VU6010608, a Novel mGlu7 NAM from a Series of N-(2-(1H-1,2,4-Triazol-1-yl)-5-(trifluoromethoxy)phenyl)benzamides

Article abstract of DOI:10.1021/acsmedchemlett.7b00429

Herein, we report the structure-activity relationships within a series of mGlu₇ NAMs based on an N-(2-(1H-1,2,4-triazol-1-yl)-5-(trifluoromethoxy)phenyl)benzamide core with excellent CNS penetration (K_p 1.9-5.8 and K_p,uu 0.4-1.4). Analogues in this series displayed steep SAR. Of these, VU6010608 (11a) emerged with robust efficacy in blocking high frequency stimulated long-term potentiation in electrophysiology studies.

Full text of DOI:10.1021/acsmedchemlett.7b00429

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Letter
VU6010608, a Novel mGlu7 NAM from a Series of N-(2-
(1H-1,2,4-triazol-1-yl)-5-(trifluoromethoxy)phenyl)benzamides
Carson W Reed, Kevin Martin McGowan, Paul Spearing, Branden J Stansley, Hanna F Roenfanz,
Darren W. Engers, Alice L Rodriguez, Eileen M Engelberg, Vincent B Luscombe, Matthew T Loch,
Jerri M. Rook, Annie L Blobaum, P. Jeffrey Conn, Colleen M Niswender, and Craig W Lindsley
ACS Med. Chem. Lett., Just Accepted Manuscript • DOI: 10.1021/acsmedchemlett.7b00429 • Publication Date (Web): 08 Nov 2017
Downloaded from http://pubs.acs.org on November 9, 2017
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VU6010608, a Novel mGlu7 NAM from a Series of N-(2-(1H-1,2,4-
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Carson W. Reed§,Ϩ Kevin M. McGowan,║,Ϩ Paul K. Spearing,║ Branden J. Stansley,║ Hanna F. Roenfanz,§ Darren
W. Engers,║ Alice L. Rodriguez,║ Eileen M. Engelberg,║ Vincent B. Luscombe,║ Matthew T. Loch,║ Daniel H.
Remke,║ Jerri M. Rook,║ Anna L. Blobaum,║ P. Jeffrey Conn,║,ϒ Colleen M. Niswender,*║,ϒ Craig W. Lindsley*║,§
║Vanderbilt Center for Neuroscience Drug Discovery, Department of Pharmacology, Vanderbilt University, Nashville, TN 37232,
United States
§Department of Biochemistry and Chemistry, Vanderbilt University, Nashville, TN 37232, USA
ϒVanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
ϨThese authors contributed equally
*Coꢀcorresponding authors
KEYWORDS: Negative allosteric modulator (NAM), metabotropic glutamate receptor 7 (mGlu7), Long term potentiation (LTP),
VU6010608
ABSTRACT: Herein, we report the structureꢀactivity relationships within a series of mGlu7 NAMs based on a Nꢀ(2ꢀ(1Hꢀ1,2,4ꢀ
triazolꢀ1ꢀyl)ꢀ5ꢀ(trifluoromethoxy)phenyl)benzamide core with excellent CNS penetration (Kps 1.9 to 5.8 and Kp,uus 0.4 to 1.4).
Analogs in this series displayed steep SAR. Of these, VU6010608 (11a) emerged with robust efficacy in blocking high frequency
stimulated longꢀterm potentiation (LTP) in electrophysiology studies.
