The influence of the prolactin/vasoinhibin axis on post-stroke lesion volume, astrogliosis, and survival.

Ischemic stroke is a significant global health issue, ranking fifth among all causes of death and a leading cause of serious long-term disability. Ischemic stroke leads to severe outcomes, including permanent brain damage and neuronal dysfunction. Therefore, decreasing and preventing neuronal injuries caused by stroke has been the focus of therapeutic research. In recent years, many studies have shown that fluctuations in hormonal levels influence the prognosis of ischemic stroke. Thus, it is relevant to understand the role of hormones in the pathophysiological mechanisms of ischemic stroke for preventing and treating this health issue. Here, we investigate the contribution of the prolactin/vasoinhibin axis, an endocrine system regulating blood vessel growth, immune processes, and neuronal survival, to the pathophysiology of ischemic stroke. Male mice with brain overexpression of prolactin or vasoinhibin by adeno-associated virus (AAV) intracerebroventricular injection or lacking the prolactin receptor (Prlr^-/-) were exposed to transient middle cerebral artery occlusion (tMCAO) for 45 min followed by 48 h of reperfusion. Overexpression of vasoinhibin or the absence of the prolactin receptor led to an increased lesion volume and decreased survival rates in mice following tMCAO, whereas overexpression of prolactin had no effect. In addition, astrocytic distribution in the penumbra was altered, glial fibrillary acidic protein and S100b mRNA expressions were reduced, and interleukin-6 mRNA expression increased in the ischemic hemisphere of mice overexpressing vasoinhibin. Of note, prolactin receptor-null mice (Prlr^-/-) showed a marked increase in serum vasoinhibin levels. Furthermore, vasoinhibin decreased astrocyte numbers in mixed hippocampal neuron-glia cultures. These observations suggest that increased vasoinhibin levels may hinder astrocytes' protective reactivity. Overall, this study suggests the involvement of the prolactin/vasoinhibin axis in the pathophysiology of ischemic stroke-induced brain injury and provides insights into the impact of its dysregulation on astrocyte reactivity and lesion size. Understanding these mechanisms could help develop therapeutic interventions in ischemic stroke and other related neurological disorders.