Figure 4.

ADP inhibits GnRH neuronal activity via AMPK. A, Schematic representation. AMPK is activated via the AdipoR or by AICAR, an AMPK agonist, whereas CC, an AMPK antagonist, inhibits AMPK phosphorylation. B, AMPK subunits are expressed in single GnRH cells. PCR on cDNAs from single cells shows bands of appropriate size for AMPK α2, β1 and γ1 (M, marker; Br, brain; sGc, single GnRH cell). C, Expression of AMPK subunits varies among GnRH cells. D, AICAR decreases the frequency of calcium oscillations in GnRH neurons similar to ADP, whereas CC prevents the inhibitory ADP effect. E₁ and E₂ Representative calcium traces. E₁, Spontaneous baseline oscillations in intracellular calcium levels during 10 minutes of SFM and subsequent decrease in activity during 10 minutes of AICAR (500μM) application. E₂, CC (5μM, 10 min) had no effect on GnRH calcium activity, but coapplication of CC with ADP (500 ng/mL) prevented inhibition.