Upregulated Expression of SSTR3 is Involved in Neuronal Apoptosis After Intracerebral Hemorrhage in Adult Rats

Somatostatin which is a multifunctional growth hormone inhibitory neuropeptide shows diverse physiological effects, such as neurotransmission, cell growth, apoptosis, and endocrine signaling as well as exerts inhibitory effects on hormonal products and other secretory proteins. SSTR3 is a member of superfamily of somatostatin receptors (SSTR), which are G-protein-coupled plasma membrane receptors. Previous studies proved that SSTR3 regulates antiproliferative signaling and apoptosis in several cells. Here, we explored a potential role of SSTR3 in the regulation of neuronal apoptosis in the course of intracerebral hemorrhage (ICH). An ICH rat model was established and assessed by behavioral tests. We found SSTR3 was significantly upregulated surrounding the hematoma after ICH by Western blot and immunohistochemistry. Double immunofluorescence-manifested SSTR3 was strikingly increased in neurons, not astrocytes or microglia. Moreover, increasing SSTR3 level was found to be accompanied by the upregulation of p53, Bax, and active caspase-3 in vivo and in vitro studies. Furthermore, we detected that neuronal apoptosis marker active caspase-3 was co-localized with SSTR3 suggesting its potential role in neuronal apoptosis. In addition, in vitro study, revealed that SSTR3 knockdown specifically resulted in reducing neuronal apoptosis in PC12 cells, which further indicated that SSTR3 might exert its pro-apoptotic function on neuronal apoptosis. All our findings suggested that upregulated SSTR3 may be involved in neuronal apoptosis after ICH.