Protective Capability of Astragalus (Huangqi) on Auditory Function in a Rat Model of Estrogen Deficiency
For many women, estrogen deficiency—whether from menopause, ovariectomy, or ovarian failure—can bring unexpected health challenges. One area of growing research? How it affects hearing, especially when combined with ototoxic drugs like cisplatin, a common cancer treatment. While studies on estrogen’s direct link to hearing have mixed results, one thing is clear: when estrogen-deficient women take cisplatin, their risk of hearing damage rises. Now, new research suggests a traditional Chinese herb—Astragalus (Huangqi)—may help protect against this harm, with effects similar to estrogen therapy.
Led by Dr. Xu-Jun Hu from the College of Medical Technology at Zhejiang Chinese Medical University in Hangzhou, China, the study aimed to test Astragalus’ ability to shield auditory function in ovariectomized (estrogen-deficient) rats treated with cisplatin. For comparison, researchers also looked at estrogen therapy (estradiol alone), a standard approach for some estrogen-related issues.
How the Study Worked
The team used 48 female Sprague-Dawley rats (2 months old, 180–200g) divided into four groups:
- Sham: No ovariectomy or cisplatin (control group).
- OVX: Ovariectomized (estrogen-deficient) + cisplatin.
- OVX+H: Ovariectomized + cisplatin + daily Astragalus extract injections (5mL/kg body weight).
- OVX+E: Ovariectomized + cisplatin + daily estradiol valerate (0.1mg/kg body weight, given by gavage).
Three weeks after ovariectomy, all OVX, OVX+H, and OVX+E rats received cisplatin (5mg/kg daily for 4 days)—a typical chemotherapy cycle. Auditory function was tested 24 hours later using two key tools:
- DPOAE (Distortion Product Otoacoustic Emissions): Measures cochlear (inner ear) function by recording responses to two pure tones. A higher signal-to-noise ratio (SNR) means better inner ear health.
- ABR (Auditory Brainstem Responses): Tracks how well sound travels to the brainstem via electrical signals from the scalp. Lower hearing thresholds mean better central auditory function.
All procedures were approved by a university animal ethics committee, and animals were monitored daily for hydration and warmth during anesthesia.
Key Findings: Astragalus Protects Hearing
The results, published in the Chinese Medical Journal, highlighted clear differences:
- OVX vs. Sham: Estrogen-deficient rats (OVX) had significantly worse cochlear function (lower SNR in DPOAE) and higher hearing thresholds (worse brainstem processing) compared to the sham group. This confirms cisplatin amplifies hearing damage in estrogen-deficient individuals.
- Astragalus vs. No Therapy: The OVX+H group (Astragalus) showed better cochlear function (higher SNR at 2 and 8 kHz) than the OVX group. For central auditory function (ABR), OVX+H had lower thresholds across most frequencies—meaning sound traveled more effectively to the brain.
- Astragalus vs. Estrogen: Both therapies improved outcomes. Estrogen (OVX+E) had slightly broader benefits (better SNR at 2, 4, 6, and 8 kHz), but Astragalus matched estrogen’s effect on ABR thresholds—protecting both the inner ear and brain pathways.
What This Means for You
The study’s takeaway is promising: For estrogen-deficient individuals (like women in menopause or post-ovariectomy), Astragalus may offer a natural way to protect hearing during cisplatin treatment. Its active compounds—polysaccharides, astragalosides, and flavonoids—are thought to drive these benefits. Importantly, Astragalus is known for milder side effects than estrogen therapy, making it a potential alternative for those who can’t or prefer not to take hormones.
Dr. Hu notes a key limitation: The study used Astragalus alone, while in clinical practice, it’s often combined with other herbs. More research is needed to see how combinations affect hearing protection.
The Bigger Picture
This research adds to growing evidence that traditional herbs like Astragalus can play a role in modern medicine—especially for managing chemotherapy side effects. For women navigating estrogen deficiency and cancer treatment, it offers hope that a centuries-old herb could help preserve a vital sense: hearing.
Published in the Chinese Medical Journal (2019) by Dr. Xu-Jun Hu, College of Medical Technology, Zhejiang Chinese Medical University.
doi.org/10.1097/CM9.0000000000000024
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