Of the eight subtypes of metabotropic glutamate receptors
(mGlu1ꢀ8), the physiology and therapeutic potential of mGlu7 is
one of the least developed due to the absence of selective tool
compounds.1,2 Despite this deficit, mouse and human genetics
have associated mGlu7 with anxiety, depression, epilepsy,
schizophrenia, ADHD and autism.3ꢀ11 Recent efforts from our
labs, using nonꢀselective Group III mGlu receptor positive
allosteric modulators (PAMs) in combination with an mGlu7
negative allosteric modulator (NAM), synaptic localization,
and/or mGlu7 knockꢀout mice to isolate effects of selective
mGlu7 activation, have identified a role for mGlu7 in a mouse
model of Rett syndrome and cognition.12,13 Recent efforts to
develop a firstꢀinꢀclass mGlu7 PAM to further validate the Rett
connection resulted in an mGlu7ꢀpreferring PAM 1,
VU6005649, that demonstrated proꢀcognitive effects on assoꢀ
ciative learning in wild type mice.14 There have been several
mGlu7 NAM tools reported in the literature (Figure 1),15ꢀ17 and
the therapeutic potential of mGlu7 has been reviewed.18 In
2007, Tsukuba researchers reported on the first mGlu7 NAMs
2 (MDIP) and 3 (MMPIP);15 however, subsequent work with 2
and 3 demonstrated contextꢀdependent pharmacology in cells,
and a lack of activity in electrophysiological studies.17,19 Six
years later, Addex Therapeutics reported on the discovery of a
structurally related chemotype, 4 (ADX71743), with anxiolytꢀ
ic activity in several rodent models.17 However, 4 possesses
an electrophilic ketone moiety and has weak activity (in our
cell lines) at mGlu2.20 Here, we describe the identification of a
novel mGlu7 NAM chemotype, devoid of electrophilic characꢀ
ter, with potency comparable to 4 and high mGlu selectivity.
Moreover,
Figure 1. Structures of the recently reported mGlu7ꢀpreferring PAM (1)
and mGlu7 NAMs (2ꢀ4), with a conserved 5,6ꢀbicyclic chemotype.
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o
100 C, mw, 20 min, 47ꢀ82%; azaheterocycle, N,Nꢀdimethylcyclohexaneꢀ
this new series was brain penetrant and efficacious in electroꢀ
physiology studies.
1,2ꢀdiamine, K3PO4, CuI, DMF, 100 oC, 16h, 51ꢀ68%.
1
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3
4
5
6
7
8
9
As reported recently, we initiated a highꢀthroughput screenꢀ
ing (HTS) campaign on a 63,000 membered library, utilizing a
tripleꢀaddition protocol, to simultaneously identify mGlu7 agꢀ
onists, PAMs, and NAMs.14 This screen was very successful
in identifying mGlu7 PAM leads, which ultimately led to the
development of 1. This campaign also identified 156 mGlu7
antagonists/NAMs; 75 of these compounds were validated
after counterꢀscreening against untransfected HEK cells and
full concentration response curve (CRC) confirmation. Attracꢀ
tive chemotypes were evaluated against mGlu4 and mGlu8, and
selective hits were then optimized via iterative parallel syntheꢀ
sis. Of these, HTS hit 5 (Figure 2), based on an Nꢀ(2ꢀ(1Hꢀ
1,2,4ꢀtriazolꢀ1ꢀyl)phenyl)benzamide core, proved to be strucꢀ
turally distinct from the known mGlu7 NAM chemotypes (2ꢀ
4),15ꢀ17 and was prioritized for optimization. Hit 5 was selecꢀ
tive for mGlu7 (mGlu7 IC50 = 5.8 ꢀM, pIC50 = 5.24±0.05, 19±3
LꢀAP4 Min (reduced an EC80 level of activation to an EC19)
and >30 ꢀM versus mGlu4 and mGlu8), but, interestingly, apꢀ
peared to be a partial antagonist as it did not completely block
the agonist response. ADX71743 is more potent (mGlu7 IC50
= 676 nM,
pIC50 = 6.17±0.06, 8±1 LꢀAP4 Min) than 5, but also a partial
antagonist in our in vitro assay.17,20 From an optimization
standpoint, 5 was attractive in that multiple regions could be
evaluated in parallel.
