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In recent years, there has been growing evidence that cannabinoids have promising medicinal and pharmacological effects. However, the growing interest in medical cannabis highlights the need to better understand brain alterations linking phytocannabinoids or synthetic cannabinoids to clinical and behavioral phenotypes. Therefore, the aim of this study was to investigate the effects of long-term WIN 55,212-2 treatment—with and without prolonged abstinence—on cerebral metabolism and memory function in healthy wildtype mice. Adult C57BI/6J mice were divided into two treatment groups to study the acute effects of WIN 55,212-2 treatment as well the effects of WIN 55,212-2 treatment after an extended washout phase. We could demonstrate that 3 mg/kg WIN 55,212-2 treatment in early adulthood leads to a hypometabolism in several brain regions including the hippocampus, cerebellum, amygdala and midbrain, even after prolonged abstinence. Furthermore, prolonged acute WIN 55,212-2 treatment in 6-months-old mice reduced the glucose metabolism in the hippocampus and midbrain. In addition, Win 55,212-2 treatment during adulthood lead to spatial memory and recognition memory deficits without affecting anxiety behavior. Overall we could demonstrate that treatment with the synthetic CB1/CB2 receptor aganist Win 55,212-2 during adulthood causes persistent memory deficits, especially when mice were treated in early adulthood. Our findings highlight the risks of prolonged WIN 55,212-2 use and provide new insights into the mechanisms underlying the effects of chronic cannabinoid exposure on the brain and behavior. [ABSTRACT FROM AUTHOR]

Background and Purpose: Cannabis legalization has risen in many countries, and its use during pregnancy has increased. The endocannabinoid system is present in the CNS at early stages of embryonic development, and regulates functional brain maturation including areas responsible for respiratory control, data on the influence of external cannabinoids on the development of the respiratory system and possible consequences during postnatal life are limited. Experimental Approach: We evaluated the effects of prenatal exposure to synthetic cannabinoid (WIN 55,212‐2 [WIN], 0.5 mg·kg−1·day−1) on the respiratory control system in neonatal (P0, P6–7 and P12–13) and juvenile (P27–28) male and female rats. Key Results: WIN administration to pregnant rats interfered sex‐specifically with breathing regulation of offspring, promoting a greater sensitivity to CO2 at all ages in males (except P6–7) and in juvenile females. An altered hypoxic chemoreflex was observed in P0 (hyperventilation) and P6–7 (hypoventilation) males, which was absent in females. Along with breathing alterations, brainstem analysis showed an increase in the number of catecholaminergic neurons and cannabinoid receptor type 1 (CB1) and changes in tissue respiration in the early males. A reduction in pulmonary compliance was observed in juvenile male rats. Preexposure to WIN enhanced spontaneous apnoea and reduced the number of serotoninergic (5‐HT) neurons in the raphe magnus nucleus of P0 females. Conclusions and Implications: These data demonstrate that excess stimulation of the endocannabinoid system during gestation has prolonged and sex‐specific consequences for the respiratory control system. [ABSTRACT FROM AUTHOR]

We report here that synthetic cannabinoid WIN 55,212–2 inhibits tumor cell proliferation and induces cell death of oral and pancreatic tumor cells, and the effect is much more pronounced on stem-like/poorly differentiated OSCSCs and MP2 cells when compared to well-differentiated OSCCs, and PL-12 tumor cells. In addition, WIN 55,212-2 decreases cell surface expression of CD44, CD54, MHC class I and PD-L1 on oral and pancreatic tumor cells with the exception of PD-L1 expression on well-differentiated PL-12 pancreatic tumor cells which exhibits an increase in the expression rather than a decrease. Overall, we demonstrate that WIN 55,212-2 has an increased targeting activity against cancer stem cells/poorly differentiated oral and pancreatic tumor cells when compared to well-differentiated tumor cells, and furthermore, such differences in function do not correlate with the levels of CB1 and CB2 receptor expression on tumor cells, suggesting it's function either through post-receptor mediated activation and/or yet-to-be identified novel receptors. Intraperitoneal (IP) delivery of WIN 55-212-2 in humanized BLT mice is found to impart an activating potential for NK cells demonstrating increased NK cell mediated cytotoxicity and secretion of IFN-γ in our preliminary experiments. These results not only suggest a direct targeting of CSCs/poorly differentiated tumors by WIN 55-212-2 but also by indirect targeting of such tumors through the activation and increased functions of NK cells.

Pharmacological synergism is a current strategy for the treatment of pain. However, few studies have been explored to provide evidence of the possible synergism between a non-steroidal anti-inflammatory drug (NSAID) and a cannabinoid agonist, in order to establish which combinations might be effective to manage pain. The aim of this study was to explore the synergism between ibuprofen (IBU) and the synthetic cannabinoid WIN 55,212-2 (WIN) to improve pain relief by analyzing the degree of participation of the CB1 and CB2 cannabinoid receptors in the possible antinociceptive synergism using an experimental model of pain in Wistar rats. First, the effective dose thirty (ED30) of IBU (10, 40, 80, and 160 mg/kg, subcutaneous) and WIN (3, 10, and 30 µg/p, intraplantar) were evaluated in the formalin test. Then, the constant ratio method was used to calculate the doses of IBU and WIN to be administered in combination (COMB) to determine the possible synergism using the isobolographic method. The participation of the CB1 and CB2 receptors was explored in the presence of the antagonists AM281 and AM630, respectively. The combination of these drugs produced a supra-additive response with an interaction index of 0.13. In addition, AM281 and AM630 antagonists reversed the synergistic effect in 45% and 76%, respectively, suggesting that both cannabinoid receptors are involved in this synergism, with peripheral receptors playing a relevant role. In conclusion, the combination of IBU + WIN synergism is mainly mediated by the participation of the CB2 receptor, which can be a good option for the better management of pain relief. [ABSTRACT FROM AUTHOR]

