The Long‐Term Impact of Ovariectomy on Ventilation and Expression of Phrenic Long‐Term Facilitation in Female Rats

Estrogen is necessary for the expression of phrenic long-term facilitation (pLTF) in female rats. pLTF, a well-studied model respiratory neuroplasticity, characterized by progressive increase nerve amplitude following acute intermittent hypoxia (AIH). Gonadally-intact, adult rats only develop pLTF stages estrous cycle with high levels circulating estrogen. Removal ovaries (ovariectomy, OVX), primary source estrogen females, also prevents AIH-induced and supplementation sufficient to restore OVX rats, supporting key role development pLTF. Respiratory neuroplasticity studies using are generally completed ~7-10 days post-OVX; timeframe surgery recovery significantly decline. However, few have explored impact on function or neuroplasticity. Here, we examined ventilation awake, freely behaving 12 weeks-post (or sham control surgeries) compared them 2 OVX. Our hypothesis was that chronic would minimal but continue impair Whole body plethysmography used measure baseline breathing (20.9% O2, N2 balance) ventilatory responses strong chemoreceptor stimulation (10% 5% CO2, balance). measures including frequency, tidal volume, minute ventilation, neural drive were measured between groups. Following plethysmography, recordings quantify Results indicate had little all experimental groups responded appropriately challenge during plethysmography. week showed significant volume relative (p≤0.001), different from other This production reflected calculation volume/inspiratory time, (p≤0.01) not ventilation. sustained effects plasticity, as group displayed indicated increased 60-min AIH (p≤0.001). higher than both (p≤0.01). ELISA assays correlation magnitude (p= 0.039) In summary, appears limit up weeks. Since no changes observed over these data consistent our prior work indicating plays