17β-estradiol pretreatment reduces ca1sector cell death and the spontaneous hyperthermia that follows forebrain ischemia in the gerbil

doi:10.1016/j.neuroscience.2004.07.037

Neuroscience

Volume 129, Issue 1, 2004, Pages 187-193

https://doi.org/10.1016/j.neuroscience.2004.07.037 Get rights and content

Abstract

Pretreatment with 17β-estradiol attenuates ischemia-induced hippocampal cornu ammonis 1 (CA1) neuronal death. We assessed whether this is mediated through prevention of hyperthermia that normally follows ischemia in gerbils. Male gerbils were given sustained-released 17β-estradiol pellets or sham operation. Later, a guide cannula was implanted for brain temperature measurement and some were implanted with core temperature telemetry probes. Gerbils were subjected to either 5 min bilateral carotid artery occlusion or sham procedures 2 weeks after pellet surgery. Brain temperature was normothermic during surgery in all cases. In experiment 1, only core temperature was measured afterward in untreated and estrogen-treated gerbils. In experiment 2, postischemic core temperature was measured in untreated and two estrogen-treated ischemic groups, one of which had their postischemic temperature increased, via infrared lamp, to mimic the untreated group. Habituation was assessed on days 5 and 6. Hyperthermia, like that which occurs spontaneously, was forced on untreated and estrogen-treated ischemic animals in the third experiment, where brain temperature was measured. CA1 cell counts were assessed after a 7-day survival. A fourth experiment measured brain and core temperature simultaneously in normal gerbils during heating with an infrared lamp. Estrogen did not affect core temperature of non-ischemic gerbils whereas spontaneous postischemic hyperthermia was blocked. Estrogen reduced cell death and provided behavioral protection when gerbils regulated their own core temperature, but not when core hyperthermia was enforced. Conversely, estrogen reduced cell death in gerbils that had their brain temperature elevated. Experiment 4 showed that the brain becomes overheated (by approximately 1 °C) when core temperature is elevated. Accordingly, estrogen likely failed to reduce CA1 injury in experiment 2, when core hyperthermia was enforced, because of overheating the brain. In conclusion, estrogen reduces CA1 cell death by mechanisms other than preventing hyperthermia. Our results also suggest that future studies regulate brain instead of body temperature.

Section snippets

Animals

All procedures in this study were in accordance with the Canadian Council on Animal Care guidelines as well as international standards, and were approved by a local animal care committee. Efforts were made to minimize animal suffering and to limit the number of animals required.In total, 102 adult male (approximately 75 g on the first surgery day) Mongolian gerbils were used. In experiment 1, these animals were obtained from Charles River (Montreal, QC, Canada) and in experiments 2, 3 and 4

Experiment 1

Baseline T_core (24 h average on day prior to ISC/sham operation) ranged from 37.3 to 37.4 °C (Group effect: P=0.651). The first 8 h of T_core following ISC/sham operation (Fig. 1A) were averaged and analyzed by ANOVA (Group effect: P<0.001). During this time the SHAM-E2 (37.2±0.1) and SHAM-NT (37.2±0.1) were not significantly different (P=0.828). Spontaneous hyperthermia occurred in the ISC-NT group (38.1±0.1; P<0.001 versus combined SHAM group: 37.2±0.1). The ISC-E2 group (37.3±0.1) was not

Conclusions

The use of 17β-estradiol, starting 2 weeks prior to ISC, significantly reduced CA1 cell death and concomitant functional abnormalities, as previously found (Hurn et al., 1995; Sudo et al., 1997; Jover et al., 2002; McCullough and Hurn, 2003; Shughrue and Merchenthaler, 2003). Importantly, estrogen blocks the spontaneous postischemic T_core hyperthermia. Our second experiment suggests that estrogen's neuroprotective effect is solely due to preventing spontaneous hyperthermia because maintenance

Acknowledgments

Research supported by the Canadian Stroke Network. F.C. is the recipient of an Alberta Heritage Foundation for Medical Research medical scholar award. D.L.C. is supported by a summer studentship from the Canadian Stroke Network.