Development of the respiratory system can be affected by the use of drugs during pregnancy, as the prenatal phase is highly sensitive to pharmacological interventions, resulting in long-term consequences. The deleterious effects of external cannabinoids during gestation may be related to negative interference in central nervous system formation, cardiorespiratory system function, and behavioral disorders. Nevertheless, the impact of external cannabinoids on cardiorespiratory network development, chemosensitivity, and its future consequences in adulthood is still unclear. We evaluated the effects of prenatal exposure to a synthetic cannabinoid (WIN 55,212-2, 0.5 mg·kg -1 ·day -1 ) on the cardiorespiratory control and panic-like behavior of male and female rats in adulthood. Exogenous cannabinoid exposure during pregnancy resulted in a sex-dependent difference in breathing control. Specifically, males showed increased chemosensitivity to CO 2 and O 2 , whereas females exhibited decreased sensitivity. Altered cardiovascular control was evident, with prenatally treated males and females being more susceptible to hypertension and tachycardia under adverse environmental conditions. Moreover, WIN-treated males exhibited higher fragmentation of sleep episodes, whereas females displayed anxiolytic and panicolytic behavioral responses to CO 2 . However, no changes were observed in the mechanical component of the respiratory system, and there were no neuroanatomical alterations, such as changes in the expression of CB 1 receptors in the brainstem or in the quantification of catecholaminergic and serotonergic neurons. These findings highlight that external interference in cannabinoid signaling during fetal development causes sex-specific, long-lasting effects for the cardiorespiratory system and behavioral responses in adulthood. NEW & NOTEWORTHY The surge in recreational cannabis use and cannabinoid-based medication prescription among pregnant women has been notable in recent years, fueled by the misconception that natural products are inherently safe. Significant gaps persist regarding the potential risks of maternal consumption of cannabinoids and the long-term effects on the cardiorespiratory system of their offspring, which may be determined by sex. Accordingly, this research aims to diminish this lack of information and raise a note of caution.

Drugs of abuse including cannabis and inhalants impair risk/reward decision making. Cannabis use is often concurrent with inhalant intoxication; yet, preclinical studies investigating the role of endocannabinoids in inhalant misuse are limited. To address this gap in the literature, we used the well-validated probabilistic discounting task to assess risk/reward decision making in rodents following combinations of toluene vapor (a common inhalant) and manipulations of cannabinoid receptor type 1 (CB1R) signaling. As reported previously, acute exposure to toluene vapor disrupted behavioral flexibility during probabilistic discounting. Systemic administration of the CB1R inverse agonist AM281 did not prevent toluene-induced alterations in risky choices, but did independently reduce win-stay behavior, increase choice latency, and increase omissions. Toluene-induced deficits in probabilistic discounting are thought to involve impaired medial prefrontal cortex (mPFC) activity. As we previously reported that some of toluene's inhibitory effects on glutamatergic signaling in the mPFC are endocannabinoid-dependent, we tested the hypothesis that mPFC CB1R activity mediates toluene-induced deficits in discounting. However, bilateral injection of the CB1R inverse agonist AM251 prior to toluene vapor exposure had no effect on toluene-induced changes in risk behavior. In a final set of experiments, we injected the CB1R inverse agonist AM251 (5 and 50 ng), the CB1R agonist WIN55,212–2 (50 ng and 500 ng), or vehicle into the mPFC prior to testing. While mPFC CB1R stimulation did not affect any of the measures tested, the CB1R inverse agonist caused a dose-dependent reduction in win-stay behavior without altering any other measures. Together, these studies indicate that toluene-induced deficits in probabilistic discounting are largely distinct from CB1R-dependent effects that include decreased effectiveness of positive reinforcement (mPFC CB1Rs), decision making speed, and task engagement (non-mPFC CB1Rs). [ABSTRACT FROM AUTHOR]

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which can infect several organs, especially impacting respiratory capacity. Among the extrapulmonary manifestations of COVID-19 is myocardial injury, which is associated with a high risk of mortality. Myocardial injury, caused directly or indirectly by SARS-CoV-2 infection, can be triggered by inflammatory processes that lead to damage to the heart tissue. Since one of the hallmarks of severe COVID-19 is the “cytokine storm”, strategies to control inflammation caused by SARS-CoV-2 infection have been considered. Cannabinoids are known to have anti-inflammatory properties by negatively modulating the release of pro-inflammatory cytokines. Herein, we investigated the effects of the cannabinoid agonist WIN 55,212-2 (WIN) in human iPSC-derived cardiomyocytes (hiPSC-CMs) infected with SARS-CoV-2. WIN did not modify angiotensin-converting enzyme II protein levels, nor reduced viral infection and replication in hiPSC-CMs. On the other hand, WIN reduced the levels of interleukins six, eight, 18 and tumor necrosis factor-alpha (TNF-α) released by infected cells, and attenuated cytotoxic damage measured by the release of lactate dehydrogenase (LDH). Our findings suggest that cannabinoids should be further explored as a complementary therapeutic tool for reducing inflammation in COVID-19 patients.