The resynthesis of 5, and the rapid synthesis of novel anaꢀ
logs 11, was straightforward, requiring only four steps from
commercial materials (Scheme 1).20 Methyl 4ꢀhydroxyꢀ3ꢀ
methoxybenzoate 6 was alkylated under standard conditions to
afford analogs 7 (diverse R1), followed by ester hydrolysis to
deliver benzoic acids 8. A variety of 5ꢀsubstituted (R2), 2ꢀ
bromoanilines 9 were coupled to acids 8 under PyClU condiꢀ
tions to give amides 10. Finally, a copperꢀmediated Ullman
coupling provided analogs 11. Overall, yields were good, and
a broad range of diversity was tolerated. In addition, 10 also
was a competent partner for Suzuki and Stille couplings, under
standard conditions, where aryl and heteroaryl congeners were
also surveyed.
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Figure 3. Substituents explored in analogs 11 that were inactive as mGlu7
NAMs (IC50s > 10 ꢀM).
Evaluation of analogs 11 in our functional mGlu7 assay12ꢀ
14,20
demonstrated steep SAR (akin to the SAR noted with the
Figure 2. Structure of HTS hit 5 (VU6009748), and the multiple regions
to be surveyed in the lead optimization campaign.
mGlu7 PAM 1), and compound 5 is included for comparison
(R2 = Cl).14 Here, the majority of ~100 analogs prepared were
inactive (IC50s >10 ꢀM) at mGlu7 (Figure 3). The 1,2,4ꢀ
triazole proved essential for mGlu7 NAM activity, with other
regioisomeric triazoles, pyrazoles, pyroles and imidazoles
devoid of activity. Ring expansions to 6ꢀmembered azaheteroꢀ
cycles, accessed via Suzuki couplings, were also inactive.
Similarly, the 5ꢀposition (R2) was largely intolerant of change,
with only an OCF3 moiety proving superior to chlorine. While
alternate ethers in the 4ꢀposition (R1) were active, increasing
steric bulk
Scheme 1. Synthesis of Analogues 11a
Table 1. Structures and Activities of Compound 5 and Analogs 11a
OCF3
O
OMe
N
aReagents and conditions: (a) R1X, K2CO3, DMF, 100 oC, 3h, 94ꢀ97%; (b)
LiOH, THF:H2O (1:1), 60 oC, 2 h, quantitative; (c) PyClU, DIEA, CH2Cl2,
H
N
R1
O
N
N
11
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R1
rmGlu7 IC50
(ꢀM)a
rmGlu7
pIC50
Rat Kp
Rat fubrain
0.034
0.017 0.009 0.013 0.013
Compound
b
(Kp,uu
)
1
2
3
4
5
6
7
8
(±SEM)
[% LꢀAP4
Min ±SEM]
As in vitro potency and CNS penetration were generally
conserved and favorable for 11aꢀe, in vitro DMPK profiles
(Table 2) were employed to prioritize advanced characterizaꢀ
tion towards a tool compound. In terms of cLogP (2.86), moꢀ
lecular weight (408), fraction unbound in both mouse (fu =
0.178) and rat (fu = 0.244) plasma and rat brain (fu = 0.038),
11a (VU6010608) was superior amongst the new analogs 11.
In addition, 11a displayed low predicted hepatic clearance in
Me
Me
Et
5
5.8
[19+3]
5.24+0.05
6.12+0.04
6.29+0.08
ND
3.4
11a
11b
11c
0.76
[15+3]
(0.48)
9
0.51
[11+2]
3.5
(0.83)
10
11
12
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19
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21
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23
nPr
rat (CLhep = 9.5 mL/min/kg) and moderate in mouse (CLhep
=
0.78
[19+5]
1.9
(1.0)
6.11+0.05
48.5 mL/min/kg). 11e, the cyclopropyl congener, was the
closest competitor, with low predicted hepatic clearance in rat
(CLhep = 1.6 mL/min/kg), but a higher cLogP and lower absoꢀ
lute plasma and brain levels in the rat PBL cassette study (data
not shown) diverted all attention to 11a.21
iPr
11d
11e
11f
0.78
[14+4]
6.11+0.07
6.15+0.11
4.4
(0.89)
0.71
[11+3]
5.8
(1.5)
In vivo, 11a displayed a poor in vitro:in vivo correlation
(IVIVC), displaying high clearance in rat (CLp = 64.2
mL/min/kg), with a 1.73 hour halfꢀlife and high volume (Vss =
6.2 L/kg), yet with acceptable oral bioavailability (18.9 %F).
From previous experience, we assumed that CYPꢀmediated
oxidative dealkylation of one or both methoxy moieties in 11a
might also be a contributor to the high in vivo clearance.
