Endogenous cannabinoids mediate the effect of BDNF at CA1 inhibitory synapses in the hippocampus

CBD enhances the cognitive score of adolescent rats prenatally exposed to THC and fine-tunes relevant effectors of hippocampal plasticity

Introduction: An altered neurodevelopmental trajectory associated with prenatal exposure to ∆-9-tetrahydrocannabinol (THC) leads to aberrant cognitive processing through a perturbation in the effectors of hippocampal plasticity in the juvenile offspring. As adolescence presents a unique window of opportunity for "brain reprogramming", we aimed at assessing the role of the non-psychoactive phytocannabinoid cannabidiol (CBD) as a rescue strategy to temper prenatal THC-induced harm. Methods: To this aim, Wistar rats prenatally exposed to THC (2 mg/kg s.c.) or vehicle (gestational days 5-20) were tested for specific indexes of spatial and configural memory in the reinforcement-motivated Can test and in the aversion-driven Barnes maze test during adolescence. Markers of hippocampal excitatory plasticity and endocannabinoid signaling-NMDAR subunits NR1 and 2A-, mGluR5-, and their respective scaffold proteins PSD95- and Homer 1-; CB1R- and the neuromodulatory protein HINT1 mRNA levels were evaluated. CBD (40 mg/kg i.p.) was administered to the adolescent offspring before the cognitive tasks. Results: The present results show that prenatal THC impairs hippocampal memory functions and the underlying synaptic plasticity; CBD is able to mitigate cognitive impairment in both reinforcement- and aversion-related tasks and the neuroadaptation of hippocampal excitatory synapses and CB1R-related signaling. Discussion: While this research shows CBD potential in dampening prenatal THC-induced consequences, we point out the urgency to curb cannabis use during pregnancy in order to avoid detrimental bio-behavioral outcomes in the offspring.

Ketogenic and Modified Mediterranean Diet as a Tool to Counteract Neuroinflammation in Multiple Sclerosis: Nutritional Suggestions

Ketogenic Diet is a nutritional pattern often used as dietotherapy in inflammatory diseases, including neurological disorders. Applied on epileptic children since 1920, in recent years it has been taken into account again as a tool to both reduce inflammatory burdens and ameliorate the nutritional status of patients affected by different pathologies. Multiple sclerosis (MS) is considered an immune-mediated neuro-inflammatory disease and diet is a possible factor in its pathogenesis. The aim of this work is to investigate the main potential targets of MS-related impairments, in particular the cognitive deficits, focusing on the alteration of biomarkers such as the Brain Derived-Neurotrophic Factor and the Tryptophan/Kynurenine ratio that could play a role on neuroprotection and thus on MS progression. Furthermore, we here propose nutritional suggestions which are useful in the development of a ketogenic diet protocol that takes advantage of the anti-inflammatory properties of low-carbohydrate foods from the Mediterranean diet to be applied to subjects with MS. In conclusion, this approach will allow one to develop the ketogenic diet combined with a modified Mediterranean diet as a possible tool to improve neuroinflammation in multiple sclerosis.

Exercise Training Improves Memory Performance in Older Adults: A Narrative Review of Evidence and Possible Mechanisms

Exercise, neurotransmitters, growth factors, myokines, and potential effects on the brain.

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Cannabinoid receptor agonist WIN55212-2 reduces unpredictable mild stress-induced depressive behavior of rats

Background

Depression is a neurological disorder characterized by persistent low mood. A number of studies have suggested that the use of type 1 cannabinoid receptor (CB1R) agonists can reduce depressive behavior, but its effect on the depressive behavior and nerve damage of rats exposed to chronic unpredictable mild stress (CUMS) has not been reported.