References (36)

F. Colbourne et al.
Characterization of postischemic behavioral deficits in gerbils with and without hypothermic neuroprotection
Brain Res
(1998)
D. Corbett et al.
MK-801 reduces cerebral ischemic injury by inducing hypothermia
Brain Res
(1990)
S. DeBow et al.
Brain temperature measurement in awake and freely moving rodents
Methods
(2003)
R.R. Freedman et al.
Estrogen raises the sweating threshold in postmenopausal women with hot flashes
Fertil Steril
(2002)
Z. He et al.
Proestrus levels of estradiol during transient global cerebral ischemia improves the histological outcome of the hippocampal CA1 region: perfusion-dependent and-independent mechanisms
J Neurol Sci
(2002)
T. Kirino
Delayed neuronal death in the gerbil hippocampus following ischemia
Brain Res
(1982)
L.D. McCullough et al.
Estrogen and ischemic neuroprotection: an integrated view
Trends Endocrinol Metab
(2003)
H. Memezawa et al.
Hyperthermia nullifies the ameliorating effect of dizocilpine maleate (MK-801) in focal cerebral ischemia
Brain Res
(1995)
J. Reith et al.
Body temperature in acute stroke: relation to stroke severity, infarct size, mortality, and outcome
Lancet
(1996)
P.J. Shughrue et al.
Estrogen prevents the loss of CA1 hippocampal neurons in gerbils after ischemic injury
Neuroscience
(2003)

F.Z. Stanczyk et al.

Limitations of direct estradiol and testosterone immunoassay kits

Steroids

(2003)

S. Sudo et al.

Beta-estradiol protects hippocampal CA1 neurons against transient forebrain ischemia in gerbil

Neurosci Res

(1997)

I.V. Tataryn et al.

Postmenopausal hot flushes: a disorder of thermoregulation

Maturitas

(1980)

Q. Zhao et al.

Hyperthermia complicates middle cerebral artery occlusion induced by an intraluminal filament

Brain Res

(1994)

R.C. Baena et al.

Hyperthermia delayed by 24 hours aggravates neuronal damage in rat hippocampus following global ischemia

Neurology

(1997)

E.M. Brooks et al.

Chronic hormone replacement therapy alters thermoregulatory and vasomotor function in postmenopausal women

J Appl Physiol

(1997)

A.M. Buchan et al.

Hypothermia but not the N-methyl-d-aspartate antagonist, MK-801, attenuates neuronal damage in gerbils subjected to transient global ischemia

J Neurosci

(1990)

C. Coimbra et al.

Diminished neuronal damage in the rat brain by late treatment with the antipyretic drug dipyrone or cooling following cerebral ischemia

Acta Neuropathol

(1996)

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17β-estradiol pretreatment reduces ca1sector cell death and the spontaneous hyperthermia that follows forebrain ischemia in the gerbil

Abstract

Section snippets

Animals

Experiment 1

Conclusions

Acknowledgments

Brain Res

Brain Res

Methods

Fertil Steril

J Neurol Sci

Brain Res

Trends Endocrinol Metab

Brain Res

Lancet

Neuroscience

Steroids

Neurosci Res

Maturitas

Brain Res

Hyperthermia delayed by 24 hours aggravates neuronal damage in rat hippocampus following global ischemia

Neurology

Chronic hormone replacement therapy alters thermoregulatory and vasomotor function in postmenopausal women

J Appl Physiol

Hypothermia but not the N-methyl-d-aspartate antagonist, MK-801, attenuates neuronal damage in gerbils subjected to transient global ischemia

J Neurosci

Diminished neuronal damage in the rat brain by late treatment with the antipyretic drug dipyrone or cooling following cerebral ischemia

Acta Neuropathol