaptic sensors are not yet available. However, this versatility limits the specificity of the CybSEP2 system.…”

An octopamine-specific GRAB sensor reveals a monoamine relay circuitry that boosts aversive learning

“…To monitor octopamine (OA) release in vivo with high specificity, sensitivity and spatiotemporal resolution, we employed a well-established strategy [42][43][44][45][46][47][48][49][50][51][52][53] to develop a genetically encoded GPCR activation-based (GRAB) sensor for OA using EGFP to report an increase in extracellular OA through an increase in fluorescence intensity.…”

Monitoring norepinephrine releasein vivousing next-generation GRABNEsensors

“…Genetically encoded GRABNE sensors can also be used to examine the spatiotemporal dynamics of NE release in the brain, which is a tightly regulated, complex process that can depend on a variety of factors such as the state of arousal and the activation of distinct brain regions. Moreover, previous studies suggested that specific brain regions may have either similar or distinct patterns of neurotransmitter release during the sleep-wake cycle [24][25][26] . To measure the dynamics of NE release in specific brain regions and determine whether this release is synchronized between brain regions, we utilized expressed GRABNE2m to simultaneously monitor NE levels in both the medial prefrontal cortex (mPFC) and the preoptic area of the hypothalamus (POA) (Figure 4A), two brain regions critically involved in regulating arousal and wakefulness.…”