Methods

Rats were exposed to CUMS for 4 weeks to induce depressive behavior. Male Sprague-Dawley (SD) rats aged 6–8 weeks were randomly divided into six groups: control group (control), depression group (CUMS), depression + fluoxetine group (Flu), depression + WIN55212-2 group (WIN), depression + NF-κB inhibitor group (PDTC), and depression + WIN + PDTC group (WIN + PDTC). We performed four behavioral experiments test to evaluate the depressive behaviors of rats. Hematoxylin and eosin (HE) and Nissl staining were performed to observe the neuron structures of the hippocampus. Enzyme-linked immunosorbent assay (ELISA) was used to measure the concentrations of interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and cyclooxygenase-2 (COX-2). Biochemical experiments were performed to evaluate the concentrations of nitric oxide (NO), malondialdehyde (MDA), reactive oxygen species (ROS), and superoxide dismutase (SOD). Fluorescence quantitative PCR was used to detect the mRNA expression of brain-derived neurotrophic factor (BDNF), tyrosine kinase receptor B (TrkB), and inducible nitric oxide synthase (iNOS) in the hippocampus, and western blot was performed to detect protein expression levels related to the NF-κB signaling pathway in the hippocampus.

Results

Compared with the normal control group, CUMS significantly induced abnormal behaviors in stressed rats. The concentrations of pro-inflammatory factors and oxidative stress injury factors in the hippocampus of the CUMS group increased significantly. The interventions of Flu, WIN, and PDTC significantly reduced neuroinflammation and oxidative stress injury. Compared with the WIN group, the WIN + PDTC intervention group had better results. In addition, WIN could significantly inhibit the activation of the NF-κB signaling pathway.

Conclusions

This study showed that cannabinoid receptor agonists can reduce the CUMS-induced depressive behaviors of rats by blocking the NF-κB signaling pathway to alleviate neuroinflammation and oxidative stress injury.

Central administration of endocannabinoids exerts bimodal effects in food intake of rainbow trout

The endocannabinoid system (ECs) is known to participate in several processes in mammals related to synaptic signaling including regulation of food intake, appetite and energy balance. In fish, the relationship of ECs with food intake regulation is poorly understood. In the present study, we assessed in rainbow trout Oncorhynchus mykiss the effect of intracerebroventricular administration (ICV) of low and high doses of the endocannabinoids anandamide (AEA) and 2-arachidonoylglycerol (2-AG) on food intake. We assessed endocannabinoid levels in hypothalamus, telencephalon and plasma as well as the effect of AEA and 2-AG administration at central level on gene expression of receptors involved in ECs (cnr1, gpr55 and trpv1) and markers of neural activity (fos, ntrk2 and GABA-related genes). The results obtained indicate that whereas high doses of endocannabinoids did not elicit changes in food intake levels, low doses of the endocannabinoids produce an orexigenic effect that could be due to a possible inhibition of gabaergic neurotransmission and the modulation of neural plasticity in brain areas related to appetite control, such as hypothalamus and telencephalon.

BDNF Impact on Biological Markers of Depression-Role of Physical Exercise and Training

Depression is the most common and devastating psychiatric disorder in the world. Its symptoms, especially during the pandemic, are observed in all age groups. Exercise training (ET) is well known as a non-pharmacological strategy to alleviate clinical depression. The brain-derived neurotrophic factor (BDNF) is one of the biological factors whose expression and secretion are intensified in response to ET. BDNF is also secreted by contracted skeletal muscle that likely exerts para-, auto- and endocrine effects, supporting the crosstalk between skeletal muscle and other distant organs/tissues, such as the nervous system. This finding suggests that they communicate and work together to induce improvements on mood, cognition, and learning processes as BDNF is the main player in the neurogenesis, growth, and survival of neurons. Therefore, BDNF has been recognized as a therapeutic factor in clinical depression, especially in response to ET. The underlying mechanisms through which ET impacts depression are varied. The aim of this review was to provide information of the biological markers of depression such as monoamines, tryptophan, endocannabinoids, markers of inflammatory processes (oxidative stress and cytokines) stress and sex hormones and their relationship to BDNF. In addition, we reviewed the effects of ET on BNDF expression and how it impacts depression as well as the potential mechanisms mediating this process, providing a better understanding of underlying ET-related mechanisms in depression.

Brain-Derived Neurotrophic Factor as a Clinical Biomarker in Predicting the Development of Post-Stroke Depression: A Review of Evidence

Studying the relationship between brain-derived neurotrophic factor (BDNF) and post-stroke depression (PSD) may help determine the potential for depression in stroke patients at the earliest stage possible. Current research has identified changes in BDNF levels in PSD patients. Thus, this article was intended as a review of evidence with respect to changes in the expression of BDNF in patients with PSD by integrating extant findings.

