Acute, chronic and withdrawal effects of the cannabinoid receptor agonist WIN55212‐2 on the sequential activation of MAPK/Raf‐MEK‐ERK signaling in the rat cerebral frontal cortex: Short‐term regulation by intrinsic and extrinsic pathways

Abstract

The cannabinoids (CB) modulate the extracellular signal-regulated kinase (ERK), leading to various forms of plasticity in the brain. Little is known, however, on the in vivo short- and long-term activation and regulation of the components of mitogen-activated protein kinase (MAPK)/ERK signaling by CB. The CB agonist WIN55212-2 (8 mg/kg) increased the immunodensities of phosphorylated c-Raf-1 (42%), MEK1/2 (63%), ERK1 (24%), and ERK2 (28%) in the rat cerebral frontal cortex. These effects were antagonized by SR141716A (rimonabant, 10 mg/kg), a selective CB(1) receptor antagonist. Repeated WIN55212-2 treatment (2-8 mg/kg for 5 days) resulted in tachyphylaxis to the acute activation of Raf-MEK-ERK signaling. Acute WIN55212-2 also induced a hypothermic effect in rats, which was reduced after repeated administration (tolerance). Treatment with SR141716A after chronic WIN55212-2 resulted in the expected cannabinoid withdrawal syndrome, without concomitant alterations in the phosphorylation state of c-Raf-1, MEK1/2, or ERK1/2. Pretreatment with SL327 (20 mg/kg, a MEK1/2 inhibitor) increased the basal phosphorylation of c-Raf-1 (40%) and MEK1/2 (74%; feedback regulation) and fully prevented the up-regulation of ERK1/2 (23-31%) induced by WIN55212-2. Pretreatment with MK801 (1 mg/kg, a NMDA receptor antagonist) effectively blocked the up-regulation c-Raf-1 (41%), MEK1/2 (57%) and ERK1/2 (25-30%) induced by the CB agonist. The main findings demonstrate that the acute stimulation of CB(1) receptors in the frontal cortex results in the sequential phosphorylation of Raf-MEK-ERK cascade, in which c-Raf-1 activation (rate-limiting process) plays a crucial role. Moreover, the in vivo stimulating effect of WIN55212-2 on Raf-MEK-ERK signaling is under the extrinsic regulation of an excitatory glutamatergic mechanism.

N-Arachidonoyl-l-Serine is Neuroprotective after Traumatic Brain Injury by Reducing Apoptosis

“…These effects may explain our findings on the reduction of cerebral edema in the AraS-treated mice. In addition, CB1 receptor agonists were shown to activate Akt (Gomez del Pulgar et al, 2000) and ERK (Moranta et al 2007), which participate in prosurvival processes, including those related to neuroprotection (Pignataro et al, 2008;Yune et al, 2008). Our present results, in agreement with those of Milman et al (2006), suggest that in the brain, as in endothelial cells, the novel The effect of AraS treatment on caspase-3 activity (expressed as fluorescence units of DEVD-AFC cleaved product) in the brains of shamoperated controls and CHI animals treated with vehicle, AraS, AraS + SR141716A, AraS + SR144528, or AraS + capsazepine 72 hours after injury (&P < 0.05 versus AraS, ## P < 0.01 versus vehicle, ***P < 0.001 versus sham).…”

Regulation of Fas receptor/Fas‐asssociated protein with death domain apoptotic complex and associated signalling systems by cannabinoid receptors in the mouse brain

“…Control mice received drug vehicle (Cremophor : ethanol : water, 1:1:18 proportion or DMSO : Tween 80 : water, 1:1:8 proportion; 2 mL·kg −1 , i.p., 1 h). The doses of WIN55,212‐2, rimonabant and JWH133 were chosen from earlier studies (Moranta et al ., 2007; see also Barna et al ., 2009).…”

“…For the chronic treatment with WIN55212‐2, groups of mice were injected (i.p.) twice daily for 5 days with increasing doses of the agonist (1–8 mg·kg −1 ; Moranta et al ., 2007). The first group of mice was killed 1 h after the last dose of WIN55212‐2 to assess the brain content of target proteins.…”

“…The second group of mice was injected with rimonabant (10 mg·kg −1 , i.p.) to precipitate and evaluate the cannabinoid withdrawal syndrome (Moranta et al ., 2007). Finally, the third group of mice was killed 1 h after rimonabant‐precipitated withdrawal to quantify various signalling proteins in the brain.…”

The dual neuroprotective–neurotoxic profile of cannabinoid drugs

“…Maresz et al ., 2007; Zhang et al ., 2007; Fernandez‐Ruiz et al ., 2008) and neurogenesis (Galve‐Roperh et al ., 2007). It was also suggested that CB 1 receptors activate intracellular mechanisms such as the phosphatidylinositol 3‐kinase (PI3K/Akt) (Gomez Del Pulgar et al ., 2002; Molina‐Holgado et al ., 2005; Ozaita et al ., 2007) and ERK (Valjent et al ., 2001; Derkinderen et al ., 2003; Tonini et al ., 2006; Moranta et al ., 2007) pathways that are considered as survival signals and may contribute to the protective effects of CBs. Other neuroprotective mechanisms of CBs in either healthy or pathologic conditions were also suggested (for recent reviews, see Pacher et al ., 2006; Di Marzo, 2008; Fowler et al ., 2010; Viscomi et al ., 2010).…”