Cerebellar and cortical TLR4 activation and behavioral impairments in Wernicke-Korsakoff Syndrome: Pharmacological effects of oleoylethanolamide.

Wernicke-Korsakoff Syndrome (WKS) is a neuropsychiatric disorder whose etiology is a thiamine deficiency (TD), with alcoholism being the main underlying cause. Previous evidence suggests the presence of initial neuroinflammation and oxidative/nitrosative stress in the physiopathology, although the specific molecular mechanisms underlying TD-induced brain damage and behavioral disabilities are unknown. We explored the specific role of the innate immune receptor TLR4 in three murine models of WKS, based on the combination of a thiamine-deficient diet and pyrithiamine injections (0.25 mg/kg, i.p.) over time. The Symptomatic Model (SM) allowed us to describe the complete neurological/neurobehavioral symptomatology over 16 days of TD. Animals showed an upregulation of the TLR4 signaling pathway both in the frontal cortex (FC) and cerebellum and clear motor impairments related with cerebellar dysfunction. However, in the Pre-Symptomatic Model (PSM), 12 days of TD induced the TLR4 pathway upregulation in the FC, which correlated with disinhibited-like behavior, but not in the cerebellum, and no motor impairments. In addition, we tested the effects of the biolipid oleoylethanolamide (OEA, 10 mg/kg, i.p., once daily, starting before any symptom of the pathology is manifested) through the Glucose-Precipitated Model (GPM), which was generated by glucose loading (5 g/kg, i.v., last day) in thiamine-deficient animals to accelerate damage. Pretreatment with OEA prevented the TLR4-induced signature in the FC, as well as an underlying incipient memory disability and disinhibited-like behavior. This study suggests a key role for TLR4 in TD-induced neuroinflammation in the FC and cerebellum, and it reveals different vulnerability of these brain regions in WKS over time. Pre-treatment with OEA counteracts TD-induced TLR4-associated neuroinflammation and may serve as co-adjuvant therapy to prevent WKS-induced neurobehavioral alterations.

Sex-dependent influence of chronic mild stress (CMS) on voluntary alcohol consumption; study of neurobiological consequences.

Alcohol use disorder and depression are highly comorbid, and both conditions exhibit important sexual dimorphisms. Here, we aimed to investigate voluntary alcohol consumption after 6weeks of chronic mild stress (CMS) in Wistar rats - employed as an animal model of depression. Male and female rats were investigated, and changes in several molecular markers were analysed in frontal cortex (FCx) and hippocampal formation (HF). CMS induced depressive-like responses in the forced swimming test - increased immobility time - in male and female animals, without affecting anhedonia (sucrose preference test) nor motor activity (holeboard); body weight gain and food intake were diminished only among CMS males. Voluntary alcohol consumption was evaluated in a two-bottle choice paradigm (ethanol 20% versus tap water) for 4 consecutive days; females exhibited a higher preference for alcohol compared to male animals. In particular, alcohol consumption was significantly higher among CMS females compared to CMS male animals. Remarkably, similar changes in both male and female animals exposed to CMS were observed regarding the expression levels of NCAM-140KDa (decrease), GFAP and CB1R expression (increase) within the FCx as well as for HF PSD-95 levels (increase). However, contrasting effects in males and females were reported in relation to synaptophysin (SYN) protein levels within the FCx, HF CB1R expression (a decrease among male animals but an increase in females); while the opposite pattern was observed for NCAM-140KDa protein levels in the HF. A decrease in CB2R expression was only observed in the HF of CMS-females. The present study suggests that male and female animals might be differentially affected by CMS regarding later voluntary alcohol consumption. In this initial approach, cortical SYN, and NCAM-140KDa, CB1R and CB2R expression within the HF have arisen as potential candidates to explain such sex differences in behaviour. However, the depression-alcoholism relationship still deserves further investigation.

Potential Therapeutic Value of a Novel FAAH Inhibitor for the Treatment of Anxiety.

Anxiety disorders are among the most prevalent psychiatric diseases with high personal costs and a remarkable socio-economic burden. However, current treatment of anxiety is far from satisfactory. Novel pharmacological targets have emerged in the recent years, and attention has focused on the endocannabinoid (eCB) system, given the increasing evidence that supports its central role in emotion, coping with stress and anxiety. In the management of anxiety disorders, drug development strategies have left apart the direct activation of type-1 cannabinoid receptors to indirectly enhance eCB signalling through the inhibition of eCB deactivation, that is, the inhibition of the fatty acid amide hydrolase (FAAH) enzyme. In the present study, we provide evidence for the anxiolytic-like properties of a novel, potent and selective reversible inhibitor of FAAH, ST4070, orally administered to rodents. ST4070 (3 to 30 mg/kg per os) administered to CD1 male mice induced an increase of time spent in the exploration of the open arms of the elevated-plus maze. A partial reduction of anxiety-related behaviour by ST4070 was also obtained in Wistar male rats, which moderately intensified the time spent in the illuminated compartment of the light-dark box. ST4070 clearly inhibited FAAH activity and augmented the levels of two of its substrates, N-arachidonoylethanolamine (anandamide) and N-palmitoylethanolamine, in anxiety-relevant brain regions. Altogether, ST4070 offers a promising anxiolytic-like profile in preclinical studies, although further studies are warranted to clearly demonstrate its efficacy in the clinic management of anxiety disorders.

