Characterization of Cancer-Induced Nociception in a Murine Model of Breast Carcinoma.

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.

Neumomediastino y necrosis cutánea en asociación a dermatomiositis: presentación de un caso clínico y revisión de la literatura / Pneumomediastinum and cutaneous necrosis in dermatomyositis: Report of one case

We report a 37 years old male with a dermatomyositis treated with oral cyclophosphamide. He was admitted to the hospital due to a zone of skin necrosis with purulent exudate, located in the second left toe. A complete blood count showed a leukocyte count of 2,600 cells/mm³. A Chest CAT scan showed a pneumomediastinum with emphysema of adjacent soft tissue. Cyclophosphamide was discontinued and leukocyte count improved. The affected toe was amputated and a chest CAT scan showed a partial resolution of the pneumomediastinum. We discuss and review the pathogenesis, clinical presentation and management of pneumomediastinum and cutaneous necrosis in association with dermatomyositis.

A current overview of cannabinoids and glucocorticoids in facilitating extinction of aversive memories: potential extinction enhancers.

Emotional learning is extremely important for the survival of an individual. However, once acquired, emotional associations are not always expressed. The regulation of emotional responses under different environmental conditions is essential for mental health. Indeed, pathologic feelings of fear and anxiety are defining features of many serious psychiatric illness, including post-traumatic stress disorder (PTSD) and specific phobias. The simplest form of regulation of emotional responses is extinction, in which the conditioned response to a stimulus decreases when reinforcement (stimulus) is omitted. In addition to modulating basal anxiety states, recent studies suggest an important role for the endocannabinoid (eCB) and glucocorticoid systems in the modulation of emotional states and extinction of aversive memories in animals. The purpose of this review is to briefly outline the animal models of fear extinction and to describe how these have been used to examine the potential of extinction enhancing agents which specifically alter the eCB and glucocorticoid systems. Pharmacological manipulations of these systems by agents such as cannabinoid or glucocorticoid agonists can enhance the extinction process and avoid the retention of memories which have the potential to trigger trauma. A better understanding of these findings through animal models highlights the possibilities of using combined extinction enhancing agents in exposure-based psychotherapies for anxiety disorders related to inappropriate retention of aversive memories. This article is part of a special issue entitled 'Cognitive Enhancers'.

Cannabinoid-induced conditioned place preference in the spontaneously hypertensive rat-an animal model of attention deficit hyperactivity disorder.

RATIONALE: Cannabis preparations are the most widely consumed illicit drugs, and their use typically begins in adolescence. The prevalence of cannabis abuse is higher in patients with attention deficit/hyperactivity disorder (ADHD) than in the general population, yet, knowledge about the motivational properties of cannabinoids in animal models of ADHD are lacking. OBJECTIVE: To compare the motivational effects of the synthetic cannabinoid agonist WIN55,212-2 (WIN) in adolescent and adult spontaneously hypertensive rats (SHR), a validated animal model of ADHD, and Wistar rats, representing a "normal" genetically heterogeneous population. We also asked whether the effects of WIN depended (1) on the activation of the cerebral subtype of cannabinoid receptors, namely, the CB(1) cannabinoid receptor and (2) on putative changes by WIN in blood pressure. METHODS: WIN was tested under an unbiased conditioned place preference (CPP) paradigm. Blood pressure after WIN administration was also monitored in additional groups of rats. RESULTS: In the Wistar rats, WIN produced place aversion only in the adult but not adolescent rats. In contrast, WIN produced CPP in both adolescent and adult SHR rats. The behavioral effects of WIN were CB(1)-mediated and not related to blood pressure. CONCLUSION: The contrasting effects of WIN in Wistar and SHR, and the higher resistance of adolescent rats to the aversive and rewarding effects of WIN in these two strains suggests that both adolescence and the ADHD-like profile exhibited by the SHR strain constitute factors that influence the motivational properties of cannabinoids.