Thus, we prepared both the 3ꢀ and 4ꢀOCD3 congeners as well
as the 3,4ꢀdiꢀOCD3 analog, and found that these modifications
had no impact on clearance. A metabolite identification study
in rat hepatic S9 proved informative, as the major metabolite
was determined to be amide hydrolysis.20 Future efforts within
this series would have to focus on the modification of the amꢀ
ide linker.
1.4
[10+3]
ND
5.87+0.07
aCalcium mobilization assays with rat mGlu7/Gα15/HEK cells performed in the
presence of an EC80 fixed concentration of LꢀAP4; values represent
means from three (n=3) independent experiments performed in triplicate.b Total and
calculated unbound brain:plasma partition coefficients determined at 0.25 h postꢀ
administration of an IV cassette dose (0.20–0.25 mg/kg) to male, SD rats (n = 1), in
conjunction with in vitro rat plasma protein and brain homogenate binding assay data.
ND = not determined.
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led to a diminution in potency (e.g., 11f, mGlu7 IC50 = 1.4
ꢀM). Importantly, the 3ꢀmethoxy moiety was also essential
and intolerant to any modifications. Reverse amides, sulfonꢀ
amides and αꢀtrifluromethyl amines were not effective as linkꢀ
er replacements, and additional substituents to the ether aryl
ring (even fluorine) led to a complete loss of mGlu7 NAM
activity, as did the incorporation of heterocyclic systems.
However, the analogs 11a-f with mGlu7 NAM activity (Table
1) generally displayed favorable brain penetration (Kps > 1,
Kp,uus >0.4) in our high throughput rat plasma:brain level
(PBL) cassette paradigm,21 and all proved to be partial antagoꢀ
nists (mGlu7 Glu Min 10ꢀ19%).21 The steep (all active analogs
possessed IC50s in the ~700 nM range) and flat (minor strucꢀ
tural changes led to loss of mGlu7 NAM activity) SAR profile
of analogs 11 left five analogs (11aꢀe) for DMPK profiling to
assess potential as in vivo tools.14,20,21
As many of our rodent behavioral models related to mGlu7
are performed in mice,12ꢀ14,22 we evaluated the CNS penetraꢀ
tion of 11a in an intraperitoneal (IP) mouse PBL study. At a
standard dose of 10 mg/kg IP, a Kp of 2.01 was observed, with
a Kp,uu of 0.44, comparable to the rat data. However, both total
brain (380 nM) and free brain levels (14.3 nM) were below the
in vitro mGlu7 IC50. Thus, we performed a mouse IP PBL
dose response at 100 mg/kg to assess if 11a achieved suffiꢀ
cient exposure to serve as an in vivo tool compound (Table 3).
At 100 mg/kg, total brain levels (1.55 ꢀM) were twoꢀfold
above the in vitro mGlu7 IC50, but free brain levels peaked at
only 59 nM. Thus, if efficacy was driven by total brain, 11a is
a reasonable in vivo tool, but not if efficacy requires free brain
concentrations at or above the in vitro IC50. We would note
that, when dosed at 100 mg/kg, neither 11a nor 4 showed any
adverse effects in a standard CNS mouse study.23
Table 2. In vitro DMPK Profiles of Analogs 11.
Property
MW
11a
408
2.86
84.7
11b
422
3.41
84.5
11c
11d
436
4.32
84.5
11e
436
4.41
84.5
434
3.96
84.5
cLogP
TPSA
Table 3. Mouse IP PBL exposure for 11a.
