Hyperthermic induction of the 27-kDa heat shock protein (Hsp27) in neuroglia and neurons of the rat central nervous system

Abstract

The 27-kDa heat shock protein (Hsp27) is constitutively expressed in many neurons of the brainstem and spinal cord, is strongly induced in glial cells in response to ischemia, seizures, or spreading depression, and is selectively induced in neurons after axotomy. Here, the expression of Hsp27 was examined in brains of adult rats from 1.5 hours to 6 days after brief hyperthermic stress (core body temperature of 42 degrees C for 15 minutes). Twenty-four hours following hyperthermia, Western blot analysis showed that Hsp27 was elevated in the cerebral cortex, hippocampus, cerebellum, and brainstem. Immunohistochemistry for Hsp27 revealed a time-dependent, but transient, increase in the level of Hsp27 immunoreactivity (Hsp27 IR) in neuroglia and neurons. Hsp27 IR was detected in astrocytes throughout the brain and in Bergmann glia of the cerebellum from 3 hours to 6 days following heat shock. Peak levels were apparent at 24 hours, gradually declining thereafter. In addition, increases in Hsp27 IR were detected in the ependyma and choroid plexus. Hyperthermia induced Hsp27 IR in neurons of the subfornical organ and the area postrema within 3 hours and reached a maximum by 24 hours with a return to control levels 4-6 days after hyperthermia. Specific populations of hypothalamic neurons also showed Hsp27 IR after hyperthermia. These results demonstrate that hyperthermia induces transient expression of Hsp27 in several types of neuroglia and specific populations of neurons. The pattern of induced Hsp27 IR suggests that some of the activated cells are involved in physiological responses related to body fluid homeostasis and temperature regulation.

Heat shock treatment protects against angiotensin II–induced hypertension and inflammation in aorta

“…After hyperthermic treatment, select neurons of the hippocampal formation, of the hypothalamus, such as paraventricular nucleus and dorsomedial hypothalamic nucleus, and of the circumventricular organs, such as subfornical organ and area postrema, expressed high levels of Hsp27. This suggests that some Hsp27-positive cells are involved in physiological responses to body fluid homeostasis (Krueger-Naug et al 2000). In addition, these regions of the brain are involved in the modulation of blood pressure by Ang II (Lenkei et al 1997).…”

Administration of brain-derived neurotrophic factor suppresses the expression of heat shock protein 27 in rat retinal ganglion cells following axotomy

“…Sections were incubated with phosphate-buffered saline (PBS) containing 0.1% Triton-X (PBS-X) and 10% goat serum for 1 h at room temperature. Primary rabbit polyclonal antibody specific for the murine 25 kDa heat shock protein, Hsp25, and the homologous rat Hsp27 (Plumier et al, 1997c;Krueger-Naug et al, 2000, 2002aArmstrong et al, 2001; StressGen Biotechnologies Corporation, Victoria, BC, Canada) was diluted 1:1000 in PBS-X with 2% goat serum and incubated overnight at 4°C. After three 10-min rinses, sections were incubated for 3 h in PBS (no Triton-X) containing Alexa goat anti-rabbit 546 (1:500; Molecular Probes, Eugene, OR, USA).…”

“…In the peripheral nervous system, sciatic nerve injury and vagotomy have resulted in the induction and prolonged expression of Hsp27 in the affected neurons (Costigan et al, 1998;Hopkins et al, 1998;Lewis et al, 1999). Hyperthermia causes the induction of Hsp27 primarily in astroglia throughout the CNS; in addition, hyperthermia results in Hsp27 expression in specific nuclei associated with fluid homeostasis and thermoregulation (Krueger-Naug et al, 2000). With excitotoxic injury such as kainic acid-induced status epilepticus (Plumier et al, 1996), and potassium chloride-induced cortical spreading depression (Plumier et al, 1997b), Hsp27 is detected primarily in astrocytes.…”

Trimethylamine oxide suppresses stress-induced alteration of organic anion transport in choroid plexus

“…For example, transient ischemia and subsequent reperfusion of rat CP markedly attenuate Na + /K + -ATPase activity and the capacity for glutamate accumulation (Ennis and Keep, 2006;Johanson et al, 2000;Palm et al, 1995). However, this brain barrier mounts a cellular stress response (Blake et al, 1990;Brown, 1991;Krueger-Naug et al, 2000), which in other tissues can be generally protective against physicochemical stressors such as ischemia, hyperthermia, oxidants or heavy metals and may ameliorate loss of function in CP.…”