Teriparatide reduces spinal neuroinflammatory phenotypes in ovariectomized rats revealed by an artificial intelligence-driven glial cell morphometry of bright-field tissue sections

Osteoporosis frequently presents with lower back pain, often accompanied by hypersensitivity, even in the absence of vertebral fractures, suggesting the involvement of central neuroinflammatory mechanisms. The activation of spinal glia has been implicated as a key driver of pain. Clinical and preclinical studies have also shown that teriparatide (TPTD), a bone anabolic drug, alleviates osteoporotic pain and raises the possibility of anti-neuroinflammatory effects. We previously reported that TPTD suppresses neuroinflammatory microglial proliferation in the spinal dorsal horn of an ovariectomized (OVX) rat model of postmenopausal osteoporosis. To further substantiate these previous findings, this study morphometrically investigated neuroinflammatory alterations in the same patho-pharmacological setting by establishing an AI-driven morphometric pipeline applied to DAB-stained bright-field images. OVX increased the number of microglia, induced process shortening and higher circularity, and expanded GFAP-positive astrocytic areas. TPTD partially attenuated OVX-induced glial changes. These findings indicate that OVX induces spinal neuroinflammation involving both microglia and astrocytes and that TPTD mitigates these neuroinflammatory responses. Moreover, the combination of 2D bright-field imaging and AI-driven morphometry represents a practical, accessible approach that requires minimal specialized equipment, yet sensitively captures OVX- and TPTD-induced microglial alterations, and enables phenotype-based classification.