Rationale: Nucleus cuneiformis (NC), a reticular nucleus of the midbrain, is a part of the descending pain modulatory system and therefore has an important role in pain perception. Objectives: Considering the abundance of GABAA and cannabinoid receptors in the NC and also the bidirectional roles for GABA in controlling nociception, the present study examined the effects of bilateral intra-NC microinjection of different doses of the GABAA receptor agonist, muscimol, and the GABAA receptor antagonist, bicuculline, on pain modulation using formalin test. We also assessed interaction between canabinergic and GABAergic systems in the NC during this test. Methods: Rats were exposed to intra-NC microinjection of bicuculline (50,100, and 200 ng/side) or muscimol (60, 120, and 240 ng/side) and then subjected to the formalin test. In another set of experiments, the effects of muscimol (60 ng/side) or bicuculline (50 ng/side) administration 5 min before a cannabinoid receptor agonist WIN 55,212-2 (5, 10, and 20 μg/side) microinjection into NC on the formalin test were evaluated. Results: Microinjection of bicuculline and muscimol into the NC decreased and increased pain responses, respectively, in a dose-dependent manner during both phases of the test. Microinjection of WIN 55,212-2 into the NC significantly reduced pain responses in a dose-dependent manner. Microinjection of bicuculline or muscimol in combination with WIN 55,212-2 into the NC respectively potentiated and attenuated WIN 55,212-2–induced antinociception in the formalin test. Conclusions: This study shows that GABA in the NC is involved in pain modulation and suggests the existence of a GABAA-mediated inhibitory system in the NC on pain control. Furthermore, it seems that the antinociceptive effect of WIN 55,212-2 in the formalin test is mediated partly by the activity of local GABAA receptors in the NC. [ABSTRACT FROM AUTHOR]

The minimum alveolar concentration MAC of isoflurane was measured in rats chronically treated with WIN 55,212-2. Methods: The MAC of isoflurane was determined in 24 male rats from expiratory samples at time of tail clamping under the following conditions: without treatment MAC(ISO), in rats treated for 21 days with WIN 55,212-2 MAC(ISO + WIN55), and in rats 8 days after stopping treatment with WIN 55,212-2 (MACISO + WIN55 + 8D). Results: The MAC(ISO) was 1.32 ± 0.06. In the MAC(ISO + WIN55) group, the MAC increased to 1.69 ± 0.09 (28%, p-value ≤ (0.0001). Eight days after stopping treatment with WIN55, the MAC did not decrease significantly, 1.67 ± 0.07 (26%, p-value ≤ 0.0001). Conclusions: The administration of WIN 55,212-2 for 21 days increases the MAC of isoflurane in rats. This effect does not disappear 8 days after discontinuation of treatment with the synthetic cannabinoid.

Introduction: For centuries, cannabinoids are known to be effective in pain relief. Itch is an unpleasant sensation that provokes a desire to scratch. Since itch and pain are two sensations sharing a lot in common, we aimed to investigate whether the cannabinoid agonist WIN 55,212-2 reduces serotonin-induced scratching behavior and also observe whether modulation of Nitric Oxide (NO) production mediates the antipruritic effect of WIN 55,212-2. Methods: Scratching behavior is induced by intradermal injection of serotonin (50 µg/50 µL/mouse) to BALB/c mice. The cannabinoid agonist WIN 55,212-2 (1, 3, 10 mg/kg, IP) was given 30 min before serotonin injection. To observe the effect of NO modulation on the antipruritic effect of cannabinoids, the endothelial nitric oxide synthase (NOS) inhibitor L-NAME (3 mg/kg, IP), the neuronal NOS inhibitor 7-nitroindazole (3 mg/kg, IP), and the NO precursor L-arginine (100 mg/kg, IP) were administered together with WIN 55,212-2. Results: WIN 55,212-2 reduced serotonin-induced scratches at higher doses (3, 10 mg/kg; P<0.0001). The endothelial NOS inhibitor L-NAME, the neuronal NOS inhibitor 7-nitroindazole, and the nitric oxide precursor L-arginine did not influence the antipruritic action of WIN 55,212-2. When NO modulators were used alone, only the neuronal NOS inhibitor 7-nitroindazole attenuated serotonin-induced scratches (P<0.0001). Conclusion: Our findings indicate that exogenous cannabinoids may attenuate serotonininduced scratches and NO does not mediate the antipruritic effect of WIN 55,212-2. On the other hand, neuronal NOS inhibition may play a role in the production of serotonin-induced scratches. [ABSTRACT FROM AUTHOR]

Delayed neurologic sequelae (DNS) are among the most serious complications of carbon monoxide (CO) poisoning caused partly by elevated neuroinflammation. WIN 55,212-2, a non-selective agonist of cannabinoid receptors, has been demonstrated to have anti-inflammatory properties in various brain disorders. The anti-inflammatory action of WIN 55,212-2 is potentially associated with driving microglial M2 polarization. ST2 signaling is important in regulating inflammatory responses and microglial polarization. Therefore, we aimed to investigate the neuroprotective effect of WIN 55,212-2 on DNS after CO poisoning and elucidate its relationship with ST2-mediated microglial M2 polarization. The behavioral tests showed that treatment with WIN 55,212-2 significantly ameliorates the cognitive impairment induced by CO poisoning. This behavioral improvement was accompanied by reduced neuron loss, decreased production of pro-inflammatory cytokines, and a limited number of microglia in the hippocampus. Moreover, WIN 55,212-2 elevated the protein expression of IL-33 (the ligand of ST2) and ST2, increased the ratio of CD206-positive (M2 phenotype) and ST2-positive microglia, and augmented production of M2 microglia-associated cytokines in the hippocampus of CO-exposed rats. Furthermore, we observed that the WIN 55,212-2-mediated increases in ST2 protein expression, CD206-positive and ST2-positive microglia, and microglia-associated cytokines were blocked by the cannabinoid receptor 2 (CB2R) antagonist AM630 but not by the cannabinoid receptor 1 (CB1R) antagonist AM251. In contrast, the WIN 55,212-2-induced upregulation of the IL-33 protein expression was inhibited by AM251 but not by AM630. Altogether, these findings reveal cannabinoid receptors as promising therapeutic agents for CO poisoning and identify ST2 signaling-related microglial M2 polarization as a new mechanism of cannabinoid-induced neuroprotection. [ABSTRACT FROM AUTHOR]