Dose
Plasma
Plasma
(free,
nM)
Brain
Brain
Kp
Kp,uu
0.44
In vitro PK parameters
CLHEP (mL/min/kg), rat
(mg/kg)
(total,
nM)
(total,
nM)
(free,
nM)
9.50
26.2
68.4
36.9
72.9
31.4
65.1
1.66
46.6
CLHEP (mL/min/kg), mouse 48.3
Rat fuplasma
Mouse fuplasma
0.244
0.178
0.072 0.017 0.065 0.052
0.086 0.019 0.063 0.039
10
180
32.5
380
14.3
2.01
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402
772
71.5
137
952
36.2
59.0
2.36
2.00
0.51
0.43
towards the goal of developing a robust in vivo mGlu7 NAM
probe, as well as the optimization of other mGlu7 NAM hits
from our HTS campaign, which will be reported in due course.
1
2
100
1,550
3
4
5
6
7
8
9
Thus, while 11a would not be suitable as an in vivo tool
for robust target validation studies, we were still excited about
its potential as an in vitro tool and for electrophysiology studꢀ
ies. First, however, we needed to assess mGlu receptor selecꢀ
tivity and broader ancillary pharmacology for 11a prior to any
further studies. Fortunately, 11a was inactive (EC50/IC50s > 10
ꢀM) against mGlu1,2,3,4,5,6,8, and was a highly selective mGlu7
NAM (as opposed to 4, which in our inꢀhouse mGlu selectiviꢀ
ty panel, shows weak mGlu2 activity).19 Furthermore, in a
broader ancillary pharmacology (a Eurofins Lead profiling
panel of 68 GPCRs, ion channels and transporters), no signifiꢀ
cant activities were noted at 10 ꢀM.20
AUTHOR INFORMATION
Corresponding Authors
*(CMN). Phone: 1 615ꢀ343ꢀ4303. Fax: 1 615ꢀ936ꢀ4381. Email:
colleen.niswender @vanderbilt.edu.
*(CWL). Phone: 1 615ꢀ322ꢀ8700. Fax: 1 615ꢀ936ꢀ4381. Email:
craig.lindsley@vanderbilt.edu.
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Author Contributions
CWL, CMN, PJC, JMR, and BJS drafted/corrected the manuscript.
CWR, KMM, PKS, HFR and DWE performed the chemical synthesis.
CWL, PJC, CMN, JKR, and ALR oversaw the target selection and
interpreted the biological data. EE, VBL, MTL, and ALR performed
the in vitro molecular pharmacology studies and the HTS. ALB perꢀ
formed the in vitro and in vivo DMPK studies. JMR oversaw the in
vivo experiments. DHR performed the in vivo studies. BJS performed
the electrophysiology studies. All authors have given approval to the
final version of the manuscript.
mGlu7 is broadly distributed within the mammalian CNS
where it plays a key role in neuronal function and synaptic
plasticity.1,2 We have previously shown that mGlu7 regulates
longꢀterm potentiation (LTP), and that antagonism of mGlu7
using ADX71743 completely blocks LTP at Schaffer Collatꢀ
eral (SC) SCꢀCA1 synapses in brain slices in wildꢀtype mice.12
Thus, we were pleased to see that the mGlu7 NAM 11a could
block LTP at SCꢀCA1 in brain slices induced by high frequenꢀ
cy stimulation (Figure 4), further highlighting the utility of
11a as an in vitro probe.20
Acknowledgement
The authors would also like to thank William K. Warren, Jr.
and the William K. Warren Foundation who funded the
William K. Warren, Jr. Chair in Medicine (to C.W.L.). Studies
were also supported by PR160102 (CDRMP to C.M.N.). We
would like to thank the Vanderbilt High Throughput Screening
Facility for their assistance with primary screening.
ASSOCIATED CONTENT
Supporting Information. General methods for the synthesis and
characterization of all compounds, and methods for the in vitro
and in vivo DMPK protocols and supplemental figures. This maꢀ
terial is available free of charge via the Internet at
http://pubs.acs.org.
