Sex related differences in cognitive deficits: Disrupted Arc/Arg3.1 signaling in an HIV model.

Combined and highly active anti-retroviral therapies (cART) have transitioned HIV into a more chronic disease. Roughly half of people living with HIV (PLWH) still experience neurocognitive disorders, albeit less severely than in the pre-cART era. Sex-related effects on memory/cognition remain understudied, although the percentage of PLWH that are female has increased. We utilized a transgenic mouse model of HIV that conditionally expresses HIV-1 Tat in the CNS to examine cognitive behaviors and the expression of biomarkers related to learning and memory in both sexes. Tat+ males exhibited deficits in spatial learning/memory and object recognition, while Tat+ females showed enhanced fear memory. We investigated the involvement of activity-regulated cytoskeleton-associated protein (Arc), which is induced by novel experience related to learning/memory. We observed hippocampal Arc induction following foot shock in Tat+ females but not Tat+ males. Hippocampal levels of Arc, amyloid β (Aβ) monomers/oligomers and pCREB were altered in a sex-specific manner. CREB activity, which is highly associated with Arc induction, was reduced only in Tat+ males. Tat exposure also decreased Arc expression in cultured human neurons. Thus, HIV-1 Tat effects on CREB/Arc signaling may differ between sexes, contributing to differences in cognitive deficits observed here and in PLWH.