Background: Cannabinoids (the active components of Cannabis sativa) and their derivatives have received considerable interest due to reports that they can affect the tumor growth, migration, and metastasis. Previous studies showed that the cannabinoid agonist WIN 55,212-2 (WIN) was associated with gastric cancer (GC) metastasis, but the mechanisms were unknown. Methods: The effects of WIN on GC cell migration and invasion were analyzed by the wound-healing assay and Transwell assay. Quantitative real-time PCR and Western blot were used to evaluate changes in expression of COX-2 and EMT associated markers in SGC7901 and AGS cells. Results: WIN inhibited cell migration, invasion, and epithelial to mesenchymal transition (EMT) in GC. WIN treatment resulted in the downregulation of cyclooxygenase-2 (COX-2) expression and decreased the phosphorylation of AKT, and inhibited EMT in SGC7901 cells. Decreased expression of COX-2 and vimentin, and increased expression of E-cadherin, which was induced by WIN, were normalized by overexpression of AKT, suggesting that AKT mediated, at least partially, the WIN suppressed EMT of GC cells. Conclusion: WIN can inhibit the EMT of GC cells through the downregulation of COX-2.

The endocannabinoid (eCB) signaling system has been functionally implicated in many brain regions. Our understanding of the role of cannabinoid receptor type 1 (CB1) in olfactory processing remains limited. Cannabinoid signaling is involved in regulating glomerular activity in the main olfactory bulb (MOB). However, the cannabinoid-related circuitry of inputs to mitral cells in the MOB has not been fully determined. Using anatomical and functional approaches we have explored this question. CB1 was present in periglomerular processes of a GAD65-positive subpopulation of interneurons but not in mitral cells. We detected eCBs in the mouse MOB as well as the expression of CB1 and other genes associated with cannabinoid signaling in the MOB. Patch-clamp electrophysiology demonstrated that CB1 agonists activated mitral cells and evoked an inward current, while CB1 antagonists reduced firing and evoked an outward current. CB1 effects on mitral cells were absent in subglomerular slices in which the olfactory nerve layer and glomerular layer were removed, suggesting the glomerular layer as the site of CB1 action. We previously observed that GABAergic periglomerular cells show the inverse response pattern to CB1 activation compared with mitral cells, suggesting that CB1 indirectly regulates mitral cell activity as a result of cellular activation of glomerular GABAergic processes. This hypothesis was supported by the finding that cannabinoids modulated synaptic transmission to mitral cells. We conclude that CB1 directly regulates GABAergic processes in the glomerular layer to control GABA release and, in turn, regulates mitral cell activity with potential effects on olfactory threshold and behavior. [ABSTRACT FROM AUTHOR]

Severe and poorly treated pain often accompanies breast cancer. Thus, novel mechanisms involved in breast cancer-induced pain should be investigated. Then, it is necessary to characterize animal models that are reliable with the symptoms and progression of the disease as observed in humans. Explaining cancer-induced nociception in a murine model of breast carcinoma was the aim of this study. 4T1 (104) lineage cells were inoculated in the right fourth mammary fat pad of female BALB/c mice; after this, mechanical and cold allodynia, or mouse grimace scale (MGS) were observed for 30 days. To determine the presence of bone metastasis, we performed the metastatic clonogenic test and measure calcium serum levels. At 20 days after tumor induction, the antinociceptive effect of analgesics used to relieve pain in cancer patients (acetaminophen, naproxen, codeine or morphine) or a cannabinoid agonist (WIN 55,212-2) was tested. Mice inoculated with 4T1 cells developed mechanical and cold allodynia and increased MGS. Bone metastasis was confirmed using the clonogenic assay, and hypercalcemia was observed 20 days after cells inoculation. All analgesic drugs reduced the mechanical and cold allodynia, while the MGS was decreased only by the administration of naproxen, codeine, or morphine. Also, WIN 55,212-2 improved all nociceptive measures. This pain model could be a reliable form to observe the mechanisms of breast cancer-induced pain or to observe the efficacy of novel analgesic compounds. [ABSTRACT FROM AUTHOR]

The antinociceptive effects of cannabinoids and opioids have been known for centuries. Serotonin and its receptors are also known to play important roles in nociception. However, the contribution of spinal 5-HT5A receptors in antinociceptive effects of cannabinoids and opioids has not been studied. We conducted this study to clarify spinal mechanisms of the actions of the antinociceptive effects of cannabinoids and opioids. Hot plate and tail flick tests were used to assess the antinociceptive activity in Balb/c mice. WIN 55,212-2, a nonselective CB1 and CB2 agonist, and morphine exerted significant antinociceptive effects at 1, 3, and 10 mg/kg doses administered intraperitoneally in both hot plate and tail flick tests. The selective 5-HT5A receptor antagonist SB-699551 (10 nmol/mouse) was administered intrathecally 10 min before the agonists. SB-699551 significantly reduced the antinociceptive effect of both WIN 55,212-2 and morphine. In the rotarod test, WIN 55,212-2 disrupted the motor coordination at a dose of 10 mg/kg, while morphine did not affect this function at any dose. Our findings show that spinal 5-HT5A receptors are involved in the antinociceptive effects of WIN 55,212-2 and morphine. [ABSTRACT FROM AUTHOR]

