SUN-163 - The Role of Non-Classical Renin Angiotensin System in Insulin Resistance in PCOS

Background: Polycystic ovary syndrome (PCOS) is characterized by hyperandrogenemia, obesity, and insulin resistance (IR). The renin–angiotensin system (RAS) regulates metabolic homeostasis via opposing actions of angiotensin II (Ang II) and angiotensin 1–7 (Ang 1–7). Ang 1-7 ameliorates IR in obese models. Although RAS dysregulation has been reported in women with PCOS and across multiple organs in animal models, comprehensive profiling of circulating RAS peptides is lacking, and whether Ang 1–7 ameliorates IR in a hyperandrogenemic PCOS model remains unclear.

Objective: To comprehensively profile circulating RAS peptides and assess their association with androgen levels, and to determine whether Ang 1–7 mitigates IR, using a well-characterized hyperandrogenemic female (HAF) rat model of PCOS.

Methods: Four-week-old female Sprague-Dawley rats (n=8/group) received empty or dihydrotestosterone (DHT) implants (8 mg, SC) with vehicle or Ang 1-7 (500 µg/kg/day, SC minipump). Fasting glucose (colorimetry) and fasting insulin (ELISA) were measured, and HOMA-IR was calculated. Serum RAS peptides (Ang I, Ang II, Ang 1–7) were quantified by LC–MS, and plasma renin activity (PRA), ACE, and ACE2 activities were calculated. Circulating DHT was quantified by radioimmunoassay. Urinary and serum angiotensinogen (AGT) were measured by ELISA. Pearson correlation was used to assess relationships between relevant variables.

Results: DHT significantly increased fasting insulin (0.8±0.05 vs. 0.6±0.06 ng/mL) and HOMA-IR (5.5±0.3 vs. 3.8±0.5) without altering fasting glucose. This metabolic dysfunction was associated with significantly lower circulatory Ang I in DHT rats compared to controls (222±50 vs. 566±171 pmol/L), Ang II (286±78 vs. 401±95 pmol/L), Ang 1-7 (8±1 vs. 15±5 pmol/L), and PRA (591±155 vs. 1263±379 pmol/L). Despite these reductions, ACE activity (1.2 ± 0.1 vs. 1.5 ± 0.2) and ACE2 activity (0.13±0.01 vs. 0.16±0.02) were preserved. Ang 1-7 infusion did not modify IR or the individual RAS peptide concentrations in HAF rats.

Conclusions: Hyperandrogenemia induces IR and establishes a distinct systemic RAS fingerprint marked by suppression of both classical and non-classical RAS. Despite reduced endogenous Ang 1–7, its supplementation failed to improve glucose homeostasis or restore RAS activity, indicating that androgen excess blunts its metabolic effects. The positive association between serum DHT and urinary angiotensinogen identifies urinary AGT as a potential biomarker of hyperandrogenemia-driven RAS activation. Together, these findings highlight hyperandrogenemia as a primary driver of systemic RAS dysregulation and insulin resistance in PCOS and suggest that therapies targeting androgen excess or classical RAS blockade may be more effective than non-classical RAS activation for improving metabolic outcomes.