Flavonoid Myricetin Modulates 𝐆𝐀𝐁𝐀_𝐀 Receptor Activity through Activation of 𝐂𝐚^𝟐+ Channels and CaMK-II Pathway

Figure 3

Myricetin activates L-type and T-type Ca²⁺ channels in PVN neurons. (a) Representative recording showing Ca²⁺ current changes in the absence and presence of myricetin (5 μg/mL) in a typical neuron. (b) The statistical data (t-test) demonstrate a significant increase of peak current after treatment with myricetin (𝑛=8, *𝑃<0.05). (c) Effects of myricetin on the Ca²⁺ channel properties in PVN neurons. The current was recorded in response to a 500 ms ramp pulse depolarization from a holding potential of −80 mV to +60 mV, the peak current was increased and shifted to hyperpolarizing direction after myricetin treatment. (d) Summarized current-voltage relationship curves showed the currents amplitude was increased in the region between −30 mV and −10 mV; the peak currents were shifted about 10 mV to negative direction (𝑛=10, *𝑃<0.05, **𝑃<0.01). (e) Effects of myricetin on the different types of Ca²⁺ currents in PVN neurons. Representative recording showing the currents changes in the presence (red color) and absence (black color) of myricetin. Myricetin enhanced both T-type and L-type Ca²⁺ currents. The currents were recorded in response to a pulse shown in this figure. The first part of the current can be blocked by 300 μM NiCl₂ (𝑛=3) and the second part can be blocked by 30 μM nifedipine (𝑛=3) (blue color). (f) The pooled data summarize the effect of myricetin on Ca²⁺ currents when depolarized to −40 mV from a holding potential of −80 mV compared that of control condition (𝑛=8, *𝑃<0.05).

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