Ginkgo biloba extract modulates astrocytic and microglial recruitment in the hippocampus and hypothalamus of menopause-induced ovariectomized rats.

Background: Changes in steroid hormone levels associated with menopause are known to affect body composition, with increased accumulation of visceral fat and impaired actions of appetite-regulating neuropeptides. Anti-obesogenic, antioxidant, anti-inflammatory and neuromodulatory properties have been attributed to Ginkgo biloba extract (GbE) oral supplementation.

Hypothesis/purpose: We investigated in menopause-induced ovariectomized rats the effects of GbE oral supplementation on microglial reactivity and astrocyte recruitment in hippocampal and hypothalamic subregions involved in the regulation of feeding behavior and energy homeostasis.

Study Design/methods: Ovariectomy (Ovx) or false-Ovx (Sham) surgery were performed in 2-month-old female Wistar rats. Sixty days after surgery, Ovx rats were gavaged daily for 14 days with either saline (Ovx + Veh) or GbE 500 mg/Kg (Ovx + GbE). Rats were subsequently sacrificed, brains harvested and subjected to immunohistochemistry and immunofluorescence analyses.

Results: Ovx increased microglial reactivity in CA1, CA3 and dentate gyrus (DG) in the dorsal hippocampal formation (dHF), as well as in DG in the ventral hippocampal formation (vHF). Additionally, Ovx reduced astrocyte count in dHF CA3. The disturbances found in Ovx + Veh versus Sham were not found in Ovx + GbE versus Sham. Furthermore, higher astrocyte counts in DG of both dHF and vHF were found in Ovx + GbE as compared to Ovx + Veh. In the hypothalamus, Ovx + Veh showed reduced microglial reactivity in the arcuate (ARC) and ventromedial (VMH) nuclei as compared to Ovx + GbE. Ovx + GbE rats presented higher astrocyte counts in ARC compared to Sham rats.

Conclusion: Our results show for the first time in a rodent model of menopause that GbE supplementation modulates astrocyte and microglial recruitment and reactivity in hippocampal and hypothalamic subregions involved in feeding behavior and energy homeostasis. Future research employing other experimental models may further elucidate whether GbE supplementation possesses therapeutic properties upon glial cell reactivity to potentially alleviate changes in energy homeostasis associated with menopause.