Theanine enhanced both the toxicity of strychnine and anticonvulsion of pentobarbital sodium

Context: Theanine, an additive, holds several effects on the central nervous system without toxicity and affects CNS drugs. Theanine bilaterally alters β wave of the EEG with or without caffeine and pentobarbital-induced locomotor activity. Theanine also enhances hypnosis of pentobarbital sodium (PB) and antidepression of midazolam, suggesting there are complicated interactions between theanine and CNS drugs. On the other side, theanine induces glycine release. Glycine potentiates the strychnine toxicity via NMDA receptor activation. Moreover, PB facilitates GABA_A receptor activation by GABA, and it is commonly prescribed for strychnine poison. However, what the role that theanine plays in the anticonvulsion of PB against strychnine poison is still unknown. Materials and methods: Theanine, pentobarbital sodium or strychnine was injected intraperitoneally. EEG was monitored by BIOPAC 16 EEG amplifiers. LD₅₀ of strychnine and hypnotic ED₅₀ of pentobarbital sodium with or without theanine for mice were tested according to Bliss’ case. Results: (1) Theanine enhanced the strychnine toxicity. Both theanine and strychnine 1.0?mg/kg increased the power of the β wave. Theanine aggravated that of strychnine 1.0?mg/kg. Theanine attenuated the LD₅₀ of strychnine. (2) Theanine enhanced the anticonvulsion of PB. Theanine increased the power of α, β wave and decreased hypnotic ED₅₀ of PB; PB attenuated strychnine-induced EEG excitation and mortality with or without theanine, and theanine enhanced the effects of PB. Further, theanine enhanced the anticonvulsion of PB dose-dependently against the strychnine toxicity but not the lethal toxicity of strychnine. Discussion and conclusions: These results indicated theanine interacted with PB and strychnine. Theanine enhanced both the strychnine toxicity and anticonvulsion of PB against strychnine poison.