Deficits in ultrasonic vocalization development and production following neonatal hypoxic ischemic insult

Neonatal hypoxic ischemia encephalopathy (HIE) leads to major deficits in language development. While clinically there is a known correlation in the degree of HIE injury and subsequent language disability, there are no treatments beyond speech and language therapy; therefore, experimental studies with a HIE animal model to test new interventions and therapeutics are warranted. Neonatal rodents normally ultrasonically vocalize at postnatal day 7 (PND 7) to PND 14 in response to removal from their mothers. At 6-8 weeks of age juvenile male rodents ultrasonically vocalize in response to exposure to a mature female mouse. Changes in ultrasonic vocalization (USV) production after neonatal brain injury, such ashypoxic ischemia (HI), have not been studied. This study examines the acute and long-term ultrasonic vocalization ability of mice after HI at PND 10. Pups were subjected to HI, sham, or naïve conditions; where in HI and sham surgeries the right common carotid artery was exposed, in the HI this artery was double ligated. The HI and sham pups were then exposed to60minof hypoxia. Naïve pups did not undergo surgery and were subjected to60minof room air. At 3 days following surgery, HI and sham pups vocalize less than nonsurgical naïve controls; yet "juvenile" mice of 6-8 weeks old that underwent HI at PND 10 vocalize less than sham and naïve mice. We conclude that HI injury has significant impact on later adult vocalization.

Knockout of vascular early response gene worsens chronic stroke outcomes in neonatal mice

Vascular early response gene (Verge) is a novel immediate early gene that is highly expressed during developmental angiogenesis and after ischemic insults in adult brain. However, the role of Verge after neonatal injury is not known. In the present study, we investigated the hypothesis that Verge contributes to vascular remodeling and tissue repair after neonatal ischemic injury. The Rice-Vanucci model (RVM) was employed to induce neonatal stroke in both Verge knockout (KO) and wild-type (WT) postnatal day 10 (P10) mice. Histological and behavioral outcomes at acute (24h), subacute (7 days) and chronic (30 days) phases were evaluated. Angiogenesis, neurogenesis, and glial scar formation were also examined in the ischemic brain. No significant differences in outcomes were found between WT and Verge mice at 24h or 7 days after stroke. However genetic deletion of Verge led to pronounced cystic cavitation, decreased angiogenensis and glial scar formation in the ischemic hemisphere compared to WT mice at 30 days. Verge KO mice also had significantly worse functional outcomes at 30 days which was accompanied by decreased neurogenesis and angiogenesis in the ischemic hemisphere. Our study suggests that Verge plays an important role in the induction of neurogenesis and angiogenesis after ischemia, contributes to improved tissue repair, and enhances chronic functional recovery.

Sex, stroke, and inflammation: the potential for estrogen-mediated immunoprotection in stroke

Stroke is the third leading cause of death and the primary cause of disability in the developed world. Experimental and clinical data indicate that stroke is a sexually dimorphic disease, with males demonstrating an enhanced intrinsic sensitivity to ischemic damage throughout most of their lifespan. The neuroprotective role of estrogen in the female brain is well established, however, estrogen exposure can also be deleterious, especially in older women. The mechanisms for this remain unclear. Our current understanding is based on studies examining estrogen as it relates to neuronal injury, yet cerebral ischemia also induces a robust sterile inflammatory response involving local and systemic immune cells. Despite the potent anti-inflammatory effects of estrogen, few studies have investigated the contribution of estrogen to sex differences in the inflammatory response to stroke. This review examines the potential role for estrogen-mediated immunoprotection in ischemic injury.