Brief mechanical pulses induce sustained intracellular L-lactate production in astrocytes

Intracranial-pressure transients impose mechanical strain on perivascular astrocytes, but it is unclear whether brief mechanical events elicit metabolic responses. Here, we applied 1.5-s pressure-driven mechanical stimuli (5-1,000 hPa) to cultured primary rat cortical astrocytes using a patch-micropipette microinjector and monitored cytosolic lactate ([lactate]_i) with a Förster resonance energy transfer Laconic nanosensor. Single pressure pulses (5-1,000 hPa) evoked a pressure-dependent increase in [lactate]_i that persisted for minutes after stimulation, reaching a steady-state increase of 0.3-4.1% relative to baseline over 200-300 s. Sequential pulses delivered to the same cell produced transient spikes followed by stepwise increases in the post-stimulus plateau, yielding an estimated activation threshold of ~4-5 hPa. Transient receptor-potential vanilloid-4 (TRPV4) immunoreactivity was detected in cultured astrocytes, and pharmacologic inhibition of TRPV4 with HC-067047 attenuated mechanically evoked lactate accumulation during mechanical stimulation by solution bolus addition. These findings demonstrate that astrocytes convert brief mechanical stimuli into prolonged cytosolic lactate increases, supporting a contribution of TRPV4-associated mechanosensitive signaling to astrocytic mechano-metabolic integration.