Objective Although drugs targeting the cannabinoid system (e.g., CB1 receptor agonists) display anticonvulsant efficacy in adult animal models of seizures/epilepsy, they remain unexplored in developing animal models. However, cannabinoid system functions emerge early in development, providing a rationale for targeting this system in neonates. We examined the therapeutic potential of drugs targeting the cannabinoid system in three seizure models in developing rats. Methods Postnatal day (P) 10, Sprague-Dawley rat pups were challenged with the chemoconvulsant methyl-6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate ( DMCM) or pentylenetetrazole ( PTZ), after treatment with either CB1/2 mixed agonist ( WIN 55,212-2), CB1 agonist ( arachidonyl-2′-chloroethylamide [ACEA]), CB2 agonist ( HU-308), CB1 antagonist ( AM-251), CB2 antagonist ( AM-630), fatty acid amide hydrolase inhibitor ( URB-597), or G protein-coupled receptor 55 agonist (O-1602). P20 Sprague-Dawley pups were challenged with DMCM after treatment with WIN, ACEA, or URB. Finally, after pretreatment with WIN, P10 Sprague-Dawley rats were challenged against acute hypoxia-induced seizures. Results The mixed CB1/2 agonist and the CB1-specific agonist, but no other drugs, displayed anticonvulsant effects against clonic seizures in the DMCM model. By contrast, both CB1 and CB2 antagonism increased seizure severity. Similarly, we found that the CB1/2 agonist displayed antiseizure efficacy against acute hypoxia-induced seizures (automatisms, clonic and tonic-clonic seizures) and tonic-clonic seizures evoked by PTZ. Anticonvulsant effects were seen in P10 animals but not P20 animals. Significance Early life seizures represent a significant cause of morbidity, with 30-40% of infants and children with epilepsy failing to achieve seizure remission with current pharmacotherapy. Identification of new therapies for neonatal/infantile epilepsy syndromes is thus of high priority. These data indicate that the anticonvulsant action of the CB system is specific to CB1 receptor activation during early development and provide justification for further examination of CB1 receptor agonists as novel antiepileptic drugs targeting epilepsy in infants and children. [ABSTRACT FROM AUTHOR]

BackgroundFor centuries, cannabinoids have been known to be effective in pain states. Itch and pain are two sensations sharing a lot in common.ObjectiveThe goal of this research was to observe whether the cannabinoid agonist WIN 55,212-2 reduces serotonin-induced scratching behaviour and whether neurotoxic destruction of descending serotonergic and noradrenergic pathways mediate the antipruritic effect of WIN 55,212-2.Material and methodsScratching behaviour was induced by intradermal injection of serotonin (50 µg/50 µl/mouse) to Balb/c mice. The neurotoxins 5,7-dihydroxytryptamine (5,7-DHT, 50 μg/mouse) and 6-hydroxydopamine (6-OHDA, 20 μg/mouse) are applied intrathecally to deplete serotonin and noradrenaline in the spinal cord. WIN 55,212-2 (1, 3, 10 mg/kg, i.p.) dose-dependently attenuated serotonin-induced scratches. Neurotoxic destruction of neither the serotonergic nor the noradrenergic systems by 5,7-DHT and 6-OHDA, respectively, had any effect on the antipruritic action of WIN 55,212-2.ConclusionOur findings indicate that cannabinoids dose-dependently reduce serotonin-induced scratching behaviour and neurotoxic destruction of descending inhibitory pathways does not mediate this antipruritic effect. [ABSTRACT FROM AUTHOR]

Background: Cannabinoids (the active components of Cannabis sativa) and their derivatives have received considerable interest due to reports that they can affect the tumor growth, migration, and metastasis. Previous studies showed that the cannabinoid agonist WIN 55,212-2 (WIN) was associated with gastric cancer (GC) metastasis, but the mechanisms were unknown. Methods: The effects of WIN on GC cell migration and invasion were analyzed by the wound-healing assay and Transwell assay. Quantitative real-time PCR and Western blot were used to evaluate changes in expression of COX-2 and EMT associated markers in SGC7901 and AGS cells. Results: WIN inhibited cell migration, invasion, and epithelial to mesenchymal transition (EMT) in GC. WIN treatment resulted in the downregulation of cyclooxygenase-2 (COX-2) expression and decreased the phosphorylation of AKT, and inhibited EMT in SGC7901 cells. Decreased expression of COX-2 and vimentin, and increased expression of E-cadherin, which was induced by WIN, were normalized by overexpression of AKT, suggesting that AKT mediated, at least partially, the WIN suppressed EMT of GC cells. Conclusion: WIN can inhibit the EMT of GC cells through the downregulation of COX-2. [ABSTRACT FROM AUTHOR]

