Caryne M. Bertollo

In vivo evidence for a role of protein kinase C in peripheral nociceptive processing

The present study was designed to characterize the nociceptive response induced by protein kinase C (PKC) peripheral activation and to investigate if this biochemical event is important for the nociceptive response induced by formaldehyde, and bradykinin (BK). Intraplantar injection of phorbol‐12,13‐didecanoate (PDD; 0.01, 0.1 or 1 μg), a PKC activator, but not of 4α‐PDD (inactive analogue), dose‐dependently induced thermal hyperalgesia in rats. This response was not observed at the contralateral hindpaw. Intraplantar injection of PDD (0.01, 0.1 or 1 μg) also induced mechanical allodynia. In mice, injection of PDD (0.1 or 1 μg) into the dorsum of the hindpaw induced a spontaneous licking behaviour. Intraplantar co‐injection of chelerythrine (10 or 50 μg), a PKC inhibitor, attenuated the thermal hyperalgesia induced by PDD (0.1 μg) in rats. The second phase of the nociceptive response induced by the injection of formaldehyde (0.92%, 20 μl) into the dorsum of mice hindpaws was inhibited by ipsi‐, but not contralateral, pre‐treatment with chelerythrine (1 μg). Intraplantar injection of BK (10 μg) induced mechanical allodynia in rats. Ipsi‐ but not contralateral injection of bisindolylmaleimide I (10 μg), a PKC inhibitor, inhibited BK‐induced mechanical allodynia. In conclusion, this study demonstrates that PKC activation at peripheral tissues leads to the development of spontaneous nociceptive response, thermal hyperalgesia and mechanical allodynia. Most importantly, it also gives in vivo evidence that peripheral PKC activation is essential for the full establishment of the nociceptive response induced by two different inflammatory stimuli.

Implication of eIF2α kinase GCN2 in induction of apoptosis and endoplasmic reticulum stress-responsive genes by sodium salicylate.

Sodium salicylate (NaSal) can disturb cell viability by affecting the activity of multiple cellular molecules. In this work, we investigated the involvement of stress‐responsive kinase GCN2 in regulating cell death and expression of stress genes in mouse embryonic fibroblasts (MEFs) upon exposure to NaSal.

Synthesis of novel 2,3,4-trisubstituted-oxazolidine derivatives and in vitro cytotoxic evaluation.

We have previously reported the discovery of cytotoxic and pro-apoptotic hit compound 1,1-dimethylethyl (S)- 2,2-dimethyl-4-[(3-nitrophenoxy)methyl]-3-oxazolidinecarboxylate 1 against leukemia cells. In the present work we describe the synthesis of 25 derivatives of this hit varying the substituent at ring or stereochemistry of the oxazolidine ring and evaluated them against human cancer cells lines. Six compounds exerted significant activity against HL60 promyelocytic leukemia cells with IC50 in low micromolar range (4-18 μM) and three compounds displayed activity against MDA-MB231 breast cancer cells (25-37 μM). In vitro cytotoxicity on normal cells PBMC (human peripheral blood mononuclear cells) was also evaluated. Compounds 7e (p-NO2, S) and 7m (p-COOCH3, S) showed good antiproliferative activity against HL60 (4 and 5 μM) and MDA-MB231 (37 and 25 μM) without affecting lymphocyte proliferation in PBMC, indicating low toxicity to normal cells. Besides, compound 7e induced DNA fragmentation on about 100% of HL60 cells at 50 μM. In this case, it was more potent than 7m and lead 1. This indicated that compound 7e has a great pro-apoptotic potential.

Thiamine and riboflavin inhibit production of cytokines and increase the anti-inflammatory activity of a corticosteroid in a chronic model of inflammation induced by complete Freund’s adjuvant

BACKGROUND The effects induced by thiamine and riboflavin, isolated or in association with corticosteroids, in models of chronic inflammation are not known. Thus, we evaluated the effect induced by these B vitamins, isolated or in association with dexamethasone, on the mechanical allodynia, paw edema and cytokine production induced by complete Freunds adjuvant (CFA) in rats. METHODS Chronic inflammation was induced by two injections of CFA. Nociceptive threshold, paw volume and body temperature were evaluated for 21days. Tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) contents were determined in paw tissue. Riboflavin (125, 250 or 500mg/kg) or thiamine (150, 300 or 600mg/kg) were administered per os (po), twice daily. Dexamethasone (0.5mg/kgday, po) was administered every three days. RESULTS CFA induced long lasting mechanical allodynia and paw edema. Elevation of body temperature was observed for a short period. Riboflavin reduced neither paw edema nor mechanical allodynia. Thiamine did not change paw edema, but partially inhibited mechanical allodynia. Riboflavin (500mg/kg) and thiamine (600mg/kg) exacerbated the anti-inflammatory activity of dexamethasone. Riboflavin, thiamine and dexamethasone reduced TNF-α and IL-6 production. The association of dexamethasone with thiamine induced greater inhibition of IL-6 production when compared with that induced by dexamethasone. CONCLUSIONS Riboflavin and thiamine exacerbate the anti-inflammatory activity of dexamethasone and reduce production of TNF-α and IL-6.