Estrogen receptor GPER1 eases hypertension in menopausal mice via hypothalamic GluA1

When women pass through menopause, their risk of hypertension climbs sharply, yet the brain-based mechanisms driving this transition have remained largely hidden from science. A new mouse study now reveals that a little-known membrane estrogen receptor, GPER1, acts as a molecular brake on the hypothalamic neurons that drive blood pressure — and that this braking system works in postmenopausal females but not in males. The finding, published in Biology of Sex Differences, offers one of the most detailed pictures yet of how the brain generates sex-specific hypertension after ovarian failure.

Researchers at Weill Cornell Medicine, led by Teresa A. Milner and Michael J. Glass, set out to dissect why blood pressure control goes awry when estrogen declines. Studying hypertension in female animals has long been hampered by a modeling problem: surgically removing the ovaries produces an abrupt hormonal cliff that does not resemble natural menopause, while simply aging rodents produces a partial hormone decline mixed with the confounding effects of chronological aging. To get around this, the team used a chemical called 4-vinylcyclohexene diepoxide, or VCD, which selectively destroys ovarian follicles and produces a staged hormonal decline. In this model, mice first pass through a phase resembling perimenopause, with irregular estrogen fluctuations, and then reach a phase termed post-accelerated ovarian failure, in which estrogen is undetectable, progesterone is reduced, and pituitary hormones are elevated — a hormonal profile closely mirroring human postmenopause.

The team then induced hypertension using a slow-pressor regimen of angiotensin II, delivered by osmotic minipump over fourteen days at a dose that gradually raises blood pressure. Systolic blood pressure was tracked by tail-cuff plethysmography. Both post-menopausal model females and age-matched males developed comparable hypertension in response to the hormone. But when the researchers peered into the paraventricular nucleus of the hypothalamus — a command center housing neurons that project to the spinal cord and drive the sympathetic nervous system — they found that the two sexes had arrived at high blood pressure by fundamentally different neural routes.

Using whole-cell voltage-clamp electrophysiology on brain slices, the researchers recorded from spinally-projecting PVN neurons that had been retrogradely labeled with a fluorescent tracer. In hypertensive post-menopausal females, the surprise was what did not change: NMDA receptor-mediated currents were unaltered, in contrast to previous findings in earlier stages of ovarian decline where NMDA signaling dominates. Instead, AMPA receptor currents — fast excitatory signaling mediated by the GluA1 subunit — were selectively elevated. Blocking calcium-permeable, GluA2-lacking AMPA receptors with the spider-toxin-derived antagonist Naspm abolished this difference, pinpointing the AMPA receptor subtype responsible. In males, by contrast, hypertension recruited both AMPA and NMDA currents, consistent with earlier work, and the relative amplification of AMPA signaling was even greater than in females.

The molecular machinery behind these currents proved equally revealing. GluA1-containing AMPA receptors are tethered at the neuronal plasma membrane by AKAP150, a scaffolding protein that anchors protein kinase A and other effectors. When the researchers disrupted the AKAP150–PKA interface with the cell-permeable peptide st-Ht31, the heightened AMPA currents in hypertensive animals of both sexes collapsed back toward baseline — evidence that a shared scaffold supports the hypertensive response in both groups. Genetically silencing GluA1 in the PVN with an adeno-associated virus expressing a short hairpin RNA blunted the blood pressure rise in post-menopausal females, confirming that this receptor is not merely a correlate of hypertension but a functional contributor.

Beyond the electrophysiology, the team deployed electron microscopy with immunogold labeling to map exactly where AKAP150 sits within dendrites. In small, distal dendrites of PVN neurons — the compartments that receive dense excitatory input — hypertensive post-menopausal females showed a striking increase in AKAP150 particles parked directly on the plasma membrane. Males showed no such redistribution. At the gene level, the picture inverted: hypertensive males, but not females, showed increased expression of Prkaca, the gene encoding the catalytic subunit of PKA. Consistent with this, mutating the Ser845 phosphorylation site on GluA1 — the residue PKA modifies to control receptor trafficking to the membrane — slightly but significantly reduced hypertension in male mice while leaving the female response untouched.

Here the story took an unexpected turn toward estrogen biology. Estrogen can act not only through classic nuclear receptors but through GPER1, a G-protein-coupled receptor that resides at the plasma membrane and is known to associate with the AKAP150 complex. Because estrogen is essentially absent in post-menopausal model females, the researchers hypothesized that GPER1, though unliganded, might still be positioned to modulate AMPA signaling if artificially activated. When they applied G-1, a selective GPER1 agonist, to slices from hypertensive post-menopausal females, the elevated AMPA currents in PVN projection neurons were significantly suppressed.

The whole-animal results were even more dramatic. Cyclically administering G-1 alongside the fourteen-day angiotensin II infusion completely prevented the rise in systolic blood pressure in post-menopausal females — while having no effect whatsoever in hypertensive males. GPER1 stimulation also increased expression of Akap5, the gene encoding AKAP150, in the PVN of females regardless of whether they were hypertensive, suggesting the receptor reshapes its own signaling platform. Notably, activating estrogen receptor beta with the agonists DPN or ERB-041 neither reduced AMPA currents nor lowered blood pressure in these animals, indicating that the protective effect at this late stage of ovarian failure is GPER1-specific and that different estrogen receptors govern different phases of the menopausal transition.

Taken together, the study sketches a striking biological divergence: two sexes develop the same measurable hypertension through a common hypothalamic hub, yet one relies on a classical PKA–Ser845 pathway while the other depends on an unconventional AMPA–AKAP150–GPER1 signaling axis that can be pharmacologically disengaged. The findings help explain why hypertension vulnerability in women shifts across the life course, from a protected state during reproductive years to heightened risk after menopause, and why earlier stages of ovarian decline appear governed by entirely different receptor systems. They also carry translational weight: a hypofunctional variant of the human GPER1 gene has been linked to elevated blood pressure in women specifically. If the mouse findings hold in humans, targeting GPER1 could one day offer a precision approach to treating the hypertension that shadows so many women after menopause — one that respects the fact that, at the level of the hypothalamus, male and female brains are solving the same problem with different molecular tools.