TGFB1 and Hyperammonemia: However, in hyperammonemic rats treated with bicuculline, the levels of both cytokines increased after five weeks of hyperammonemia, suggesting that chronic bicuculline can activate the regulatory T-cells that increase IL-10 and TGF-β levels in the plasma of hyperammonemic rats, whereas, in control rats, plasmatic levels of IL-10 were decreased by bicuculline chronic administration (Figure 1f,g).