We conducted a search in the electronic databases PubMed, EMBASE, and PsycINFO (all records from January 1, 2000, through October 20, 2020) using keywords: “brain-derived neurotrophic factor OR BDNF,” “post-stroke depression OR PSD,” “expression level,” “association,” and “relationship.” Returned articles were considered for inclusion in this review if they were empirical studies investigating the association between BDNF expression and PSD.

Seven original papers were selected for review and revealed inconsistent findings. Five out of seven studies reported a significant decrease in BDNF levels in PSD patients at a certain stage (most likely the early stage) of stroke after admission, whereas the other two showed contrasting findings.

Overall, this review reveals associations between changes in serum BDNF levels and depression following stroke. Whether serum BDNF levels, especially in the early phase of stroke, can be a potentially effective biomarker for predicting the risk of subsequent PSD development is still open to debate.

Lights on Endocannabinoid-Mediated Synaptic Potentiation

The endocannabinoid (eCB) system is a lipid-based neurotransmitter complex that plays crucial roles in the neural control of learning and memory. The current model of eCB-mediated retrograde signaling is that eCBs released from postsynaptic elements travel retrogradely to presynaptic axon terminals, where they activate cannabinoid type-1 receptors (CB₁Rs) and ultimately decrease neurotransmitter release on a short- or long-term scale. An increasing body of evidence has enlarged this view and shows that eCBs, besides depressing synaptic transmission, are also able to increase neurotransmitter release at multiple synapses of the brain. This indicates that eCBs act as bidirectional regulators of synaptic transmission and plasticity. Recently, studies unveiled links between the expression of eCB-mediated long-term potentiation (eCB-LTP) and learning, and between its dysregulation and several pathologies. In this review article, we first distinguish the various forms of eCB-LTP based on their mechanisms, resulting from homosynaptically or heterosynaptically-mediated processes. Next, we consider the neuromodulation of eCB-LTP, its behavioral impact on learning and memory, and finally, eCB-LTP disruptions in various pathologies and its potential as a therapeutic target in disorders such as stress coping, addiction, Alzheimer’s and Parkinson’s disease, and pain. Cannabis is gaining popularity as a recreational substance as well as a medicine, and multiple eCB-based drugs are under development. In this context, it is critical to understand eCB-mediated signaling in its multi-faceted complexity. Indeed, the bidirectional nature of eCB-based neuromodulation may offer an important key to interpret the functions of the eCB system and how it is impacted by cannabis and other drugs.

A Systematic Review of the Effects of Perinatal Alcohol Exposure and Perinatal Marijuana Exposure on Adult Neurogenesis in the Dentate Gyrus

BACKGROUND

Marijuana and alcohol are both substances that, when used during pregnancy, may have profound effects on the developing fetus. There is evidence to suggest that both drugs have the capacity to affect working memory, one function of the hippocampal formation; however, there is a paucity of data on how perinatal exposure to alcohol or cannabis impacts the process of adult neurogenesis.

METHODS

This systematic review examines immunohistochemical data from adult rat and mouse models that assess perinatal alcohol or perinatal marijuana exposure. A comprehensive list of search terms was designed and used to search 3 separate databases. All results were imported to Mendeley and screened by 2 authors. Consensus was reached on a set of final papers that met the inclusion criteria, and their results were summarized.

RESULTS

Twelve papers were identified as relevant, 10 of which pertained to the effects of perinatal alcohol on the adult hippocampus, and 2 pertained to the effects of perinatal marijuana on the adult hippocampus. Cellular proliferation in the dentate gyrus was not affected in adult rats and mice exposed to alcohol perinatally. In general, perinatal alcohol exposure did not have a significant and reliable effect on the maturation and survival of adult born granule neurons in the dentate gyrus. In contrast, interneuron numbers appear to be reduced in the dentate gyrus of adult rats and mice exposed perinatally to alcohol. Perinatal marijuana exposure was also found to reduce inhibitory interneuron numbers in the dentate gyrus.

CONCLUSIONS

Perinatal alcohol exposure and perinatal marijuana exposure both act on inhibitory interneurons in the hippocampal formation of adult rats. These findings suggest simultaneous perinatal alcohol and marijuana exposure (SAM) may have a dramatic impact on inhibitory processes in the dentate gyrus.