1‐Aminoindan‐1,5‐dicarboxylic acid and (S)‐(+)‐2‐(3′‐carboxybicyclo[1.1.1] pentyl)‐glycine, two mGlu1 receptor‐preferring antagonists, reduce neuronal death in in vitro and in vivo models of cerebral ischaemia

Abstract

Metabotropic glutamate (mGlu) receptors have been implicated in a number of physiological and pathological responses to glutamate, but the exact role of group I mGlu receptors in causing postischaemic injury is not yet clear. In this study, we examined whether the recently-characterized and relatively selective mGlu1 receptor antagonists 1-aminoindan-1,5-dicarboxylic acid (AIDA) and (S)-(+)-2-(3'-carboxybicyclo[1.1.1]pentyl)-glycine (CBPG) could reduce neuronal death in vitro, following oxygen-glucose deprivation (OGD) in murine cortical cell and rat organotypic hippocampal cultures, and in vivo, after global ischaemia in gerbils. When present in the incubation medium during the OGD insult and the subsequent 24 h recovery period, AIDA and CBPG significantly reduced neuronal death in vitro. The extent of protection was similar to that observed with the nonselective mGlu receptor antagonist (+)-alpha-methyl-4-carboxyphenylglycine [(+)MCPG] and with typical ionotropic glutamate (iGlu) receptor antagonists. Neuroprotection was also observed when AIDA or CBPG were added only after the OGD insult was terminated. Neuronal injury was not attenuated by the inactive isomer (-)MCPG, but was significantly enhanced by the nonselective mGlu receptor agonist (1S,3R)-1-aminocyclopentane-1, 3-dicarboxylic acid [(1S,3R)-ACPD] and the group I mGlu receptor agonist 3,5-dihydroxyphenylglycine (3,5-DHPG). The antagonists (+)MCPG, AIDA and CBPG were also neuroprotective in vivo, because i. c.v. administration reduced CA1 pyramidal cell degeneration examined 7 days following transient carotid occlusion in gerbils. Our results point to a role of mGlu1 receptors in the pathological mechanisms responsible for postischaemic neuronal death and propose a new target for neuroprotection.

Prokineticins are neuroprotective in models of cerebral ischemia and ischemic tolerance in vitro

“…Neuroprotective effects of Bv8 (PK2) in mixed murine cortical cultures and rat organotypic hippocampal slices exposed to oxygen and glucose deprivation (OGD) Bv8 can be used as a suitable pharmacological tool to investigate the effects of PK2 in vitro and in vivo (Giannini et al, 2009;Severini et al, 2015). To investigate the possible neuroprotective effects of Bv8 we carried out experiments in cultured murine cortical cells exposed to OGD, an in vitro model of focal cerebral ischemia routinely used in our lab (Pellegrini-Giampietro et al, 1999a). We have demonstrated that OGD induces necrotic neuronal death in this system, as detected by the appareance of necrotic ultrastructural features 24 h later and the lack of caspase-3 activation (Moroni et al, 2001).…”

“…Cultures of mixed murine cortical cells were exposed to oxygenglucose deprivation (OGD) as previously described in detail (Pellegrini-Giampietro et al, 1999a, 1999b. Briefly, culture medium was replaced by a glucose-free balanced salt solution saturated with 95% N2/5% CO2 and heated to 37 C. Multiwells were then sealed into an airtight incubation chamber equipped with inlet and outlet valves and 95% N2/5% CO2 was blown through the chamber for 10 min to ensure maximal removal of oxygen.…”

“…OGD was terminated by removing the cultures from the chamber, replacing the exposure solution with oxygenated medium and returning the multiwells to the incubator under normoxic conditions. The extent of cell detah was quantitatively evaluated by measuring the amount of LDH released from injured cells into culture media 24 h following exposure to OGD, as previously described (Pellegrini-Giampietro et al, 1999a, 1999b. The LDH level corresponding to complete neuronal death (with no glial death) was determined for each experiment by assaying sister cultures exposed to 1 mM glutamate for 24 h. Background LDH release was determined in control cultures not exposed to OGD and subtracted from all experimental values.…”

“…Organotypic hippocampal slice cultures were prepared from 8-day-old rats, used at 14 DIV and exposed to OGD as previously reported in detail (Pellegrini-Giampietro et al, 1999a, 1999bGerace et al, 2012a). Briefly: the slices were pre-incubated for 5 min in serum-free medium and then subjected to OGD by exposure to a serum-free medium devoid of glucose and previously saturated with 95% N2/5% CO2.…”

Group I metabotropic glutamate receptors stimulate the activity of poly(ADP-ribose) polymerase in mammalian mGlu1-transfected cells and in cortical cell cultures

“…It should be noted, however, that OGD exposure in the present study was much milder (40 vs. 60 min) and that PARP inhibitors are known to be efficacious only when excitotoxic or ischemic insults are particularly intense and presumably necrotic (Bonfoco et al, 1995;Meli et al, 2004). In cultured cortical cells, DHPG by itself is not toxic but exacerbates LDH release and neuronal damage following exposure to OGD (Pellegrini-Giampietro et al, 1999a). Our results show that DPQ was able to completely abolish the component of OGD injury evoked by DHPG, strongly suggesting that PARP overactivation is responsible for the neuronal damage evoked by DHPG in this model.…”