hmGluR2 (EC50 = 2.69 nM); hmGluR3 (EC50 = 4.48 nM); hmGluR2 (Ki = 14.1 nM); hmGluR3 (Ki = 5.8 nM)

After subjecting astrocytes to LY379268 (0.1 μM; 24-48 hours) for nine weeks (9w), there was a decrease in mitochondrial ROS levels and apoptosis and an increase in mGlu3R and Nrf2 protein levels and SOD activity. In co-culture studies, mGlu3R activation in aging astrocytes also inhibited Aβ1-42-induced hippocampus neuronal loss. Antioxidant effects and protection of hippocampal neurons from Aβ-induced neurotoxicity are shown when mGlu3R is activated in aged astrocytes [3].

In the case of LY379268, the start of inflammatory hyperalgesia was greatly delayed without impacting paw inflammation when a dose of 3 mg/kg was administered prior to plantar injection of carrageenan [2]. Before subcutaneously injecting capsaicin into the tail of a mouse used in a tail-retraction experiment with warm water, LY379268 (12 mg/kg; i.p.) was administered to minimize the ensuing neurogenic hyperalgesia [2].

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1. Previous studies investigating the role of metabotropic glutamate (mGlu) receptors in nociceptive processing have been hampered by the lack of systemically active, selective, ligands. This study investigates the possible analgesic and/or anti-hyperalgesic properties of the most potent compound to date that has systemic agonist activity at group II mGlu receptors, LY379268. 2. In testing the drug in rats as an analgesic to acute noxious stimuli, LY379268 (in doses up to 3 mg kg(-1) i.p.) did not affect withdrawal latencies to either mechanical or thermal stimulation. 3. However, when a 3 mg kg(-1) dose was given prior to an intraplantar injection of carrageenan, the inflammatory hyperalgesia that developed was significantly delayed compared to saline pre-treated controls, without affecting the inflammation of the paw. A similar dose of the mGlu-inactive enantiomer, LY379267, was not anti-hyperalgesic. 4. In a model of mouse tail withdrawal to warm water, LY379268 (12 mg kg(-1) i.p.), given before a subcutaneous tail injection of capsaicin, reduced the subsequent neurogenic hyperalgesia. 5. Rota-rod testing showed that the drug did not produce a motor impairment in rats at antihyperalgesic doses. 6. The results indicate that systemic activation of this group of mGlu receptors reduces both inflammatory and neurogenic thermal hyperalgesia [2].

As part of our ongoing research program aimed at the identification of highly potent, selective, and systemically active agonists for group II metabotropic glutamate (mGlu) receptors, we have prepared novel heterobicyclic amino acids (-)-2-oxa-4-aminobicyclo[3.1. 0]hexane-4,6-dicarboxylate (LY379268, (-)-9) and (-)-2-thia-4-aminobicyclo[3.1.0]hexane-4,6-dicarboxylate (LY389795, (-)-10). Compounds (-)-9 and (-)-10 are structurally related to our previously described nanomolar potency group II mGlu receptor agonist, (+)-2-aminobicyclo[3.1.0]hexane-2,6-dicarboxylate monohydrate (LY354740 monohydrate, 5), with the C4-methylene unit of 5 being replaced with either an oxygen atom (as in (-)-9) or a sulfur atom (as in (-)-10). Compounds (-)-9 and (-)-10 potently and stereospecifically displaced specific binding of the mGlu2/3 receptor antagonist ([3H]LY341495) in rat cerebral cortical homogenates, displaying IC50 values of 15 +/- 4 and 8.4 +/- 0.8 nM, respectively, while having no effect up to 100 000 nM on radioligand binding to the glutamate recognition site on NMDA, AMPA, or kainate receptors. Compounds (-)-9 and (-)-10 also potently displaced [3H]LY341495 binding from membranes expressing recombinant human group II mGlu receptor subtypes: (-)-9, Ki = 14.1 +/- 1.4 nM at mGlu2 and 5.8 +/- 0.64 nM at mGlu3; (-)-10, Ki = 40.6 +/- 3.7 nM at mGlu2 and 4.7 +/- 1.2 nM at mGlu3. Evaluation of the functional effects of (-)-9 and (-)-10 on second-messenger responses in nonneuronal cells expressing human mGlu receptor subtypes demonstrated each to be a highly potent agonist for group II mGlu receptors: (-)-9, EC50 = 2.69 +/- 0.26 nM at mGlu2 and 4.58 +/- 0.04 nM at mGlu3; (-)-10, EC50 = 3.91 +/- 0.81 nM at mGlu2 and 7.63 +/- 2. 08 nM at mGlu3. In contrast, neither compound (up to 10 000 nM) displayed either agonist or antagonist activity in cells expressing recombinant human mGlu1a, mGlu5a, mGlu4a, or mGlu7a receptors. The agonist effects of (-)-9 and (-)-10 at group II mGlu receptors were not totally specific, however, as mGlu6 agonist activity was observed at high nanomolar concentrations for (-)-9 (EC50 = 401 +/- 46 nM) and at micromolar concentrations (EC50 = 2 430 +/- 600 nM) for (-)-10; furthermore, each activated mGlu8 receptors at micromolar concentrations (EC50 = 1 690 +/- 130 and 7 340 +/- 2 720 nM, respectively). Intraperitoneal administration of either (-)-9 or (-)-10 in the mouse resulted in a dose-related blockade of limbic seizure activity produced by the nonselective group I/group II mGluR agonist (1S,3R)-ACPD ((-)-9 ED50 = 19 mg/kg, (-)-10 ED50 = 14 mg/kg), indicating that these molecules effectively cross the blood-brain barrier following systemic administration and suppress group I mGluR-mediated limbic excitation [1].

