Biol Psychiatry. 2015 Apr 14. pii: S0006-3223(15)00314-5. doi: 10.1016/j.biopsych.2015.03.033. [Epub ahead of print]
Anxiety, Stress, and Fear Response in Mice with Reduced Endocannabinoid Levels.
Jenniches I1, Ternes S1, Albayram O1, Otte DM1, Bach K1, Bindila L2, Michel K1, Lutz B2, Bilkei-Gorzo A2, Zimmer A3.
1Institute of Molecular Psychiatry, University of Bonn, Bonn, Germany.; Institute of Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany.
2Institute of Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany.
3Institute of Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany.. Electronic address: a.zimmer@uni-bonn.de.
BACKGROUND:
Disruption of the endocannabinoid system through pharmacological or genetic invalidation of cannabinoid CB1 receptors has been linked to depression in humans and depression-like behaviors in mice. The two main endogenous cannabinoids, anandamide and 2-arachidonoyl glycerol (2-AG), are produced on demand from phospholipids. The pathways and enzymes involved in endocannabinoid biosynthesis thus play a major role in regulating the activity of this system. This study investigates the role of the main 2-AG producing enzyme diacylglycerol lipase a (DAGL-a).
METHODS:
We generated and used knockout mice lacking DAGL-a (Dagla-/-) to assess the behavioral consequences of reduced endocannabinoid levels in the brain. We performed different behavior tests to determine anxiety- and depression-related behavioral changes in Dagla-/- mice. We also analyzed expression of genes related to the endocannabinoid system via real-time polymerase chain reaction and used the mitotic marker 5-bromo-2'-deoxyuridine to analyze adult neurogenesis.
RESULTS:
Dagla-/- animals show an 80% reduction of brain 2-AG levels but also a reduction in cortical and amygdalar anandamide. The behavioral changes induced by Dagla deletion include a reduced exploration of the central area of the open field, a maternal neglect behavior, a fear extinction deficit, increased behavioral despair, increased anxiety-related behaviors in the light/dark box, and reduced hippocampal neurogenesis. Some of these behavioral changes resemble those observed in animals lacking the CB1 receptor.
CONCLUSIONS:
Our findings demonstrate that the deletion of Dagla adversely affects the emotional state of animals and results in enhanced anxiety, stress, and fear responses.
Exp Eye Res. 2015 May 16. pii: S0014-4835(15)00155-4. doi: 10.1016/j.exer.2015.05.007. [Epub ahead of print]
Synthetic and endogenous cannabinoids protect retinal neurons from AMPA excitotoxicity in vivo, via activation of CB1 receptors: Involvement of PI3K/Akt and MEK/ERK signaling pathways.
Kokona D1, Thermos K2.
1Department of Pharmacology, School of Medicine, University of Crete, Heraklion, Crete 71003 GR, Greece. Electronic address: despina.kokona@insel.ch.
2Department of Pharmacology, School of Medicine, University of Crete, Heraklion, Crete 71003 GR, Greece. Electronic address: thermos@med.uoc.gr.
Cannabinoids have been suggested to protect retinal ganglion cells in different models of toxicity, but their effects on other retinal neurons are poorly known. We investigated the neuroprotective actions of the endocannabinoid N-arachidonoyl ethanolamine (Anandamide/AEA) and the synthetic cannabinoids R1-Methanandamide (MethAEA) and HU-210, in an in vivo retinal model of AMPA excitotoxicity, and the mechanisms involved in the neuroprotection. Sprague-Dawley rats were intravitreally injected with PBS or AMPA in the absence or presence of the cannabinoid agonists. Brain nitric oxide synthase (bNOS) and choline acetyltransferase (ChAT) immunoreactivity (IR), as well as TUNEL staining, assessed the AMPA-induced retinal amacrine cell loss and the dose-dependent neuroprotection afforded by cannabinoids. The CB1 receptor selective antagonist AM251 and the PI3K/Akt inhibitor wortmannin reversed the cannabinoid-induced neuroprotection, suggesting the involvement of CB1 receptors and the PI3K/Akt pathway in cannabinoids' actions. Experiments with the CB2 agonist JWH015 and [3H]CP55940 radioligand binding suggested that the CB2 receptor is not involved in the neuroprotection. AEA and HU-210 induced phosphorylation of Akt but only AEA induced phosphorylation of ERK1/2 kinases, as revealed by western blot analysis. To investigate the role of caspase-3 in the AMPA-induced cell death, the caspase-3 inhibitor Z-DEVD-FMK was co-injected with AMPA. Z-DEVD-FMK had no effect on AMPA excitotoxicity. Moreover, no difference was observed in the phosphorylation of SAPK/JNK kinases between PBS- and AMPA-treated retinas. These results suggest that endogenous and synthetic cannabinoids protect retinal amacrine neurons from AMPA excitotoxicity in vivo via a mechanism involving the CB1 receptors, and the PI3K/Akt and/or MEK/ERK1/2 signaling pathways. |
