Endoplasmic reticulum stress induces apoptosis of arginine vasopressin neurons in central diabetes insipidus via PI3K/Akt pathway.

AIMS: Central diabetes insipidus (CDI), a typical complication caused by pituitary stalk injury, often occurs after surgery, trauma, or tumor compression around hypothalamic structures such as the pituitary stalk and optic chiasma. CDI is linked to decreased arginine vasopressin (AVP) neurons in the hypothalamic supraoptic nucleus and paraventricular nucleus, along with a deficit in circulating AVP and oxytocin. However, little has been elucidated about the changes in AVP neurons in CDI. Hence, our study was designed to understand the role of several pathophysiologic changes such as endoplasmic reticulum (ER) stress and apoptosis of AVP neurons in CDI. METHODS: In a novel pituitary stalk electric lesion (PEL) model to mimic CDI, immunofluorescence and immunoblotting were used to understand the underlying regulatory mechanisms. RESULTS: We reported that in CDI condition, generated by PEL, ER stress induced apoptosis of AVP neurons via activation of the PI3K/Akt and ERK pathways. Furthermore, application of N-acetylcysteine protected hypothalamic AVP neurons from ER stress-induced apoptosis through blocking the PI3K/Akt and ERK pathways. CONCLUSION: Our findings showed that AVP neurons underwent apoptosis induced by ER stress, and ER stress might play a vital role in CDI condition through the PI3K/Akt and ERK pathways.

[An improved method for stereotactic location of the supraoptic nucleus with oblique stereotactic puncture in rats].

OBJECTIVE: To establish an improved method for stereotactic location of the supraoptic nucleus in rats. METHODS: Twenty-four SD rats were randomly divided into experimental group (12 rats) and control group (12 rats) for oblique (20° to the left) stereotactic puncture (OSP group) and vertical stereotactic puncture (VSP group), respectively, both targeting the supraoptic nucleus (SON). The surgical data and postoperative (within 24) mortality of the rats were compared between the two groups. RESULTS: The nucleus locating time was longer in OSP group than in VSP group (59.55∓3.64s vs 27.44∓2.18 s, P=0.000), and the postoperative mortality rate of the rats did not differ significantly between the groups (0 vs 44.4%, P=0.082). In OSP group, compared with VSP group, the procedure was associated with a lowered rupture rate of the superior sagittal sinus (11.1% vs 88.9%, P=0.003), a shortened hemostatic time after craniotomy (52.89∓24.05 s vs 157.445 ime a s, P=0.000) and after puncture (24.33 reas 45 s vs 133.89∓28.81 s, P=0.000), and also a shortened operation time (178.89 on tims vs 362.44 timees, P=0.000). CONCLUSION: The improved method for locating supraoptic nucleus in rats is convenient, stable and reproducible, and helps to avoid important blood vessels and specific nuclei according to the needs of different experiments and allows the operators to choose different surgical paths.

The purine receptor P2X7R regulates the release of pro-inflammatory cytokines in human craniopharyngioma.

Craniopharyngiomas (CPs) are usually benign, non-metastasizing embryonic malformations originating from the sellar area. They are, however, locally invasive and generate adherent interfaces with the surrounding brain parenchyma. Previous studies have shown the tumor microenvironment is characterized by a local abundance of adenosine triphosphate (ATP), infiltration of leukocytes and elevated levels of pro-inflammatory cytokines that are thought to be responsible, at least in part, for the local invasion. Here, we examine whether ATP, via the P2X7R, participates in the regulation of cytokine expression in CPs. The expression of P2X7R and pro-inflammatory cytokines were measured at the RNA and protein levels both in tumor samples and in primary cultured tumor cells. Furthermore, cytokine modulation was measured after manipulating P2X7R in cultured tumor cells by siRNA-mediated knockdown, as well as pharmacologically by using selective agonists and antagonists. The following results were observed. A number of cytokines, in particular IL-6, IL-8 and MCP-1, were elevated in patient plasma, tumor tissue and cultured tumor cells. P2X7R was expressed in tumor tissue as well as in cultured tumor cells. RNA expression as measured in 48 resected tumors was positively correlated with the RNA levels of IL-6, IL-8 and MCP-1 in tumors. Furthermore, knockdown of P2X7R in primary tumor cultures reduced, and stimulation of P2XR7 by a specific agonist enhanced the expression of these cytokines. This latter stimulation involved a Ca2+-dependent mechanism and could be counteracted by the addition of an antagonist. In conclusion, the results suggest that P2X7R may promote IL-6, IL-8 and MCP-1 production and secretion and contribute to the invasion and adhesion of CPs to the surrounding tissue.