Motopsin deficiency imparts partial insensitivity to doxorubicin-induced hippocampal impairments in adult mice

Neuroprotective effect of empagliflozin against doxorubicin-induced chemobrain in rats: Interplay between SIRT-1/MuRF-1/PARP-1/NLRP3 signaling pathways and enhanced expression of miRNA-34a and LncRNA HOTAIR

Chemobrain, a challenging side effect of doxorubicin (DOX)-based chemotherapy, impairs cognitive abilities in cancer survivors. DOX triggers chemobrain via oxidative stress, leading to inflammation and apoptosis. Empagliflozin (EMPA), a sodium glucose co-transporter-2 inhibitor, demonstrated neuroprotective effects by reducing reactive oxygen species (ROS) and inflammation, but its protective mechanisms against DOX-induced chemobrain is not fully known. Thus, this study aimed to investigate EMPA's neuroprotective effects on DOX-induced chemobrain in rats and to uncover the underlying protective mechanisms. Fifty male Wistar rats were divided into control, EMPA, DOX (2 mg/kg, IP, once/week for 4 weeks), and two treated groups (DOX+ EMPA 5 and 10 mg/kg/day, PO, for 4 weeks). Behavioral tests showed improved memory, motor performance, and reduced anxiety in EMPA-treated groups compared to DOX, with superior results at the higher dose. Histopathological analysis revealed increased intact neurons in the cortex and hippocampus in EMPA-treated groups, with 346.4 % increase in CA3 (p < 0.0001), 19.1 % in dentate gyrus (p = 0.0006), and 362.6 % in cortex (p < 0.0001) in the high-dose EMPA group. Biochemical investigations of the high-dose EMPA group revealed significant decreases in inflammatory and apoptotic markers (JNK/PARP-1/NLRP3/MuRF-1/FOXO-1), increased SIRT-1 protein expression by 389.9 % (p < 0.0001), and reduced miRNA-34a and LncRNA HOTAIR gene expression (50.4 % and 53.4 % respectively, p < 0.0001) relative to DOX group. Conclusively, EMPA demonstrated superior behavioral and histopathological outcomes particularly at higher dose, positioning it as a promising neuroprotective candidate against DOX-induced chemobrain, possibly through modulating SIRT-1, NF-κb, NLRP3, and oxidative stress pathways.

Overexpression of Motopsin, an Extracellular Serine Protease Related to Intellectual Disability, Promotes Adult Neurogenesis and Neuronal Responsiveness in the Dentate Gyrus

Motopsin, a serine protease encoded by PRSS12, is secreted by neuronal cells into the synaptic clefts in an activity-dependent manner, where it induces synaptogenesis by modulating Na+/K+-ATPase activity. In humans, motopsin deficiency leads to severe intellectual disability and, in mice, it disturbs spatial memory and social behavior. In this study, we investigated mice that overexpressed motopsin in the forebrain using the Tet-Off system (DTG-OE mice). The elevated agrin cleavage or the reduced Na+/K+-ATPase activity was not detected. However, motopsin overexpression led to a reduction in spine density in hippocampal CA1 basal dendrites. While motopsin overexpression decreased the ratio of mature mushroom spines in the DG, it increased the ratio of immature thin spines in CA1 apical dendrites. Female DTG-OE mice showed elevated locomotor activity in their home cages. DTG-OE mice showed aberrant behaviors, such as delayed latency to the target hole in the Barnes maze test and prolonged duration of sniffing objects in the novel object recognition test (NOR), although they retained memory comparable to that of TRE-motopsin littermates, which normally express motopsin. After NOR, c-Fos-positive cells increased in the dentate gyrus (DG) of DTG-OE mice compared with that of DTG-SO littermates, in which motopsin overexpression was suppressed by the administration of doxycycline, and TRE-motopsin littermates. Notably, the numbers of doublecortin- and 5-bromo-2'-deoxyuridine-labeled cells significantly increased in the DG of DTG-OE mice, suggesting increased adult neurogenesis. Importantly, our results revealed a new function in addition to modulating neuronal responsiveness and spine morphology in the DG: the regulation of neurogenesis.