Pharmacological induction of Heat Shock Protein 70 by celastrol protects motoneurons from excitotoxicity in rat spinal cord in vitro

Abstract

The secondary phase of spinal cord injury arising after the primary lesion largely extends the damage severity with delayed negative consequences for sensory‐motor pathways. It is, therefore, important to find out if enhancing intrinsic mechanisms of neuroprotection can spare motoneurons that are very vulnerable cells. This issue was investigated with an in vitro model of rat spinal cord excitotoxicity monitored for up to 24 hr after the primary injury evoked by kainate. This study sought to pharmacologically boost the expression of heat shock proteins (HSP) to protect spinal motoneurons using celastrol to investigate if the rat spinal cord can upregulate HSP as neuroprotective mechanism. Despite its narrow range of drug safety in vitro, celastrol was not toxic to the rat spinal cord at 0.75 μM concentration and enhanced the expression of HSP70 by motoneurons. When celastrol was applied either before or after kainate, the number of dead motoneurons was significantly decreased and the nuclear localization of the cell death biomarker AIF strongly inhibited. Nevertheless, electrophysiological recording showed that protection of lumbar motor networks by celastrol was rather limited as reflex activity was impaired and fictive locomotion largely depressed, suggesting that functional deficit persisted, though the networks could express slow rhythmic oscillations. While our data do not exclude further recovery at later times beyond the experimental observations, the present results indicate that the upregulated expression of HSP in the aftermath of acute injury may be an interesting avenue for early protection of spinal motoneurons.

Nicotine Neurotoxicity Involves Low Wnt1 Signaling in Spinal Locomotor Networks of the Postnatal Rodent Spinal Cord

“…of a 10% w/v solution). Whole spinal cord preparations were gently removed in oxygenated Krebs solution (in mM; 113 NaCl, 4.5 KCl, 1 MgCl 2 .7H 2 O, 2 CaCl 2 , 1 NaH 2 PO 4 , 25 NaHCO 3 , 11 glucose; gassed with 95% oxygen (O 2 ) and 5% carbon dioxide (CO 2 ); pH 7.4 at room temperature, flowing at 7.5 mL/min) as reported earlier [2,62,63] and were kept in Krebs solution for 2 h to reach functional recovery.…”

Heat Shock Protein 70 (HSP70) Induction: Chaperonotherapy for Neuroprotection after Brain Injury

“…Celastrol, a quinone methide family member isolated from the Thunder God Vine, has been shown to upregulate HSF-1, which, in turn, leads to HSP induction; this has been shown in human neuronal cells [ 130 ]. Celastrol has been shown to protect motor neurons from kainic acid induced excitotoxicity while upregulating HSPs [ 131 ]. Celastrol has also been shown to improve outcome in a stroke model, but this study did not explore whether this was related to HSP induction [ 132 ].…”

Glia in amyotrophic lateral sclerosis and spinal cord injury: common therapeutic targets

“…A number of neurodegenerative disease models, including those of ALS, have shown neuroprotective function of arimoclomol, leading to clinical testing of its therapeutic potential (67,68). Arimoclomol is a coinducer of heat shock proteins (HSP), molecular chaperones involved in heat shock response, a major defense mechanism against stress or injury (69). Similarly, natural compound celastrol, which induces HSP, has been tested as a neuroprotectant in different animal and in vitro models of neurodegeneration, including ALS and SCI, with a beneficial outcome (69,70).…”

“…Arimoclomol is a coinducer of heat shock proteins (HSP), molecular chaperones involved in heat shock response, a major defense mechanism against stress or injury (69). Similarly, natural compound celastrol, which induces HSP, has been tested as a neuroprotectant in different animal and in vitro models of neurodegeneration, including ALS and SCI, with a beneficial outcome (69,70). Other mechanisms of action of celastrol could be relevant for both ALS and SCI, including its anti-inflammatory role (71).…”