Sex-dependent psychoneuroendocrine effects of THC and MDMA in an animal model of adolescent drug consumption.

Ecstasy is a drug that is usually consumed by young people at the weekends and frequently, in combination with cannabis. In the present study we have investigated the long-term effects of administering increasing doses of delta-9-tetrahydrocannabinol [THC; 2.5, 5, 10 mg/kg; i.p.] from postnatal day (pnd) 28 to 45, alone and/or in conjunction with 3,4-methylenedioxymethamphetamine [MDMA; two daily doses of 10 mg/kg every 5 days; s.c.] from pnd 30 to 45, in both male and female Wistar rats. When tested one day after the end of the pharmacological treatment (pnd 46), MDMA administration induced a reduction in directed exploration in the holeboard test and an increase in open-arm exploration in an elevated plus maze. In the long-term, cognitive functions in the novel object test were seen to be disrupted by THC administration to female but not male rats. In the prepulse inhibition test, MDMA-treated animals showed a decrease in prepulse inhibition at the most intense prepulse studied (80 dB), whereas in combination with THC it induced a similar decrease at 75 dB. THC decreased hippocampal Arc expression in both sexes, while in the frontal cortex this reduction was only evident in females. MDMA induced a reduction in ERK1/2 immunoreactivity in the frontal cortex of male but not female animals, and THC decreased prepro-orexin mRNA levels in the hypothalamus of males, although this effect was prevented when the animals also received MDMA. The results presented indicate that adolescent exposure to THC and/or MDMA induces long-term, sex-dependent psychophysiological alterations and they reveal functional interactions between the two drugs.

Endocannabinoid system and psychiatry: in search of a neurobiological basis for detrimental and potential therapeutic effects.

Public concern on mental health has noticeably increased given the high prevalence of neuropsychiatric disorders. Cognition and emotionality are the most affected functions in neuropsychiatric disorders, i.e., anxiety disorders, depression, and schizophrenia. In this review, most relevant literature on the role of the endocannabinoid (eCB) system in neuropsychiatric disorders will be presented. Evidence from clinical and animal studies is provided for the participation of CB1 and CB2 receptors (CB1R and CB2R) in the above mentioned neuropsychiatric disorders. CBRs are crucial in some of the emotional and cognitive impairments reported, although more research is required to understand the specific role of the eCB system in neuropsychiatric disorders. Cannabidiol (CBD), the main non-psychotropic component of the Cannabis sativa plant, has shown therapeutic potential in several neuropsychiatric disorders. Although further studies are needed, recent studies indicate that CBD therapeutic effects may partially depend on facilitation of eCB-mediated neurotransmission. Last but not least, this review includes recent findings on the role of the eCB system in eating disorders. A deregulation of the eCB system has been proposed to be in the bases of several neuropsychiatric disorders, including eating disorders. Cannabis consumption has been related to the appearance of psychotic symptoms and schizophrenia. In contrast, the pharmacological manipulation of this eCB system has been proposed as a potential strategy for the treatment of anxiety disorders, depression, and anorexia nervosa. In conclusion, the eCB system plays a critical role in psychiatry; however, detrimental consequences of manipulating this endogenous system cannot be underestimated over the potential and promising perspectives of its therapeutic manipulation.

Chronic treatment with CP 55,940 during the peri-adolescent period differentially affects the behavioural responses of male and female rats in adulthood.

RATIONALE: Despite the increasing use of cannabis among adolescents, there is scarce information about the long-term effects of cannabinoid receptor agonists in appropriate animal models. OBJECTIVES: We aimed to investigate the behavioural features of adult male and female Wistar rats that had been exposed to a chronic treatment with the cannabinoid receptor agonist CP 55,940 (CP) during the juvenile period. METHODS: CP (0.4 mg/kg i.p.) or its corresponding vehicle was administered once daily, from day 35 to day 45. In adulthood, the animals were tested in the holeboard, the open field and the elevated plus-maze, under different stress (illumination) conditions. After a resting period, the serum corticosterone levels (radioimmunoassay) of the animals were measured. The effects of CP on food intake and somatic growth were monitored throughout the experimental period. RESULTS: The CP treatment induced significant sex-dependent effects on holeboard activity, as well as a decrease in the level of emotionality/anxiety in the open field and in the plus-maze. The animals receiving CP also showed diminished food intake and body weights during the treatment period, but both parameters recovered normal values during the period after treatment. No significant effect of the CP treatment on corticosterone levels was found. CONCLUSIONS: The results demonstrate that chronic administration of CP during the peri-adolescent period resulted in marked behavioural effects in adulthood. The nature of these effects depended on the sex of the animals and on the specific behavioural test. The possible neurobiological substrates underlying the effects of CP are discussed.