Objective(s): Diabetic neuropathy (DN) is a common complication of diabetes that leads to allodynia, impaired nerve conduction, and progressive sensory loss. The aim of this study was to observe the effect of a high-affinity cannabinoid receptors agonist, WIN 55,212-2, on thermal hyperalgesia, nerve conduction velocity and sciatic nerve histopathology in diabetic rats. Materials and Methods: Diabetes was induced in rats using a single dose of streptozotocin (45 mg/kg IP). Results: Intrathecal (IT) administration of WIN55, 212-2 (1, 10, 100 μg/10 μl, IT), produced antinociceptive effects in the hot plate test and also improved nerve conduction velocity (100 μg/10 μl, IT) and sciatic nerve histology. Conclusion: These data show that cannabinoids have potent antinociceptive effects through direct actions in the spinal dorsal horn of nociceptive pathway. This suggests that intrathecally administered cannabinoids may offer hopeful strategies for the treatment of diabetic neuropathic pain. [ABSTRACT FROM AUTHOR]

Recent studies demonstrate a differential trajectory for cannabinoid receptor expression in cortical and sub-cortical brain areas across postnatal development. In the present study, we sought to investigate whether chronic systemic exposure to a synthetic cannabinoid receptor agonist causes morphological changes in the structure of dendrites and dendritic spines in adolescent and adult pyramidal neurons in the medial prefrontal cortex (mPFC) and medium spiny neurons (MSN) in the nucleus accumbens (Acb). Following systemic administration of WIN 55,212-2 in adolescent (PN 37-40) and adult (P55-60) male rats, the neuronal architecture of pyramidal neurons and MSN was assessed using Golgi-Cox staining. While no structural changes were observed in WIN 55,212-2-treated adolescent subjects compared to control, exposure to WIN 55,212-2 significantly increased dendritic length, spine density and the number of dendritic branches in pyramidal neurons in the mPFC of adult subjects when compared to control and adolescent subjects. In the Acb, WIN 55,212-2 exposure significantly decreased dendritic length and number of branches in adult rat subjects while no changes were observed in the adolescent groups. In contrast, spine density was significantly decreased in both the adult and adolescent groups in the Acb. To determine whether regional developmental morphological changes translated into behavioral differences, WIN 55,212-2-induced aversion was evaluated in both groups using a conditioned place preference paradigm. In adult rats, WIN 55,212-2 administration readily induced conditioned place aversion as previously described. In contrast, adolescent rats did not exhibit aversion following WIN 55,212-2 exposure in the behavioral paradigm. The present results show that synthetic cannabinoid administration differentially impacts cortical and sub-cortical neuronal morphology in adult compared to adolescent subjects. Such differences may underlie the disparate development effects of cannabinoids on behavior. [ABSTRACT FROM AUTHOR]

Summary The influence of WIN 55,212-2 mesylate (WIN) on the anticonvulsant activity and acute neurotoxic potential of clobazam (CLB) and lacosamide (LCM) was studied in the maximal electroshock-induced seizure (MES) model and chimney test in mice. Results indicate that WIN administered intraperitoneally, at doses of 2.5 and 5 mg/kg significantly enhanced the anticonvulsant action of CLB in the MES test by reducing its median effective dose (ED 50 ) from 20.80 mg/kg to 12.05 mg/kg ( P < 0.05), and 8.22 mg/kg ( P < 0.001), respectively. In contrast, WIN (1.25 mg/kg) did not significantly potentiate the anticonvulsant activity of CLB against MES-induced seizures. Similarly, WIN at doses of 1.25, 2.5 and 5 mg/kg had no significant impact on the anticonvulsant action of LCM in the MES test. On the other hand, WIN (5 mg/kg) had no impact on the acute neurotoxic effects of CLB and LCM in the chimney test and the median toxic doses (TD 50 ) for CLB and LCM were almost unchanged. Thus, WIN (5 mg/kg) elevated the protective index values for CLB (from 1.41 to 3.07) and LCM (from 3.60 to 4.91). In conclusion, WIN potentiates suppression of tonic–clonic seizures produced by CLB in the mouse MES model, without affecting acute neurotoxic adverse effects of CLB in the chimney test in mice, which is favorable from a preclinical point of view. [ABSTRACT FROM AUTHOR]

Cannabinoids exert various biological effects that are either receptor-mediated or independent of receptor signaling. Mitochondrial effects of cannabinoids were interpreted either as non-receptor-mediated alteration of mitochondrial membranes, or as indirect consequences of activation of plasma membrane type 1 cannabinoid receptors (CB 1 ). Recently, CB 1 receptors were confirmed to be localized to the membranes of neuronal mitochondria, where their activation directly regulates respiration and energy production. Here, we performed in-depth analysis of cannabinoid-induced changes of mitochondrial respiration using both an antagonist/inverse agonist of CB 1 receptors, AM251 and the cannabinoid receptor agonists, Δ 9 -tetrahydrocannabinol (THC), cannabidiol, anandamide, and WIN 55,212-2. Relationships were determined between cannabinoid concentration and respiratory rate driven by substrates of complex I, II or IV in pig brain mitochondria. Either full or partial inhibition of respiratory rate was found for the tested drugs, with an IC 50 in the micromolar range, which verified the significant role of non-receptor-mediated mechanism in inhibiting mitochondrial respiration. Effect of stepwise application of THC and AM251 evidenced protective role of AM251 and corroborated the participation of CB 1 receptor activation in the inhibition of mitochondrial respiration. We proposed a model, which includes both receptor- and non-receptor-mediated mechanisms of cannabinoid action on mitochondrial respiration. This model explains both the inhibitory effect of cannabinoids and the protective effect of the CB 1 receptor inverse agonist. [ABSTRACT FROM AUTHOR]