Cannabinoid agonists stimulate [3H]GABA release in the globus pallidus of the rat when G(i) protein-receptor coupling is restricted: role of dopamine D2 receptors.

The motor effects of cannabinoids in the globus pallidus appear to be caused by increases in interstitial GABA. To elucidate the mechanism of this response, we investigated the effect of the selective cannabinoid type 1 receptor (CB1) cannabinoid agonist arachidonyl-2-chloroethylamide (ACEA) on [(3)H]GABA release in slices of the rat globus pallidus. ACEA had two effects: concentrations between 10(-8) and 10(-6) M stimulated release, whereas higher concentrations (IC(50) approximately 10(-6) M) inhibited it. Another cannabinoid agonist, WIN-55,212-2, also had bimodal effects on release. Studies of cAMP production indicate that under conditions of low G(i/o), availability the coupling of CB1 receptors with G(i/o) proteins can be changed into CB1:G(s/olf) coupling; therefore, we determined the effects of conditions that limit G(i/o) availability on [(3)H]GABA release. Blockers of G(i/o) protein interactions, pertussis toxin and N-ethylmaleimide, transformed the inhibitory effects of ACEA on GABA release into stimulation. It also has been suggested that stimulation of D2 receptors can reduce G(i/o) availability. Blocking D2 receptors with sulpiride [(S)-5-aminosulfonyl-N-[(1-ethyl-2-pyrrolidinyl)methyl]-2-methoxybenzamidersqb] or depleting dopamine with reserpine inhibited the ACEA-induced stimulation of release. Thus, the D2 dependence of stimulation is consistent with the proposal that D2 receptors reduce G(i/o) proteins available for binding to the CB1 receptor. In summary, CB1 receptor activation has dual effects on GABA release in the globus pallidus. Low concentrations stimulate release through a process that depends on activation of dopamine D2 receptors that may limit G(i/o) protein availability. Higher concentrations of cannabinoid inhibit GABA release through mechanisms that are independent of D2 receptor activation.

Avoidance of Abeta[(25-35)] / (H(2)O(2)) -induced apoptosis in lymphocytes by the cannabinoid agonists CP55,940 and JWH-015 via receptor-independent and PI3K-dependent mechanisms: role of NF-kappaB and p53.

Cannabinoids have been suggested as potential neuroprotective compounds in Alzheimer's disease (AD). Despite intense investigation, the detailed intracellular mechanism(s) involved in cannabinoids survival effect remains to be elucidated. The present study shows that CP55,940 (a CB1 and CB2 agonist) and JWH-015 (a CB2 agonist) protect and rescue peripheral blood lymphocytes (PBL) from (10 microM) Abeta[(25-35)] and (50 microM) H(2)O(2)-induced apoptosis by two alternative mechanisms: (1) receptor-independent pathway, as demonstrated by no-dihydrorhodamine oxidation into fluorescent rhodamine 123 (R-123) as a result of cannabinoid inhibition of Abeta-generated H(2)O(2); (2) receptor-dependent pathway through NF-kappaB activation and p53 down regulation involving phosphoinositide 3-kinase (PI-3K), as demonstrated by using either (25 microM) LY294002 (a PI-3K inhibitor), (50 nM) pifithrin-alpha (PFT, a specific p53 inhibitor) or by using immunocytochemistry detection of NF-kappaB and p53 transcription factors activation. Importantly, cannabinoid agonists and PFT were able to protect and rescue lymphocytes pre-exposed to toxicants-, even when the three compounds were added up-to 12 h post-Abeta[(25-35)]/(H(2)O(2)) exposure. These results suggest that CP55,940/( JWH-015) protection/rescue of PBL from noxious stimuli is determined by p53 inactivation. These findings may contribute to a better understanding of the role played by cannabinoids as neuroprotective agents to target and interrupt molecular signaling that induce damage in AD disorder.