TY - JOUR
T1 - Gq DREADD activation of CaMKIIa MnPO neurons stimulates nitric oxide activity
AU - Marciante, Alexandria B.
AU - Farmer, George E.
AU - Thomas Cunningham, J.
N1 - Funding Information:
This work was supported by National Institutes of Health Grants R01-HL-142341, P01-HL-088052, and T32-AG-020494.
Publisher Copyright:
Copyright © 2020 the American Physiological Society.
PY - 2020
Y1 - 2020
N2 - Designer receptors exclusively activated by designer drugs (DREADDs) modify cellular activity following administration of the exogenous ligand clozapine-N-oxide (CNO). However, some reports indicate CNO may have off-target effects. The current studies investigate the use of Gq DREADDs in CaMKIIa-expressing neurons in the median preoptic nucleus (MnPO). Male Sprague-Dawley rats (250 g) anesthetized with isoflurane were stereotaxically microinjected in the MnPO with the Gq DREADD (AAV5-CaMKIIa-HM3D-mCherry) or control virus (AAV5-CaMKIIa-mCherry). Following a 2-wk recovery, rats were used for either immunohistochemical Fos analysis or in vitro patch-clamp electrophysiology. In Gq DREADD-injected rats, CNO induced significant increases in Fos staining in the MnPO and in regions that receive direct or indirect projections from the MnPO. In electrophysiological studies, CNO depolarized and augmented firing frequency in both Gq DREADD-positive neurons (Gq DREADD) as well as unlabeled MnPO neurons in slices from Gq DREADD-injected rats (Gq DREADDx). Gq DREADDx neurons also displayed increases in spontaneous postsynaptic current (sPSC) frequency in response to CNO. Additionally, CaMKIIa-positive MnPO neurons, which also express nitric oxide synthase (NOS), were treated with N-nitro-L-arginine (L-NNA; competitive inhibitor of NOS) and hemoglobin (NO scavenger) to assess the role of NO in Gq DREADDx neuron recruitment. Both L-NNA and hemoglobin blocked CNO-induced effects in Gq DREADDx neurons without affecting Gq DREADD neurons. These findings indicate that Gq DREADD-mediated activation of CaMKIIa/ NOS expressing neurons in the MnPO can influence the activity of neighboring neurons. Future studies utilizing the use of Gq DREADDs will need to consider the potential recruitment of additional cell populations. NEW & NOTEWORTHY Rats were injected in the median preoptic nucleus (MnPO) with either an adeno-associated virus (AAV) and excitatory (Gq) designer receptor exclusively activated by designer drugs (DREADD) construct or a control AAV. In the Gq DREADD-injected rats only, clozapine-N-oxide (CNO) increased Fos staining in the MnPO and its targets and increased neuron action potential frequency. In electrophysiology experiments with slices with DREADD cells, unlabeled cells were activated and this was likely due to nitric oxide release by the DREADD cells.
AB - Designer receptors exclusively activated by designer drugs (DREADDs) modify cellular activity following administration of the exogenous ligand clozapine-N-oxide (CNO). However, some reports indicate CNO may have off-target effects. The current studies investigate the use of Gq DREADDs in CaMKIIa-expressing neurons in the median preoptic nucleus (MnPO). Male Sprague-Dawley rats (250 g) anesthetized with isoflurane were stereotaxically microinjected in the MnPO with the Gq DREADD (AAV5-CaMKIIa-HM3D-mCherry) or control virus (AAV5-CaMKIIa-mCherry). Following a 2-wk recovery, rats were used for either immunohistochemical Fos analysis or in vitro patch-clamp electrophysiology. In Gq DREADD-injected rats, CNO induced significant increases in Fos staining in the MnPO and in regions that receive direct or indirect projections from the MnPO. In electrophysiological studies, CNO depolarized and augmented firing frequency in both Gq DREADD-positive neurons (Gq DREADD) as well as unlabeled MnPO neurons in slices from Gq DREADD-injected rats (Gq DREADDx). Gq DREADDx neurons also displayed increases in spontaneous postsynaptic current (sPSC) frequency in response to CNO. Additionally, CaMKIIa-positive MnPO neurons, which also express nitric oxide synthase (NOS), were treated with N-nitro-L-arginine (L-NNA; competitive inhibitor of NOS) and hemoglobin (NO scavenger) to assess the role of NO in Gq DREADDx neuron recruitment. Both L-NNA and hemoglobin blocked CNO-induced effects in Gq DREADDx neurons without affecting Gq DREADD neurons. These findings indicate that Gq DREADD-mediated activation of CaMKIIa/ NOS expressing neurons in the MnPO can influence the activity of neighboring neurons. Future studies utilizing the use of Gq DREADDs will need to consider the potential recruitment of additional cell populations. NEW & NOTEWORTHY Rats were injected in the median preoptic nucleus (MnPO) with either an adeno-associated virus (AAV) and excitatory (Gq) designer receptor exclusively activated by designer drugs (DREADD) construct or a control AAV. In the Gq DREADD-injected rats only, clozapine-N-oxide (CNO) increased Fos staining in the MnPO and its targets and increased neuron action potential frequency. In electrophysiology experiments with slices with DREADD cells, unlabeled cells were activated and this was likely due to nitric oxide release by the DREADD cells.
KW - DREADDs
KW - MnPO
KW - NOS1
KW - Nitric oxide
UR - http://www.scopus.com/inward/record.url?scp=85089616922&partnerID=8YFLogxK
U2 - 10.1152/JN.00239.2020
DO - 10.1152/JN.00239.2020
M3 - Article
C2 - 32697679
AN - SCOPUS:85089616922
SN - 0022-3077
VL - 124
SP - 591
EP - 609
JO - Journal of neurophysiology
JF - Journal of neurophysiology
IS - 2
ER -