• METH regimen impaired social interaction and the acquisition, consolidation, retrieval, and reconsolidation of NOR. • Rimonabant improved METH-induced deficits of the acquisition, consolidation, and retrieval, but not reconsolidation, of NOR. • Rimonabant improved METH-induced impairment of social behavior. • WIN administration did not affect deficits in memory and social behavior induced by METH. Methamphetamine (METH) has been reported to induce social and recognition memory impairment. Evidence suggests that the cannabinoid system has an important modulatory role in cognitive processing and social interaction. Nonetheless, no previous study has investigated the probable role of the cannabinoids system on METH-induced deficits of novel object recognition (NOR) memory and social interaction. Adult male rats were given a neurotoxic METH regimen (four injections of 6 mg/kg, s.c, at 2 h intervals). One week later, they were examined for either NOR or social interaction in different groups. The cannabinoid type 1 receptor (CB 1 R) antagonist rimonabant (1 or 3 mg/kg, i.p.) improved METH-induced impairment of the acquisition, consolidation, and retrieval, but not reconsolidation, of NOR and also METH-induced impairment of social behavior. Administration of the CB 1 R agonist WIN 55,212–2 (WIN; 3 or 5 mg/kg, i.p.) did not affect memory deficits or social behavior impairment induced by METH. Our findings may indicate that METH neurotoxicity impairs social and recognition memory. On the other hand, the CB 1 R antagonist rimonabant, but not the CB 1 R agonist WIN, prevented these negative effects of METH neurotoxicity. Thus, it seems that the CB 1 R can be targeted to prevent the adverse effects of METH on cognition and social behavior, at least at experimental levels. [ABSTRACT FROM AUTHOR]

Cannabis is one of the most banned drugs in the world. Cannabinoid-induced dependence or withdrawal signs are indicated by the result of complex molecular mechanisms including upstream protein kinases (PKs), such as an extracellular signal regulated kinase1/2 (ERK1/2) and downstream glycogen synthase kinase-3β (GSK-3β), which lead to neuronal plasticity. In this study, we examined the protective effect of lithium (Li) as a potent ERK1/2 and GSK-3β modulator to prevent the development of dependence on cannabinoids. For this purpose, rats were treated twice daily with increasing doses of WIN 55,212-2 (WIN, 2-8 mg/kg, intraperitoneally (i.p.), for five consecutive days. AM251 (AM, 2 mg/kg), a cannabinoid antagonist, was injected i.p to induce manifestations of abstinence in rat dependency on WIN, and the subsequent withdrawal signs were recorded. To evaluate the preventive effect of Li, the rats were pre-treated with Li (10 mg/kg, i.p.) twice daily, 30 minutes before every injection of WIN. SL327, as an ERK1/2 inhibitor, was also injected (SL, 50 mg/kg, i.p.) 30 minutes before the last doses of WIN in separate groups. The p-ERK1/2, total ERK1/2, p-GSK-3β and total GSK-3β expressions were determined with Western blot method after 60 minutes, prior to the Li, WIN or AM injections. Li and SL pre-treatment attenuated the global withdrawal signs in regarding their modulation effect on the up-regulation of p-ERK1/2 cascade enhanced by AM injection. Furthermore, the p-GSK-3β expression was up-regulated with SL and Li pre- treatment against AM injection, without alteration on the total contents of ERK1/2 and GSK-3β level. Therefore, p-ERK1/2 and p-GSK-3β pathways are involved in the cannabinoid-induced dependence. However, no crosstalk was indicated between these two pathways. In conclusion, Li neuroprotectionwith regard to cannabinoid abstinence may occur through the regulation of the p-ERK1/2 cascade inconsequent of p-GSK-3β signaling pathways in rats. [ABSTRACT FROM AUTHOR]

The aim of this study was to characterize the influence of WIN 55,212-2 (WIN-a non-selective cannabinoid CB and CB receptor agonist) on the anticonvulsant effects of various classical antiepileptic drugs (clobazam, clonazepam, phenobarbital and valproate) in the mouse 6 Hz-induced psychomotor seizure model. Limbic (psychomotor) seizure activity was evoked in albino Swiss mice by a current (32 mA, 6 Hz, 3 s stimulus duration) delivered via ocular electrodes. Drug-related adverse effects were ascertained by use of the chimney test (evaluating motor performance), step-through passive avoidance task (assessing learning) and grip-strength test (evaluating skeletal muscular strength). Total brain concentrations of antiepileptic drugs were measured by fluorescence polarization immunoassay to ascertain any pharmacokinetic contribution to the observed antiseizure effect. Results indicate that WIN (5 mg/kg, administered intraperitoneally) significantly enhanced the anticonvulsant action of clonazepam ( P < 0.001), phenobarbital ( P < 0.05) and valproate ( P < 0.05), but not that of clobazam in the mouse 6 Hz model. Moreover, WIN (2.5 mg/kg) significantly potentiated the anticonvulsant action of clonazepam ( P < 0.01), but not that of clobazam, phenobarbital or valproate in the 6 Hz test in mice. None of the investigated combinations of WIN with antiepileptic drugs was associated with any concurrent adverse effects with regard to motor performance, learning or muscular strength. Pharmacokinetic experiments revealed that WIN had no impact on total brain concentrations of antiepileptic drugs in mice. These preclinical data would suggest that WIN in combination with clonazepam, phenobarbital and valproate is associated with beneficial anticonvulsant pharmacodynamic interactions in the mouse 6 Hz-induced psychomotor seizure test. [ABSTRACT FROM AUTHOR]

