Short-term Heat Exposure Promotes Hippocampal Neurogenesis via Activation of Angiotensin II Type 1 Receptor in Adult Rats. (10th August 2018)

• Record Type: Journal Article
• Authors: Koyama, Yuka; Mukuda, Takao; Hamasaki, Sawako; Nakane, Hironobu; Kaidoh, Toshiyuki
• Is Part Of: Neuroscience. Volume 385(2018)
• Page Start: 121
• Page End: 132
• Publication Date: 2018-08-10
• Subjects: AGT angiotensinogen -- Ang II angiotensin II -- AT1R Ang II type 1 receptor -- AT2R Ang II type 2 receptor -- BDNF brain-derived neurotrophic factor -- CONT control -- DCX doublecortin -- GFAP glial fibrillary acidic protein -- HEAT heat exposure -- PBS phosphate-buffered saline -- RAS renin–angiotensin system -- VEGF vascular endothelial growth factor; neurogenesis -- hippocampus -- short-term heat exposure -- angiotensin II type 1 receptor -- candesartan -- vascular endothelial growth factor; Neurochemistry -- Periodicals; Neurophysiology -- Periodicals; Neurology -- Periodicals; Neurochimie -- Périodiques; Neurophysiologie -- Périodiques; Neurochemistry; Neurophysiology; Electronic journals; Periodicals; Electronic journals; 612.8
• DOI: 10.1016/j.neuroscience.2018.05.045
• Languages: English
• ISSNs: 0306-4522

Abstract

Highlights: Short-term heat exposure increases doublecortin-positive newborn neuron numbers in adult rat hippocampal dentate gyrus. This stimulus also promotes expression of vascular endothelial growth factor in the hippocampus, probably in astrocytes. Treatment with candesartan, an angiotensin II type 1 receptor antagonist, cancels these effects to basal levels. Short-term heat exposure may promote adult neurogenesis via AT1R activation, possibly by enhanced VEGF expression. Abstract: Angiotensin II (Ang II) synthesized in response to body fluid loss caused by actions such as sweating and breathing is today considered as one of the essential factors for promoting hippocampal neurogenesis. Because heat stimuli, along with exercise, increase systemic levels of Ang II, the effects of short-term heat exposure on hippocampal neurogenesis were examined in adult male rats. When rats were exposed daily to a 1-h heat treatment (36.0 ± 0.1 °C) during a 7-d experimental period, the number of doublecortin-immunoreactive newborn cells in the hippocampal dentate gyrus was increased approximately 1.4-fold compared with that in controls that were exposed to a normothermic environment (25.0 ± 0.8 °C). No significant change was observed in the number of Ki-67-immunoreactive stem cells. Western blot and immunohistochemical analyses revealed an enhancement of vascular endothelial growth factor (VEGF) expression in hippocampal astrocytes following short-term heat exposure. These beneficial effects of short-term heat exposure were prevented when an antagonist for Ang II type 1 receptor (AT1R), candesartan, was given orally. These results indicate that short-term heat exposure enhances adult neurogenesis via activation of AT1R in the hippocampal dentate gyrus, in which VEGF may participate by promoting cell proliferation and/or newborn neuron survival.