Microcystin (-LR) affects hormones level of male mice by damaging hypothalamic-pituitary system

Microcystin (-LR) (MC-LR) is a broad distributed hepatotoxic microcystin produced by common freshwater phytoplankton species. Recently, its toxic effects on male reproductive system drew great attention. To investigate its reproductive toxicity and the underlying mechanism, BALB/c mice were exposed to MC-LR by intraperitoneal injection with different injection duration (1, 4, 7 and 14 days) and injection concentration (3.75, 7.5, 15 and 30 μg kg b.w.(-1) day(-1)) as an in vivo test. For in vitro test, isolated mice Leydig cells were exposed to MC-LR at doses of 1, 10, 100, 250, 500 750 and 1000 nmol/L for 24 h. MC-LR did not induce significant changes in Kiss-1, GPR54, Gnrhr, Fshr or Lhr expression. It decreased the Gnrh expression in a dose- and duration-dependent manner. It increased and subsequently decreased the expressions of FSH, LH and testosterone. In in vivo test, MC-LR was not able to enter Leydig cells and had no cytotoxicity on Leydig cells. The results showed that MC-LR affected male mice serum hormones and mRNA expressions by damaging the hypothalamic-pituitary systems.