Biology subjects

Kalelkar, A.

Publications and source records attributed to Kalelkar, A..

3 recordsLinked to original sources

bioRxiv2026

Dorsal striatal circuit mechanisms contributing to astrocyte modulation of alcohol-related behaviors

BackgroundThe dorsolateral striatum (DLS) is a key site for coordinating the alcohol-induced stimulant response, a behavioral marker predictive of future alcohol use disorder. Although ethanol (EtOH) affects all brain cells, little is known about the contribution of non-neuronal DLS cell types to EtOH-induced stimulation. MethodsWe used ex vivo two photon calcium imaging, in vivo fiber photometry of astrocyte and neuronal GCaMP, and astrocyte-specific manipulations in mice to determine DLS astrocyte contributions to EtOH-induced stimulation and voluntary EtOH drinking behavior. Using fiber photometry of GRAB-ACh sensors and cell-type specific chemogenetics, we also assessed the role of cholinergic signaling in observed astrocyte EtOH effects. ResultsAs expected, intraperitoneal EtOH injections (0.5-2g/kg) evoked a stimulant response, evidenced by increased locomotion compared to saline. In parallel, EtOH dose-dependently decreased astrocyte calcium activity but had minimal effects on direct and indirect pathway neuronal activity. Mimicking this reduction with astrocyte-specific expression of CalEX, a calcium extruding pump, facilitated EtOH stimulation compared to mice expressing a control fluorophore. Hence, EtOH-induced suppression of DLS astrocyte activity contributes to stimulation. Astrocyte calcium signaling is a well-known target of neuromodulation. Fiber photometry recordings of extracellular acetylcholine (ACh) levels via GRAB-ACh imaging showed inhibition of ACh release by acute EtOH. We virally expressed the excitatory chemogenetic actuator hM3Dq in striatal cholinergic interneurons to assess whether artificially increasing ACh release blocks EtOH-induced inhibition of astrocytic calcium activity. Despite facilitating ACh release, this manipulation did not impact astrocyte calcium activity under control (saline) or EtOH conditions. Together, this work identifies DLS astrocytes as key contributors to EtOH-induced stimulation and highlights the importance of considering astrocyte-neuron interactions in evaluating alcohol effects.

neuroscience↗

bioRxiv2024

A cortical locus for modulation of arousal states

Fluctuations in global arousal are key determinants of spontaneous cortical activity and function. Several subcortical structures, including neuromodulatory nuclei like the locus coeruleus (LC), are involved in the regulation of arousal. However, much less is known about the role of cortical circuits that provide top-down inputs to arousal-related subcortical structures. Here, we investigated the role of a major subdivision of the prefrontal cortex, the anterior cingulate cortex (ACC), in arousal modulation. Pupil size, facial movements, heart rate, and locomotion were used as non-invasive measures of arousal and behavioral state. We designed a closed loop optogenetic system based on machine vision and found that real time inhibition of ACC activity during pupil dilations suppresses ongoing arousal events. In contrast, inhibiting activity in a control cortical region had no effect on arousal. Fiber photometry recordings showed that ACC activity scales with the magnitude of spontaneously occurring pupil dilations/face movements independently of locomotion. Moreover, optogenetic ACC activation increases arousal independently of locomotion. In addition to modulating global arousal, ACC responses to salient sensory stimuli scaled with the size of evoked pupil dilations. Consistent with a role in sustaining saliency-linked arousal events, pupil responses to sensory stimuli were suppressed with ACC inactivation. Finally, our results comparing arousal-related ACC and norepinephrinergic LC neuron activity support a role for the LC in initiation of arousal events which are modulated in real time by the ACC. Collectively, our experiments identify the ACC as a key cortical site for sustaining momentary increases in arousal and provide the foundation for understanding cortical-subcortical dynamics underlying the modulation of arousal states.

neuroscience↗

bioRxiv2023

A paradigm for ethanol consumption in head-fixed mice during prefrontal cortical two-photon calcium imaging

The prefrontal cortex (PFC) is a hub for higher-level cognitive behaviors and is a key target for neuroadaptations in alcohol use disorders. Preclinical models of ethanol consumption are instrumental for understanding how acute and repeated drinking affects PFC structure and function. Recent advances in genetically encoded sensors of neuronal activity and neuromodulator release combined with functional microscopy (multiphoton and one-photon widefield imaging) allow multimodal in-vivo PFC recordings at subcellular and cellular scales. While these methods could enable a deeper understanding of the relationship between alcohol and PFC function/dysfunction, they require animals to be head-fixed. Here, we present a method in mice for binge-like ethanol consumption during head-fixation. Male and female mice were first acclimated to ethanol by providing home cage access to 20% ethanol (v/v) for 4 or 8 days. After home cage drinking, mice consumed ethanol from a lick spout during head-fixation. We used two-photon calcium imaging during the head-fixed drinking paradigm to record from a large population of PFC neurons (>1000) to explore how acute ethanol affects their activity. Drinking modulated activity rates in a subset of neurons on slow (minutes) and fast (seconds) time scales but the majority of neurons were unaffected. Moreover, ethanol intake did not significantly affect network level interactions in the PFC as assessed through inter-neuronal pairwise correlations. By establishing a method for binge-like drinking in head-fixed mice, we lay the groundwork for leveraging advanced microscopy technologies to study alcohol-induced neuroadaptations in PFC and other brain circuits. HighlightsO_LIC57BL/6J mice voluntarily consume ethanol to binge-like levels during head-fixation, with females consuming more ethanol than males. C_LIO_LIMice show differences in frontloading and licking behavior for head-fixed ethanol and sucrose consumption. C_LIO_LIHead-fixed paradigm enables two-photon calcium imaging in the anterior cingulate cortex subdivision of the prefrontal cortex. C_LIO_LIAcute ethanol increases and decreases single neuron activity at fast (seconds) and slow (minutes) time scales but does not alter pairwise correlations between neurons. C_LI

neuroscience↗