Astrocytes play a key role by providing antioxidant support to nearby neurons under oxidative stress. We have previously demonstrated that in vitro astroglial subtype 3 metabotropic glutamate receptor (mGlu3R) is neuroprotective. However, its role during aging has been poorly explored. Our study aimed to determine whether LY379268, an mGlu3R agonist, exerts an antioxidant effect on aged cultured rat astrocytes. Aged cultured astrocytes obtained after 9-weeks (9w) in vitro were positive for β-galactosidase stain, showed decreased mGlu3R and glutathione (GSH) levels and superoxide dismutase (SOD) activity, while nuclear erythroid factor 2 (Nrf2) protein levels, reactive oxygen species (ROS) production and apoptosis were increased. Treatment of 9w astrocytes with LY379268 resulted in an increase in mGlu3R and Nrf2 protein levels and SOD activity, and decreased mitochondrial ROS levels and apoptosis. mGlu3R activation in aged astrocytes also prevented hippocampal neuronal death induced by Aβ1-42 in co-culture assays. We conclude that activation of mGlu3R in aged astrocytes had an anti-oxidant effect and protected hippocampal neurons against Aβ-induced neurotoxicity. The present study suggests mGlu3R activation in aging astrocytes as a therapeutic strategy to slow down age-associated neurodegeneration [3].

LY379268 and its mGlu receptor-inactive enantiomer, LY379267 were dissolved in equimolar NaOH and adjusted to a pH of 7 – 9 with equimolar HCl. [2]

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Experimental design [2]
The experimenter was ‘blind' to the treatment under test. In all tests, ‘control' readings were taken immediately before i.p. injection of either vehicle (saline) or test agent (LY379268 or LY379267) in a volume of 2 ml kg−1, and before the induction of hyperalgesia.

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Protocol 1 [2]
The analgesic effects of LY379268 or LY379267 were tested on responses to thermal and mechanical stimuli (PWL and PWT) in rats without hind paw inflammation.

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Protocol 2 [2]
The analgesic effects of LY379268 were tested in mice on TWL to hot water at 50°C. To match protocol 6 below, tests were repeated four times at 3 min intervals 1 h after drug administration.

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Protocol 3 [2]
The ability of LY379268 to reverse inflammatory hyperalgesia was tested by i.p. injection 3 h after carrageenan injection. Thermal PWL was tested hourly for a further 3 h.

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Protocol 4 [2]
The ability of LY379268 to prevent the induction of inflammatory hyperalgesia was assessed by administering drug concurrently with carrageenan, after having made baseline readings of PWL. Measurements of thermal PWL were made hourly for the following 4 h.

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Protocol 5 [2]
As Protocol 4 but drug was administered 1 h before carrageenan was injected into one hind paw. PWLs were then tested hourly for a further 4 h.

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Protocol 6 [2]
LY379268 or vehicle was given 1 h prior to an injection of capsaicin into the tail of mice. The degree of neurogenic thermal hyperalgesia was tested by TWL to warm water at 47°C. This lower water temperature than for Protocol 2 gave baseline latencies close to cut off so as to maximize the ability to detect hyperalgesia. TWL tests were repeated before and 3, 6 and 9 min after capsaicin.

