OLFACTORY BULBECTOMY INDUCES LONG-LASTING MECHANICAL AND COLD ALLODYNIA AND STRUCTURAL GLIAL ALTERATIONS IN THE BASOLATERAL AMYGDALA IN MALE RATS

Olfactory bulbectomy (OBX) is a well-established rodent model that reproduces behavioral features associated with agitated depression; however, most studies evaluate outcomes within 3–4 weeks post-lesion. The present study examined long-term behavioral and glial alterations in the basolateral amygdala (BLA) at 15 weeks after OBX in male Wistar rats (Rattus norvegicus). Animals were assigned to two experimental cohorts. In the first, rats underwent OBX or sham surgery and remained undisturbed until assessment of exploratory behavior in the open-field test (OFT). In the second cohort, nociceptive sensitivity was evaluated weekly using mechanical and thermal assays. In the first cohort, OBX animals showed no significant changes in horizontal or vertical activity in the OFT but exhibited hypertrophic astrocytes in the BLA. In contrast, the nociceptive cohort developed persistent mechanical and cold allodynia without evidence of mechanical hyperalgesia. An increased number of astrocytes and the hypotrophic microglial morphology in the BLA accompanied these sensory alterations. Together, these findings indicate that OBX produces long-lasting glial remodeling and chronic pain–like states, supporting the neurobiological link between depression and pain comorbidity. Moreover, not all behavioral alterations occur at the same time as observed in depression.