Considering the existence of cross-tolerance between clonidine and morphine besides the same interaction between morphine and WIN 55,212-2 persuaded us to verify this fact between WIN 55,212-2 and clonidine in guinea pig ileum, which is a well-known model to examine the mode of action of cannabinoids and α2-adenoceptor agonists, The rectangular pulses were passed to the 0.5 g stretched ileum segments that were fixed in 20-ml organ bath. PowerLab system and Graphpad Prism were applied to record twitches and analyse the data. Electrically evoked contractions were dose-dependently inhibited by WIN 55,212-2 and clonidine ( p D 2= 8.56 ± 0.41 and 7.65 ± 0.15, respectively)., Tolerance to this effect could be induced by 4-h incubation with WIN 55,212-2 (3 × IC50) ( pD2 = 6.36 ± 0.26, degree of tolerance: 159.32) ( P < 0.01) but not with clonidine (2 × IC50 and 4 × IC50) for different time courses. Dose-response curve for inhibitory action of WIN 55,212-2 was shifted to the right after 4-h incubation with clonidine (3 × 10−10 m) comparing to the untreated tissues ( pD2 = 5.26 ± 0.69, degree of tolerance: 2000) ( P < 0.001). This observation provides the evidence for the cannabinoid-noradrenergic systems interaction in the enteric nervous system as a simplified representative for central nervous system. [ABSTRACT FROM AUTHOR]

Background: We have previously reported the antineoplastic effects of a cannabinoid agonist in gastric cancer cells. Our aim was to evaluate this in a murine xenograft model. Methods: Animal models were created after injecting AGS gastric cancer cells subcutaneously into the flank of male BALB/c-nude mice. A cannabinoid agonist, WIN 55,212-2 (7 mg/kg body weight) or vehicle was injected around the tumor subcutaneously every 24 h for 14 days. Tumors were explanted for analysis. Results: Tumor volume decreased by 30% in the WIN 55,212-2-treated group compared to the group treated with vehicle (p < 0.05). Apoptotic cells were found more commonly in the WIN 55,212-2 treatment group than in the control on immunohistochemistry. Compared to the control, WIN 55,212-2 treatment significantly increased caspase-3 cleavage and decreased MMP-2, MMP-7 and MMP-9 protein levels significantly (all p < 0.05). VEGF-A protein level was not different between the 2 groups. Conclusion: WIN 55,212-2 has antineoplastic effect on the gastric cancers in in vivo model. © 2013 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Cannabinoid CB1 receptors have been implicated in the antinociceptive effect of paracetamol. In the current study, we examined whether blockade of CB1 receptors prevent the analgesic activity of dipyrone, in a similar way to paracetamol. Hot-plate and tail-flick tests were used to assess the antinociceptive activity in mice. Dipyrone and WIN 55,212-2, a cannabinoid agonist, exerted significant antinociceptive effects in both hot-plate and tail flick tests. The CB1 receptor antagonist, AM-251 (3 mg/kg), at a dose which had no effect when used alone, did not alter the antinociceptive effect of dipyrone, whereas completely prevented the antinociceptive activity of WIN 55,212-2 in both thermal antinociceptive tests. Our findings suggest that, unlike paracetamol, cannabinoid CB1 receptors do not participate in the antinociceptive action of dipyrone when acute pain tests used. [ABSTRACT FROM AUTHOR]

Highlights: [•] Drug study on fear memory and cannabinoids in prefrontal cortex and amygdala. [•] Cannabinoids reduce fear learning in amygdala and prefrontal cortex. [•] Cannabinoid antagonists impair fear extinction in the prefrontal cortex. [ABSTRACT FROM AUTHOR]

Abstract: The cannabinoid receptor agonist, WIN 55,212-2, increases extracellular norepinephrine levels in the rat frontal cortex under basal conditions, likely via desensitization of inhibitory α2-adrenergic receptors located on norepinephrine terminals. Here, the effect of WIN 55,212-2 on stress-induced norepinephrine release was assessed in the medial prefrontal cortex (mPFC), in adult male Sprague–Dawley rats using in vivo microdialysis. Systemic administration of WIN 55,212-2 30min prior to stressor exposure prevented stress-induced cortical norepinephrine release induced by a single exposure to swim when compared to vehicle. To further probe cortical cannabinoid–adrenergic interactions, postsynaptic α2-adrenergic receptor (AR)-mediated responses were assessed in mPFC pyramidal neurons using electrophysiological analysis in an in vitro cortical slice preparation. We confirm prior studies showing that clonidine increases cortical pyramidal cell excitability and that this was unaffected by exposure to acute stress. WIN 55,212-2, via bath application, blocked postsynaptic α2-AR mediated responses in cortical neurons irrespective of exposure to stress. Interestingly, stress exposure prevented the desensitization of α2-AR mediated responses produced by a history of cannabinoid exposure. Together, these data indicate the stress-dependent nature of cannabinoid interactions via both pre- and postsynaptic ARs. In summary, microdialysis data indicate that cannabinoids restrain stress-induced cortical NE efflux. Electrophysiology data indicate that cannabinoids also restrain cortical cell excitability under basal conditions; however, stress interferes with these CB1–α2 AR interactions, potentially contributing to over-activation of pyramidal neurons in mPFC. Overall, cannabinoids are protective of the NE system and cortical excitability but stress can derail this protective effect, potentially contributing to stress-related psychopathology. These data add to the growing evidence of complex, stress-dependent modulation of monoaminergic systems by cannabinoids and support the potential use of cannabinoids in the treatment of stress-induced noradrenergic dysfunction. [Copyright &y& Elsevier]