ABBREVIATIONS
LTP, longꢀterm potentiation; HFS, high frequency stimulation; metaboꢀ
tropic glutamate receptor (mGlu); PAM, positive allosteric modulator;
NAM, negative allosteric modulator; HTS, highꢀthroughput screen; PBL,
plasma:brain level;
Figure 4. HFSꢀinduced LTP is blocked by the mGlu7 NAM VU6010608
(11a). (A) Time course showing the effects of vehicle or mGlu7 NAM
(VU6010608, 10 µM, grey symbols) followed by highꢀfrequency stimulaꢀ
tion (HFS; 2 x 100 Hz, 20 sec ISI) on fEPSP slope. (B) Comparison beꢀ
tween drug treatment groups based on average slope from last 5 minutes
of recording. (**p<0.01 compared to Vehicle; Student’s tꢀtest, n=4 per
group). Data are expressed as mean ± SEM.
REFERENCES
1. Niswender, C.M. and Conn, P.J. Metabotropic glutamate recepꢀ
tors:physiology,pharmacology,and disease. Annu.Rev.Pharmacol. Toxicol
2010, 50, 295−322.
11a, a highly selective mGlu7 NAM based on a novel
chemotype (and devoid of reactive functionality), provides the
field with a much needed in vitro tool compound to further
dissect the physiology and therapeutic potential of mGlu7.
While this series, and 11a in particular, possesses good free
fraction and CNS penetration, total and free brain levels limit
its translational utility as an in vivo probe. However, 11a afꢀ
forded robust efficacy in blocking high frequency stimulated
LTP, and has broad utility in other in vitro molecular pharmaꢀ
cology studies. Additional optimization of 11a is underway
2. Lindsley, C.W.; Emmitte, K.A.; Hopkins, C.R.; Bridges, T.M.;
Gregory, K.A.; Niswender, C.M.; Conn, P.J. Practical strategies and conꢀ
cepts in GPCR allosteric modulator discovery: Recent advances with
metabotropic glutamate receptors’ Chem. Rev. 2016, 116, 6707ꢀ6741.
3. Sansig, G.; Bushell, T. J.; Clarke, V. R.; Rozov, A.; Burnashev, N.;
Portet, C.; Gasparini, F.; Schmutz, M.; Klebs, K.; Shigemoto, R.; Flor, P.
J.; Kuhn, R.; Knoepfel,T.; Schroeder, M.; Hampson, D. R.; Collett,V. J.;
Zhang, C.; Duvoisin, R. M.; Collingridge, G. L.; van Der Putten, H. Inꢀ
creased seizure susceptibility in mice lacking metabotropic glutamate
receptor 7. J. Neurosci. 2001, 21, 8734−8745.
4
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4. Goddyn, H.; CallaertsꢀVegh, Z.; Stroobants, S.; Dirikx, T.;
Poli, S.; Neale, S.A.; Salt, T.E.; Lutjens, R. ADX71743, a potent and
selective negative allosteric modulator of metabotropic glutamare receptor
7: in vitro and in vivo characterization. J. Pharmacol. Exp. Ther. 2013, 3,
624ꢀ636.
Vansteenwegen, D.; Hermans, D.; van der Putten, H.; D'Hooge, R.
Deficits in acquisition and extinction of conditioned responses in mGluR7
knockout mice. Neurobiol Learn Mem 2008, 90, 103ꢀ111.
1
2
3
4
5
6
7
8
9
5. Palucha, A.; Klak, K.; Branski, P.; van der Putten, H.; Flor, P.J.;
Pilc, A. Activation of the mGlu7 receptor elicits antidepressantꢀlike efꢀ
fects in mice. Psychopharmacology 2007, 194, 555ꢀ562.
6. CallaertsꢀVegh, Z.; Beckers, T.; Ball, S.M.; Baeyens, F.; Callaerts,
P.F.; Cryan, J.F.; Molnar, E.; D'Hooge, R. Concomitant deficits in
working memory and fear extinction are functionally dissociated from
reduced anxiety in metabotropic glutamate receptor 7ꢀdeficient mice. J
Neurosci 2006, 26, 6573ꢀ6582.
