Functional Role of Intracellular Calcium Receptor Inositol 1,4,5-Trisphosphate Type 1 in Rat Hippocampus after Neonatal Anoxia

Abstract

Anoxia is one of the most prevalent causes of neonatal morbidity and mortality, especially in preterm neonates, constituting an important public health problem due to permanent neurological sequelae observed in patients. Oxygen deprivation triggers a series of simultaneous cascades, culminating in cell death mainly located in more vulnerable metabolic brain regions, such as the hippocampus. In the process of cell death by oxygen deprivation, cytosolic calcium plays crucial roles. Intracellular inositol 1,4,5-trisphosphate receptors (IP3Rs) are important regulators of cytosolic calcium levels, although the role of these receptors in neonatal anoxia is completely unknown. This study focused on the functional role of inositol 1,4,5-trisphosphate receptor type 1 (IP3R1) in rat hippocampus after neonatal anoxia. Quantitative real-time PCR revealed a decrease of IP3R1 gene expression 24 hours after neonatal anoxia. We detected that IP3R1 accumulates specially in CA1, and this spatial pattern did not change after neonatal anoxia. Interestingly, we observed that anoxia triggers translocation of IP3R1 to nucleus in hippocampal cells. We were able to observe that anoxia changes distribution of IP3R1 immunofluorescence signals, as revealed by cluster size analysis. We next examined the role of IP3R1 in the neuronal cell loss triggered by neonatal anoxia. Intrahippocampal injection of non-specific IP3R1 blocker 2-APB clearly reduced the number of Fluoro-Jade C and Tunel positive cells, revealing that activation of IP3R1 increases cell death after neonatal anoxia. Finally, we aimed to disclose mechanistics of IP3R1 in cell death. We were able to determine that blockade of IP3R1 did not reduced the distribution and pixel density of activated caspase 3-positive cells, indicating that the participation of IP3R1 in neuronal cell loss is not related to classical caspase-mediated apoptosis. In summary, this study may contribute to new perspectives in the investigation of neurodegenerative mechanisms triggered by oxygen deprivation.

Type 3 inositol 1,4,5-trisphosphate receptor has antiapoptotic and proliferative role in cancer cells

“…The question remains, what is the mechanism by which IP 3 R3 realized its anti-apoptotic effect. On contrary to IP 3 R3, the involvement of the IP 3 R1 in apoptosis induction in a variety of cells was shown in several papers 6,25 . The IP 3 R1 is involved in the mechanism of action of some potential chemotherapeutic agents, e.g., sulforaphane 6 , or melatonin 21 , partially through the increased expression of the IP 3 R1.…”

The ATF6β-calreticulin axis promotes neuronal survival under endoplasmic reticulum stress and excitotoxicity

“…To develop a KA injection model, male mice were anesthetized, and saline or KA (0.2 µg/µl, 0.5 µl in total; Sigma, St Louis, MO, USA) was injected unilaterally into the hippocampus (from Bregma: dorso-ventral, − 2.0; medio-lateral, − 2.4; anterior–posterior, − 1.8), as previously described 10 . In some cases, 2-APB (12 µM, 0.5 µl in total; FUJFILM Wako Pure Chemical Co., Osaka, Osaka, Japan) or salubrinal (1 mg/kg; Cayman Chemical, Ann Arbor, MI, USA) was co-injected with KA into the hippocampus, or intraperitoneally injected 30 min before KA administration, as previously described 2 , 35 , 36 . Mice were sacrificed at the indicated timepoints after KA injection, and brain samples were prepared for histological and biochemical analysis.…”

The ATF6β-Calreticulin Axis Promotes Neuronal Survival Under Endoplasmic Reticulum Stress and Excitotoxicity

“…To develop a KA injection model, male mice were anesthetized, and saline or KA (0.2 µg/µl, 0.5 µl in total; Sigma, St Louis, MO, USA) was injected unilaterally into the hippocampus (from Bregma: dorsoventral,-2.0; medio-lateral, -2.4; anterior-posterior, -1.8), as previously described 10 . In some cases, 2-APB (12 µM, 0.5 µl in total; FUJFILM Wako Pure Chemical Co., Osaka, Osaka, Japan) or salubrinal (1mg/kg; Cayman Chemical, Ann Arbor, MI, USA) was co-injected with KA into the hippocampus, or intraperitoneally injected 30 min before KA administration, as previously described 2,35,36 . Mice were sacrificed at the indicated timepoints after KA injection, and brain samples were prepared for histological and biochemical analysis.…”