Background Sex differences in experimental stroke outcomes are well documented, such that adult males have a greater infarct volume, increased stroke-induced mortality, and more severe sensory-motor impairment. Based on recent evidence that the gut is an early responder to stroke, the present study tested the hypothesis that sex differences in stroke severity will be accompanied by rapid and greater permeability of the gut-blood barrier and gut dysbiosis in males as compared to females. Method Male and female Sprague-Dawley rats (5–7 months of age) were subject to endothelin (ET)-1-induced middle cerebral artery occlusion (MCAo). Sensory-motor tests were conducted pre- and 2 days after MCAo. Gut permeability was assessed in serum samples using biomarkers of gut permeability as well as functional assays using size-graded dextrans. Histological analysis of the gut was performed with H&E staining, periodic acid-Schiff for mucus, and immunohistochemistry for the tight junction protein, ZO-1. Fecal samples obtained pre- and post-stroke were analyzed for bacterial taxa and short-chain fatty acids (SCFAs). Results After stroke, males displayed greater mortality, worse sensory-motor deficit, and higher serum levels of proinflammatory cytokines IL-17A, MCP-1, and IL-5 as compared to females. MCAo-induced gut permeability was rapid and severe in males as indicated by dextran extravasation from the gut to the blood in the hyperacute (< 2 h) and early acute (2 days) phase of stroke. This was accompanied by dysmorphology of the gut villi and dysregulation of the tight junction protein ZO-1 in the acute phase. Fecal 16s sequencing showed no differences in bacterial diversity in the acute phase of stroke. Predictive modeling indicated that markers of gut permeability were associated with acute sensory-motor impairment and infarct volume. Conclusions These data show that extensive leakiness of the gut barrier is associated with severe post-stroke disability and suggest that reinforcing this barrier may improve stroke outcomes.

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Cognitive impairment and memory loss are commonly seen after stroke and a third of patients will develop signs of dementia a year after stroke. Despite a large number of studies on the beneficial effects of neuroprotectants, few studies have examined the effects of these compounds/interventions on long-term cognitive impairment. Our previous work showed that the microRNA mir363-3p reduced infarct volume and sensory-motor impairment in the acute stage of stroke in middle-aged females but not males. Thus, the present study determined the impact of mir363-3p treatment on stroke-induced cognitive impairment in middle-aged females. Sprague–Dawley female rats (12 months of age) were subjected to middle cerebral artery occlusion (MCAo; or sham surgery) and injected (iv) with mir363-3p mimic (MCAo + mir363-3p) or scrambled oligos (MCAo + scrambled) 4 h later. Sensory-motor performance was assessed in the acute phase (2–5 days after stroke), while all other behaviors were tested 6 months after MCAo (18 months of age). Cognitive function was assessed by the novel object recognition test (declarative memory) and the Barnes maze (spatial memory). The MCAo + scrambled group showed reduced preference for a novel object after the stroke and poor learning in the spatial memory task. In contrast, mir363-3p treated animals were similar to either their baseline performance or to the sham group. Histological analysis showed significant deterioration of specific white matter tracts due to stroke, which was attenuated in mir363-3p treated animals. The present data builds on our previous finding to show that a neuroprotectant can abrogate the long-term effects of stroke.

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During obesity, diabetes and hypertension inevitably coexist and cause innumerable health disparities. In the obesity, diabetes, and hypertension triad (ODHT), deregulation of glucose and NaCl homeostasis, respectively, causes diabetes and hypertension. In the mammalian intestine, glucose is primarily absorbed by Naglucose cotransport 1 (SGLT1) and coupled NaCl by the dual operation of Na‐H exchange 3 (NHE3) and Cl‐HCO3 [down‐regulated in adenoma (DRA) or putative anion transporter 1 (PAT1)] exchange in the brush border membrane (BBM) of villus cells. The basolateral membrane (BLM) Na/K‐ATPase provides the favorable transcellular Na gradient for BBM SGLT1 and NHE3. How these multiple, distinct transport processes may be affected in ODHT is unclear. Here, we show the novel and broad regulation by Na/K‐ATPase of glucose and NaCl absorption in ODHT in multiple species (mice, rats, and humans). In vivo, during obesity inhibition of villus‐cell BLM, Na/K‐ATPase led to compensatory stimulation of BBM SGLT1 and DRA or PAT1, whereas NHE3 was unaffected. Supporting this new cellular adaptive mechanism, direct silencing of BLM Na/K‐ATPase in intestinal epithelial cells resulted in selective stimulation of BBM SGLT1 and DRA or PAT1 but not NHE3. These changes will lead to an increase in glucose absorption, maintenance of traditional coupled NaCl absorption, and a de novo increase in NaCl absorption from the novel coupling of stimulated SGLT1 with DRA or PAT1. Thus, these novel observations provide the pathophysiologic basis for the deregulation of glucose and NaCl homeostasis of diabetes and hypertension, respectively, during obesity. These observations may lead to more efficacious treatment for obesity‐associated diabetes and hypertension.—Palaniappan, B., Arthur, S., Sundaram, V. L., Butts, M., Sundaram, S., Mani, K., Singh, S., Nepal, N., Sundaram, U. Inhibition of intestinal villus cell Na/K‐ATPase mediates altered glucose and NaCl absorption in obesity‐associated diabetes and hypertension. FASEB J. 33, 9323–9333 (2019). http://www.fasebj.org

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Sex differences in experimental stroke are well documented, such that adult males show worse outcomes compared to adult females, including greater infarct volume, increased stroke-induced mortality and more severe sensory-motor impairment. Based on recent evidence that gut dysbiosis may be an early response to stroke, the present study tested the hypothesis that in the acute phase, stroke will result in greater gut dysbiosis and greater permeability of the gut blood barrier in males as compared to females. Male and female Sprague Dawley rats (5-7 months of age) were subject to endothelin-1-induced middle cerebral artery occlusion (MCAo). Fecal samples, blood draws and sensory motor tests were collected/conducted pre and 2d after MCAo. Fecal samples were subject to 16s sequencing. Serum samples were subject to gas chromatography for short chain fatty acid (SCFA) analysis. Gut permeability was assessed by histology, biochemical markers in serum and functional assays using oral dextran gavage. We confirmed stroke-induced sex differences, including increased mortality and more severe sensory motor deficit in males as compared to age-matched female rats. Fecal 16s sequencing showed greater bacterial diversity in females at baseline (pre stroke) while 2 days after stroke, these measures were similar between the sexes. Fecal levels of SCFAs, which are usually beneficial, were higher in males. In contrast, MCAo-induced gut permeability was much worse in males as compared to females. Male rats had a decreased villus length to crypt length ratio, higher levels of biochemical gut permeability markers in serum and higher levels of fluorescent-labeled dextrans following oral gavage in serum. Additionally, males had higher serum levels of proinflammatory cytokines IL-17A, MCP-1, IL-5 and EGF compared to females after stroke. Collectively, these results indicate that the worse stroke outcomes seen in males is associated with increased gut permeability in this group. These data suggest that therapeutics that target the gut epithelium in order to reinforce the gut-blood barrier post stroke may be an effective intervention especially in populations such as the elderly or those with co-morbid conditions who have already been shown to have more permeable barriers.