7. Mitsukawa, K.; Mombereau, C.; Lotscher, E.; Uzunov, D.P.; van der
Putten, H.; Flor, P.J.; Cryan, J.F. Metabotropic Glutamate Receptor Subꢀ
type 7 Ablation Causes Dysregulation of the HPA Axis and Increases
Hippocampal BDNF Protein Levels: Implications for StressꢀRelated Psyꢀ
chiatric Disorders. Neuropsychopharmacology 2006, 31, 1112ꢀ1122.
8. Holscher, C.; Schmid, S.; Pilz, P.K.; Sansig, G.; van der Putten, H.;
Plappert, C.F. Lack of the metabotropic glutamate receptor subtype 7
selectively modulates Theta rhythm and working memory. Learn Mem
2005, 12, 450ꢀ455.
9. Holscher, C.; Schmid, S.; Pilz, P.K.; Sansig, G.; van der Putten, H.;
Plappert, C.F. Lack of the metabotropic glutamate receptor subtype 7
selectively impairs shortꢀterm working memory but not longꢀterm
memory. Behav. Brain Res. 2004, 154, 473ꢀ481.
10. Bushell, T.J.; Sansig, G.; Collett, V.J.; van der Putten, H.;
Collingridge, G.L. Altered shortꢀterm synaptic plasticity in mice lacking
the metabotropic glutamate receptor mGlu7. ScientificWorldJournal 2002,
2, 730ꢀ737.
11. Masugi, M.; Yokoi, M.; Shigemoto, R.; Muguruma, K.; Watanabe,
Y.; Sansig, G.; van der Putten, H.; Nakanishi, S. Metabotropic glutamate
receptor subtype 7 ablation causes deficit in fear response and conditioned
taste aversion. J. Neurosci. 1999, 19, 955ꢀ963.
12. Gogliotti R.G., Senter R.K. , Fisher N.M , Adams J. , Zamorano R. ,
Walker A.G., Blobaum A.L. , Engers D.W. , Hopkins C.R. , Daniels J.S.,
Jones, C.K. , Lindsley C.W., Xiang Z., Conn P.J., and Niswender C.M.
Metabotropic Glutamate Receptor 7 Allosteric Modulation Rescues Long
Term Potentiation, Cognition and Apneas in Mecp2ꢀDeficient Mice. Sci.
Trans. Med. 2017, 9, aai7459.
13. JalanꢀSakrikar, N.; Field, J.R.; Klar, R.; Mattmann, M.E.; Gregory,
K.J.; Zamorano, R.; Engers, D.W.; Bollinger, S.R.; Weaver, C.D.; Days,
E.; Lewis, L.M.; Utley, T.J.; Hurtado, M.; Rigault, D.; Acher, F.; Walker,
A.G.; Melancon, B.J.; Wood, M.R.; Lindsley, C.W.; Conn, P.J.; Xiang, Z.;
Hopkins, C.R.; Niswender, C.M. Identification of positive allosteric modꢀ
ulators VU0155094 (ML397) and VU0422288 (ML396) reveals new
insights into the biology of metabotropic glutamate receptor 7. ACS Chem.
Neurosci. 2014, 5, 1221ꢀ1237.
18. Palazzo, E.; Marabese, I.; de Novellis, V.; Rossi, F.; Maione, S.
Metabotropic glutamate receptor 7: From synaptic function to therapeutic
implications. Curr. Neuropharmacol. 2016, 14, 504ꢀ513.
19. Niswender, C.M.; Johnson, K.A.; Miller, N.R.; Ayala, J.E.; Luo, Q.;
Williams, R.; Saleh, S.; Orton, D.; Weaver, C.D.; Conn, P.J. Contextꢀ
dependent pharmacology exhibited by negative allosteric modulators of
metabotropic glutamate receptor 7. Mol. Pharmacol. 2010, 77, 459–468.
