Biological and Toxicological Evaluation of N-(4methyl-phenyl)-4-methylphthalimide on Bone Cancer in Mice.

BACKGROUND: It was recently demonstrated that the phthalimide N-(4-methyl-phenyl)-4- methylphthalimide (MPMPH-1) has important effects against acute and chronic pain in mice, with a mechanism of action correlated to adenylyl cyclase inhibition. Furthermore, it was also demonstrated that phthalimide derivatives presented antiproliferative and anti-tumor effects. Considering the literature data, the present study evaluated the effects of MPMPH-1 on breast cancer bone metastasis and correlated painful symptom, and provided additional toxicological information about the compound and its possible metabolites. METHODS: In silico toxicological analysis was supported by in vitro and in vivo experiments to demonstrate the anti-tumor and anti-hypersensitivity effects of the compound. RESULTS: The data obtained with the in silico toxicological analysis demonstrated that MPMPH-1 has mutagenic potential, with a low to moderate level of confidence. The mutagenicity potential was in vivo confirmed by micronucleus assay. MPMPH-1 treatments in the breast cancer bone metastasis model were able to prevent the osteoclastic resorption of bone matrix. Regarding cartilage, degradation was considerably reduced within the zoledronic acid group, while in MPMPH-1, chondrocyte multiplication was observed in random areas, suggesting bone regeneration. Additionally, the repeated treatment of mice with MPMPH-1 (10 mg/kg, i.p.), once a day for up to 36 days, significantly reduces the hypersensitivity in animals with breast cancer bone metastasis. CONCLUSION: Together, the data herein obtained show that MPMPH-1 is relatively safe, and significantly control the cancer growth, allied to the reduction in bone reabsorption and stimulation of bone and cartilage regeneration. MPMPH-1 effects may be linked, at least in part, to the ability of the compound to interfere with adenylylcyclase pathway activation.

Plant derived alkaloid (-)-cassine induces anti-inflammatory and anti-hyperalgesics effects in both acute and chronic inflammatory and neuropathic pain models.

Natural products have been revealed as relevant sources of therapeutic agents including those for the management of pain states. In this study, the anti-nociceptive and anti-inflammatory effects of (-)-cassine, isolated from Senna spectabilis were evaluated using pharmacological, behavioural and biochemical approaches. Oral treatment with (-)-cassine (3-30 mg/kg) reduced carrageenan-induced mechanical and thermal nociception associated with the suppression of myeloperoxidase activity in the mouse paw. Moreover, (-)-cassine (1-10 µg/site) prevented mechanical hyperalgesia induced by carrageenan when given through the intraplantar (i.pl.), spinal and intracerebroventricular routes. Additionally, oral treatment with (-)-cassine (3-60 mg/kg) prevented the mechanical hyperalgesia elicited by intraplantar injection of prostaglandin E(2), complete Freund's adjuvant, interleukin-1ß, interleukin-6 and keratinocyte-derived chemokine. Furthermore, (-)-cassine inhibited the mechanical nociceptive response induced by ligation of the sciatic nerve and also significantly reduced the levels of cytokines/chemokines in paw tissue following i.pl. injection of carrageenan. In addition, the anti-nociceptive and anti-inflammatory actions of (-)-cassine were associated with its ability to interact with both TRPV1 and TRPA1 receptors and by inhibiting the upregulation of cyclooxigenase-2 as well as inhibiting the phosphorylation of MAPK/ERK and the transcription factor NF-κB. It is important to highlight that oral treatment with (-)-cassine did not produce any effects related to temperature, locomotor activity or catalepsy. Altogether, the present data demonstrate that (-)-cassine has systemic, spinal and supraspinal anti-nociceptive properties when assessed in inflammatory and neuropathic pain models. These effects are associated with its ability to block several signalling pathways associated with inflammatory and nociceptive responses. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'.

Cannabinoid agonists inhibit neuropathic pain induced by brachial plexus avulsion in mice by affecting glial cells and MAP kinases.

BACKGROUND: Many studies have shown the antinociceptive effects of cannabinoid (CB) agonists in different models of pain. Herein, we have investigated their relevance in neuropathic pain induced by brachial plexus avulsion (BPA) in mice. METHODOLOGY/PRINCIPAL FINDINGS: Mice underwent BPA or sham surgery. The mRNA levels and protein expression of CB(1) and CB(2) receptors were assessed by RT-PCR and immunohistochemistry, respectively. The activation of glial cells, MAP kinases and transcription factors were evaluated by immunohistochemistry. The antinociceptive properties induced by cannabinoid agonists were assessed on the 5(th) and 30(th) days after surgery. We observed a marked increase in CB(1) and CB(2) receptor mRNA and protein expression in the spinal cord and dorsal root ganglion, either at the 5(th) or 30(th) day after surgery. BPA also induced a marked activation of p38 and JNK MAP kinases (on the 30(th) day), glial cells, such as microglia and astrocytes, and the transcription factors CREB and NF-κB (at the 5(th) and 30(th) days) in the spinal cord. Systemic treatment with cannabinoid agonists reduced mechanical allodynia on both the 5(th) and 30(th) days after surgery, but the greatest results were observed by using central routes of administration, especially at the 30(th) day. Treatment with WIN 55,212-2 prevented the activation of both glial cells and MAP kinases, associated with an enhancement of CREB and NF-κB activation. CONCLUSIONS/SIGNIFICANCE: Our results indicate a relevant role for cannabinoid agonists in BPA, reinforcing their potential therapeutic relevance for the management of chronic pain states.