Oxidative imbalance in mice intoxicated by microcystin-LR can be minimized

Single microcystin exposure impairs the hypothalamic-pituitary-gonadal axis at different levels in female rats

Microcystin (MC) is most common cyanobacterial toxin. Few studies have evaluated the MC effects on the hypothalamic-pituitary-gonadal (HPG) axis and metabolic function. In this study, we assessed whether MC exposure results in HPG axis and metabolic changes. Female rats were exposed to a single dose of MC at environmentally relevant levels (5, 20 and 40 μg/kg). After 24 h, we evaluated reproductive and metabolic parameters for 15 days. MC reduced the hypothalamic GnRH protein expression, increased the pituitary protein expression of GnRHr and IL-6. MC reduced LH levels and increased FSH levels. MC reduced the primary follicles, increased the corpora lutea, elevated levels of anti-Müllerian hormone (AMH) and progesterone, and decreased estrogen levels. MC increased ovarian VEGFr, LHr, AMH, ED1, IL-6 and Gp91-phox protein expression. MC increased uterine area and reduced endometrial gland number. A blunted estrogen-negative feedback was observed in MC rats after ovariectomy, with no changes in LH levels compared to intact MC rats. Therefore, these data suggest that a MC leads to abnormal HPG axis function in female rats.

Subacute and sublethal ingestion of microcystin-LR impairs lung mitochondrial function by an oligomycin-like effect

Microcystin-LR (MC-LR) is a potent cyanotoxin that can reach several organs. However subacute exposure to sublethal doses of MC-LR has not yet well been studied. Herein, we evaluated the outcomes of subacute and sublethal MC-LR exposure on lungs. Male BALB/c mice were exposed to MC-LR by gavage (30 µg/kg) for 20 consecutive days, whereas CTRL mice received filtered water. Respiratory mechanics was not altered in MC-LR group, but histopathology disclosed increased collagen deposition, immunological cell infiltration, and higher percentage of collapsed alveoli. Mitochondrial function was extensively affected in MC-LR animals. Additionally, a direct in vitro titration of MC-LR revealed impaired mitochondrial function. In conclusion, MC-LR presented an intense deleterious effect on lung mitochondrial function and histology. Furthermore, MC-LR seems to exert an oligomycin-like effect in lung mitochondria. This study opens new perspectives for the understanding of the putative pulmonary initial mechanisms of damage resulting from oral MC-LR intoxication.

LASSBio-596: a New Pre-clinical Candidate for Rheumatoid Arthritis?

Pain and inflammatory disorders are significant health problems because of prevalence and associated disabilities. In this context, LASSBio-596 is a hybrid compound able to modulate TNF-α and phosphodiesterases 4 and 5, exhibiting an anti-inflammatory effect in the pulmonary inflammatory model. Aiming at a better description of the activities of LASSBio-596, we initially conducted nociception tests (acetic acid-induced abdominal writhing, glutamate, and formalin-induced nociception and hot plate test) and later inflammatory tests (acute, peritonitis; and chronic, arthritis) that directed us to this last one. In the abdominal writhing test, there was a dose-dependent inhibition, whose response occurred at the maximum dose (50 mg/kg, p.o.), used in the subsequent tests. LASSBio-596 also inhibited nociception induced by chemical (glutamate by 31.9%; and formalin, in both phases, 1st phase: 25.7%; 2nd phase: 23.9%) and thermal agents (hotplate, by increased latency for pain at two different times). These effects were independent of the motor function, legitimated in rotarod. As there was a response in the inflammatory component of nociception, we performed the peritonitis test, in which migration was inhibited by LASSBio-596 by 39.9%. As the inflammatory process is present in autoimmune diseases, we also performed the arthritis test. LASSBio-596 reduced paw edema from the 15th day to the 21st day of treatment (no liver changes and with fewer paw injuries). In addition, LASSBio-596 decreased serum levels of TNF-α by 67.1%. These data demonstrated the antinociceptive effect of LASSBio-596 and reinforces its anti-inflammatory property (i.e., RA), amplifying the therapeutic potential of this molecule.