20. See Supporting Information for full experimental details.
21. Bubser, M.; Bridges, T.M.; Denker, D.; Gould, R.W.; Grannan, M.;
Noetzel, M.J.; Lamsal, A.; Niswender, C.M.; Daniels, J.S.; Poslusney,
M.S.; Melancon, B.J.; Tarr, J.C.; Byers, F.W.; Wess, J.; Duggan, M.E.;
Dunlop, J.; Wood, M.W.; Brandon, N.J.; Wood, M.R.; Lindsley, C.W.;
Conn, P.J.; Jones C.K. Selective activation of M4 muscarinic acetylcholine
receptors reverses MKꢀ801ꢀinduced behavioral impairments and enhances
associative learning in rodents. ACS Chem. Neurosci. 2014, 5, 920ꢀ942.
22. Rodriguez, A.L.; Nong, Y.; Sekeran, N.; Alagille, D.; Tamagnan,
G.D.; Conn, P.J. A close structural analog of 2ꢀMethylꢀ6ꢀ(phenylethynyl)ꢀ
pyridine acts as a neutral allosteric site ligand on metabotropic glutamate
receptor subtype 5 and blocks the effects of multiple allosteric modulators.
Mol. Pharmacol. 2005, 68, 1793ꢀ1802.
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11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
23. Rook, J.M.; Abe, M.; Cho, H.P.; Nance, K.D.; Luscombe, V.B.;
Adams, J.J.; Dickerson, J.W.; Remke, D.H.; GarciaꢀBarrantes, P.M.;
Engers, D.W.; Engers, J.L.; Chang, S.; Foster, J.J.; Blobaum, A.L.;
Niswender, C.M.; Jones, C.K.; Conn, P.J.; Lindsley, C.W. Diverse effects
on M1 signaling and adverse effect liability within a series of M1 agoꢀ
PAMs. ACS Chem, Neurosci. 2017, 8, 866ꢀ883.
14. Abe, M.; Seto, M.; Gogliotti, R.G.; Loch, M.T.; Bollinger, K.A.;
Chang, S.; Engelberg, E.M.; Luscombe, V.B.; Harp, J.M.; Bubser, M.;
Engers, D.W.; Jones, C.K.; Rodriguez, A.L.; Blobaum, A.L.; Conn, P.J.;
Niswender, C.M.; Lindsley, C.W. Discovery of VU6005649, a CNS peneꢀ
trant mGlu7/8 receptor PAM from a series of pyrazolo[1,5ꢀa]pyrimidines.
ACS Med. Chem. Lett. 2017, 8, 1110ꢀ1115.
15. Suzuki, G; Tsukamoto, N; Fushiki, H.; Kawagishi, A.; Nakamura,
M.; Kurihara, H.; Mitsuya, M.; Ohkubo, M.; Ohta, H. In vitro pharmacoꢀ
logical characterization of novel isoxazolopyridone derivatives as allosterꢀ
ic metabotropic glutamate receptor 7 antagonists. J. Pharmacol. Exp.
Ther. 2007, 323, 147–156.
16. Nakamura, M.; Kurihara, H.; Suzuki, G.; Mitsuya, M.; Ohkubo, M.;
Ohta, H. Isoxazolopyridone derivatives as allosteric metabotropic glutaꢀ
mate receptor 7 antagonists. Bioorg. Med. Chem. Lett. 2010, 20, 726–729.
17. Kalinichev, M.; Rouillier, M.; Girard, F.; RoyerꢀUrios, I.;
Bournique, B.; Finn, T.; Charvin, D.; Campo, B.; Le Poul, E.; Mutel, V.;
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VU6010608, a Novel mGlu7 NAM from a Series of N-(2-(1H-1,2,4-
trizol-1-yl)-5-(trifluoromethoxy)phenyl)benzamides
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Carson W. Reed§, Kevin M. McGowan, Paul K. Spearing, Branden J. Stansley, Hanna F. Roenfanz,
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Darren W. Engers, Alice L. Rodriguez, Eileen Engelberg, Vincent Luscombe, Matthew T. Loch, Jerri M.
║,§
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║,ϒ
║,ϒ
Rook, Anna L. Blobaum, P. Jeffrey Conn, Colleen M. Niswender,* Craig W. Lindsley*
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