Expression of a heroin contextually conditioned immune effect in male rats requires CaMKIIα-expressing neurons in dorsal, but not ventral, subiculum and hippocampal CA1

Abstract

The physiological and motivational effects of heroin and other abused drugs become associated with environmental (contextual) stimuli during repeated drug use. As a result, these contextual stimuli gain the ability to elicit drug-like conditioned effects. For example, after context-heroin pairings, exposure to the heroin-paired context alone produces similar effects on peripheral immune function as heroin itself. Conditioned immune effects can significantly exacerbate the adverse health consequences of heroin use. Our laboratory has shown that exposure to a heroinpaired context suppresses lipopolysaccharide (LPS)-induced splenic nitric oxide (NO) production in male rats, and this effect is mediated in part by the dorsal hippocampus (dHpc). However, specific dHpc output regions, whose efferents might mediate conditioned immune effects, have not been identified, nor has the contribution of ventral hippocampus (vHpc) been investigated. Here, we evaluated the role of CaMKIIα-expressing neurons in the dHpc and vHpc main output regions by expressing G i -coupled designer receptors exclusively activated by designer drugs (DREADDs) under a CaMKIIα promoter in the dorsal subiculum and CA1 (dSub, dCA1) or ventral subiculum and CA1 (vSub, vCA1). After context-heroin conditioning, clozapine-N-oxide (CNO, DREADD agonist) or vehicle was administered systemically prior to heroin-paired context (or home-cage control) exposure and LPS immune challenge. Chemogenetic inhibition of CaMKIIα-expressing neurons in dHpc, but not vHpc, output regions attenuated the expression of conditioned splenic *

Selective inhibition of excitatory synaptic transmission alters the emergent bursting dynamics of in vitro neural networks

“…However, these approaches indiscriminately block NMDA and AMPA receptors potentially expressed in inhibitory interneurons and some glia cells ( Hestrin, 1993 ; Geiger et al, 1995 ; Verkhratsky and Kirchhoff, 2007 ; Perez-Rando et al, 2017 ). In this study, we utilized hM4Di designer receptors exclusively activated by designer drugs (DREADDs) ( Armbruster et al, 2007 ; Alexander et al, 2009 ; Urban and Roth, 2015 ; Khambhati and Bassett, 2016 ; Whissell et al, 2016 ; Panthi and Leitch, 2019 ; Haaranen et al, 2020a , b ; Lebonville et al, 2020 ; Ozawa and Arakawa, 2021 ) to selectively inhibit excitatory synaptic transmission— via G-protein coupled receptors (GPCRs) in calcium/calmodulin-dependent protein kinase alpha (CaMKlla) expressing neurons—in neural networks interfaced with microelectrode arrays (MEAs). This method allows us to target and manipulate excitatory synaptic transmission with greater selectivity while minimizing unintended off-target effects.…”

Chronic ethanol consumption exacerbates future stress‐enhanced fear learning, an effect mediated by dorsal hippocampal astrocytes

“…Tissue for RT‐qPCR was prepared as described previously (Lebonville et al, 2020; Paniccia et al, 2018, 2021), with modifications made in the RNA extraction step. Briefly, brain tissue punches were homogenized (Precellys Instruments) and BCP (1‐Bromo‐3‐Chloropropane; Molecular Research Center) was added to homogenate for phase separation.…”

“…Tissue for RT-qPCR was prepared as described previously (Lebonville et al, 2020;Paniccia et al, 2018Paniccia et al, , 2021 for 20 s with data collection at the end of each cycle. Data were analyzed using the comparative CT (ΔΔCΤ) method.…”

Selective inhibition of excitatory synaptic transmission alters the emergent bursting dynamics of in vitro neural networks

“…Methods such as pharmacological blockade of NMDA and AMPA receptors (Chub and O’Donovan, 1998, Li et al, 2007, Suresh et al, 2016) and membrane current blockers (Ramakers et al, 1990, Ramakers et al, 1994, van Drongelen et al, 2006) have provided significant insights into the functional contribution of synaptic receptors and intrinsic membrane currents to the generation, maintenance, duration, and propagation of network bursts. In this study, we utilized hM4Di designer receptors exclusively activated by designer drugs (DREADDs) (Armbruster et al, 2007, Alexander et al, 2009, Urban and Roth, 2015, Khambhati and Bassett, 2016, Whissell et al, 2016, Panthi and Leitch, 2019, Haaranen et al, 2020a, Haaranen et al, 2020b, Lebonville et al, 2020, Ozawa and Arakawa, 2021) to selectively inhibit excitatory synaptic transmission – via G-protein coupled receptors (GPCRs) in calcium/calmodulin-dependent protein kinase alpha (CaMKlla) expressing neurons – in neural networks interfaced with microelectrode arrays (MEAs). Networks were chemogenetically inhibited at 14 DIV, 21 DIV and 28 DIV and their dynamics characterized in comparison to their baseline activity and to PBS vehicle and control, unperturbed networks.…”