[1]. Synthesis, pharmacological characterization, and molecular modeling of heterobicyclic amino acids related to (+)-2-aminobicyclo[3.1.0] hexane-2,6-dicarboxylic acid (LY354740): identification of two new potent, selective, and systemically active agonists for group II metabotropic glutamate receptors. J Med Chem. 1999 Mar 25;42(6):1027-40.

[2]. Systemic pre-treatment with a group II mGlu agonist, LY379268, reduces hyperalgesia in vivo. Br J Pharmacol. 2002 Mar;135(5):1255-62.

[3]. Antioxidant and neuroprotective effects of mGlu3 receptor activation on astrocytes aged in vitro. Neurochem Int. 2020 Nov;140:104837.

LY 379268 is an organic heterobicyclic compound that is (1R,5S)-2-oxabicyclo[3.1.0]hexane carrying amino, carboxy, and carboxy groups at positions 4R, 4R and 6R, respectively. It is a potent agonist of group II metabotropic glutamate receptors mGluR2 and mGluR3 (EC50 = 2.69 nM and 4.48 nM, respectively) that exhibits antipsychotic-like action in animal models of schizophrenia. It has a role as a metabotropic glutamate receptor agonist, a neuroprotective agent, an antipsychotic agent and an anxiolytic drug. It is an organic heterobicyclic compound, a bridged compound and an amino dicarboxylic acid.

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LY379268 ((−)-9) and LY389795 ((−)-10) are the most potent agonists yet described for group II metabotropic glutamate receptors. The high mGlu2/3 potency and selectivity evinced by these heterobicyclic amino acids lend further experimental evidence supporting the hypothesis that glutamate interacts with mGlu2/3 receptors in a fully extended conformation. Like 5, heterocycles (−)-9 and (−)-10 effectively penetrate into the CNS following systemic administration and block seizures induced by group I mGlu receptor activation. Thus, like 5, these agents may be useful for studying the functions of mGlu2/3 receptors both in vitro and in vivo.[1]

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In rats, the dose of LY379268 that was anti-hyperalgesic had no effect on rota-rod performance (see also Simmons et al., 1998). However, examination of LY379268 at higher doses was limited due to the induction of exaggerated startle responses. Given that other compounds in this structural series do not show the same effects (unpublished observations), this effect may reflect activity either at other glutamate receptors (perhaps mGlu8, at which LY379268 has activity in vitro; Monn et al., 1999) or at non-glutamate receptors. LY379267, the enantiomer of LY379268, has no agonist or antagonist activity at any mGlu receptor subtype (unpublished data) and in the present study had no anti-hyperalgesic effects, although it did cause an unexplained increase in carrageenan hyperalgesia without affecting baseline values; this is presumably due to an unidentified non-mGlu receptor interaction. In conclusion, this study shows that the systemic activation of group II mGlu receptors can reduce the induction phase of hyperalgesia at doses that do not have motor or other obvious side effects. This lends impetus to the further dissection of the relative roles of mGlu2 and mGlu3 receptor subtypes in the central sensitization process associated with persistent pain.[2]

C7H9NO5

187.15006

187.048

C, 44.92; H, 4.85; N, 7.48; O, 42.74

191471-52-0

10197984

White to off-white solid powder

-4.3

3

6

2

13

291

4

C1[C@]([C@@H]2[C@H]([C@@H]2O1)C(=O)O)(C(=O)O)N

YASVRZWVUGJELU-MDASVERJSA-N

InChI=1S/C7H9NO5/c8-7(6(11)12)1-13-4-2(3(4)7)5(9)10/h2-4H,1,8H2,(H,9,10)(H,11,12)/t2-,3-,4+,7+/m1/s1

(1S,2R,5R,6R)-2-amino-4-oxabicyclo[3.1.0]hexane-2,6-dicarboxylic acid

LY379268; LY 379268; 191471-52-0; (1R,4R,5S,6R)-4-Amino-2-oxabicyclo[3.1.0]hexane-4,6-dicarboxylic acid; LY-379268; 2-Oxabicyclo[3.1.0]hexane-4,6-dicarboxylic acid, 4-amino-, (1R,4R,5S,6R)-; CHEMBL275079; S96JF4J697; LY-379268.

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

0.1 M NaOH : ~200 mg/mL (~1068.66 mM)
H2O : ~2 mg/mL (~10.69 mM)

Solubility in Formulation 1: 25 mg/mL (133.58 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with sonication.

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 (Please use freshly prepared in vivo formulations for optimal results.)