title: β-amyloid infusion into lateral ventricle alters behavioral thermoregulation and attenuates acquired heat tolerance in rats.
abstract: We investigated behavioral thermoregulatory function and acquired heat tolerance of β-amyloid (Aβ)-infused rats. Male Wistar rats were anesthetized and implanted in the intraperitoneal cavity with a temperature transmitter. Aβ peptide (4.9-5.5 nmol) was dissolved in a solvent of 35% acetonitrile and 0.1% trifluoroacetic acid (pH 2.0). The solvent was used as the vehicle. An osmotic pump contained 234 ± 13.9 μl of Aβ solution was subcutaneously implanted in the back and was cannulated into the left cerebral ventricle. Moreover, 0.5 µg of AlCl3 was injected into the right cerebral ventricle with a micro syringe pump (Aβ-infused rats). The solvent-infused rats were used as control rats (CN rats). After 2 weeks, rats were placed in a thermal gradient and their intra-abdominal temperature (T ab ) and their ambient temperatures (T a ) selected (T s ) were measured for 3 consecutive days. In an additional study, rats were kept at a T a of 32°C for 4 weeks to attain heat acclimation. Then, rats were subjected to a heat tolerance test, i.e. they were exposed to a T a of 36°C for 160 min. Although there were clear day-night variations of T s and T ab in CN rats, patterns were significantly abolished in Aβ-infused rats. Moreover, heat tolerance obtained by heat acclimation was attenuated in Aβ-infused rats. These results suggest that Aβ-infusion in the lateral ventricle modifies behavioral thermoregulation and lowers an ability to acclimate to heat in rats.
authors.affiliation: Department of Environmental Physiology; Faculty of Medicine; Shimane University ; Izumo, Shimane, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Matsuzaki
authors.affiliation: Department of Environmental Physiology; Faculty of Medicine; Shimane University ; Izumo, Shimane, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Katakura
authors.affiliation: Department of Environmental Physiology; Faculty of Medicine; Shimane University; Izumo, Shimane, Japan; Department of Physiology; Graduate School of Medical Science; Kanazawa University; Kanazawa, Ishikawa, Japan.
authors.forename: Naotoshi
authors.initials: N
authors.lastname: Sugimoto
authors.affiliation: Department of Environmental Physiology; Faculty of Medicine; Shimane University ; Izumo, Shimane, Japan.
authors.forename: Toshiko
authors.initials: T
authors.lastname: Hara
authors.affiliation: Department of Environmental Physiology; Faculty of Medicine; Shimane University ; Izumo, Shimane, Japan.
authors.forename: Michio
authors.initials: M
authors.lastname: Hashimoto
authors.affiliation: Department of Environmental Physiology; Faculty of Medicine; Shimane University ; Izumo, Shimane, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Shido
keywords: behavioral thermoregulation; heat acclimation; hypothalamus; rats; β-amyloid