Effects of temperature alterations on population and cellular activities in hippocampal slices from mature and immature rabbit

doi:10.1016/0006-8993(88)90619-1

Brain Research

Volume 475, Issue 2, 20 December 1988, Pages 305-316

https://doi.org/10.1016/0006-8993(88)90619-1 Get rights and content

Abstract

Effects of temperature on population spike and cellular activities have been assessed in the CA1 region of hippocampal slices from mature and immature rabbit. In field potential recordings, population spike amplitude was maximal at near 30 °C for both mature and immature tissue, and fell off as temperature was either raised (to a maximum of 44 °C) or lowered (to a minimum of 20 °C). With cooling below 30 °C, population spikes decreased in amplitude and became broader; stimuli always elicited some response, and changes due to cooling were reversible. With increases in temperature, however, irreversible decrease and/or loss of population spikes occurred when tissue was warmed beyond 43 °C. Input-output curves established for mature and immature slices indicated that, at all temperatures, population spike amplitude grew more rapidly with small increases in stimulus intensity in immature slices as compared to mature slices. Intracellular recordings were made from CA1 pyramidal cells in mature and immature hippocampal slices. For both mature and immature tissues, moderate warming (to 40 °C) produced membrane hyperpolarizations in many cells, especially in the mature hippocampus. Increasing temperature beyond 40 °C led to marked depolarizations in a number of cells, a depolarization that was irreversible, particularly in mature neurons. Cooling generally produced a depolarizing shift in membrane potential and an accompanying increase in input resistance; these effects, however, were reversible. Temperature changes in both warming and cooling directions had effects on repetitive firing patterns in both mature and immature neurons. In particular, spike trains elicited by a constant current pulse at a given membrane potential became shorter. The effects of cooling on this cell parameter were reversible, but warming-induced changes were usually permanent. Irreversibility of the warming effects was more pronounced in cells from mature than from immature hippocampus. As reported previously, cooling produced marked spike broadening and changes in synaptic potentials in both mature and immature neurons. These studies confirm previously reported temperature sensitivities of neuronal properties in hippocampal slices. On the basis of these data, and reports from other laboratories, it is clear that relatively small changes in temperature can have rather dramatic effects on properties of single cells and cell populations. Such temperature sensitivity is critical in evaluating data obtained from in vitro slice preparations. These data are also helpful in trying to evaluate the effects of hyperthermia (fever) on neural function.

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^*: Present address: Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, U.S.A.

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Effects of temperature alterations on population and cellular activities in hippocampal slices from mature and immature rabbit

Abstract

Brain Research

Brain Research

Brain Research

J. Neurosci. Meth.

Comp. Biochem. Physiol.

Brain Research

Brain Research

Brain Research

Brain Research

Brain slice methods

Unit analysis of hippocampal population spikes

Exp. Brain Res.

Effect of cooling on synaptic transmission through the cuneate nucleus

Acta Physiol. Scand.

Temporal lobe volumetric cell densities in temporal lobe epilepsy

Epilepsia

Evidence of injury by heat in mammalian tissues

Am. J. Physiol.

A contribution of an electrogenic Na+ pump to membrane potential inAplysia neurons

J. Gen. Physiol.

A contribution of an electrogenic Na⁺ pump to membrane potential inAplysia neurons