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Effects of cold exposure on behavioral and electrophysiological parameters related with hippocampal function in rats.

Elmarzouki H, Aboussaleh Y, Bitiktas S, Suer C, Artis AS, Dolu N, Ahami A - Front Cell Neurosci (2014)

Bottom Line: Meanwhile cold exposure did not affect the body weight (C: 221 ± 2.5 vs.S: 222 ± 1.7) but it impacts the adrenal gland relative weight (S: 27.1 ± 1.8 mg vs.C: 26.2 ± 1.4 mg).

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Nutrition and Health, Department of Biology, Faculty of Science, Ibn Tofail University Kenitra, Morocco.

ABSTRACT

Aim: Behavioral and mental changes may occur in people exposed to cold stress by decreasing their work efficiency and their mental capacity while increasing the number of accidents on the job site. The goal of this study was to explore the effect of cold stress in spatial learning performance excitability and LTP.

Materials and methods: Three to four month old rats were randomly divided into four groups to form a control group and a cold stress group for each sex. The groups of cold stressed animals were placed in a cold room ambient temperature of 4°C for 2 h day. Adrenal glands and body weight (g) were recorded in control and stressed rats during the cold exposure. Spatial learning (acquisition phase) and memory (probe trial) were tested in the Morris water maze (MWM) immediately after daily exposure. Latency to locate the hidden platform, distance moved (DM), mean distance to platform, swim speed (SS) and time spent in the platform quadrant were compared between genders and treatments. Field potential recordings were made, under urethane anesthesia, from the dentate gyrus (DG) granule-cell layer, with stimulation of the medial perforant pathway 2 h after the probe trial. This study examined spatial memory as measured by MWM performance and hippocampal long-term potentiation (LTP) in the DG after exposure to cold in a repeated stress condition for 2 h/day for 5 days.

Results: The cold-exposed female rats needed less time to find the hidden platform on day 1 (43.0 ± 13.9 s vs. 63.2 ± 13.2 s), day 2 (18.2 ± 8.4 s vs. 40.9 ± 12.2 s) and on day 4 (8.0 ± 2.1 s vs. 17.2 ± 7.0 s) while cold-exposed male rats showed a decreased escape latency (EL) on day 1 only (37.3 ± 12.5 s vs. 75.4 ± 13.1 s). Cold-exposed male rats spent less time in the target quadrant (30.08 ± 6.11%) than the control male rats (37.33 ± 8.89%). Two hour cold exposure decreased population spike (PS) potentiation during both induction (218.3 ± 21.6 vs. 304.5 ± 18.8%) and maintenance intervals (193.9 ± 24.5 vs. 276.6 ± 25.4%) in male rats. Meanwhile cold exposure did not affect the body weight (C: 221 ± 2.5 vs. S: 222 ± 1.7) but it impacts the adrenal gland relative weight (S: 27.1 ± 1.8 mg vs. C: 26.2 ± 1.4 mg).

Conclusion: Overall, the results show that repeated cold exposure can selectively improve spatial learning in adult female rats, but impaired retention memory for platform location in male rats. It is possible that impaired LTP underlies some of the impaired retention memory caused by cold exposure in the male rats.

No MeSH data available.


Related in: MedlinePlus

Absolute input–output curves of the population spike (PS) amplitude (left) and field excitatory postsynaptic potential (EPSP) slope (right) in the dentate gyrus (DG) area of the control (male, black square, n = 6; female, black circle, n = 6) and intermittent cold stress (male, empty square, n = 6; female, empty circle, n = 6) groups as a function of stimulus intensity before induction of LTP. Bars are standard errors of the means.
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Figure 3: Absolute input–output curves of the population spike (PS) amplitude (left) and field excitatory postsynaptic potential (EPSP) slope (right) in the dentate gyrus (DG) area of the control (male, black square, n = 6; female, black circle, n = 6) and intermittent cold stress (male, empty square, n = 6; female, empty circle, n = 6) groups as a function of stimulus intensity before induction of LTP. Bars are standard errors of the means.

Mentions: To determine whether behavioral changes in response to cold stress are parallel with neuronal activity, we investigated the baseline and stimulated activity of the DG. In order to verify if the exposure to intermittent cold stress influenced the basal circuitry properties of the DG, average EPSP slopes and PS amplitudes were plotted against stimulus intensities of 100–1500 μA (I/O curves, Figure 3). Repeated-measures ANOVAs with Treatment and Gender as between-subjects factors showed that neither cold exposure (Fs(7,140) = 1.638 and 1.049) nor gender (F(7,140) = 0.122 and 1.015) had a significant effect on PS amplitude across the stimulus intensity range (p > 0.05). Moreover, Interaction effect Treatment × Gender (Fs(7,140) = 1.168 and 1.113) did not reach a significant level. These results show that cold stress does not change I/O curves, indicating no overall change in the baseline transmission of the Perforant Pathway—DG synapsis.


Effects of cold exposure on behavioral and electrophysiological parameters related with hippocampal function in rats.

Elmarzouki H, Aboussaleh Y, Bitiktas S, Suer C, Artis AS, Dolu N, Ahami A - Front Cell Neurosci (2014)

Absolute input–output curves of the population spike (PS) amplitude (left) and field excitatory postsynaptic potential (EPSP) slope (right) in the dentate gyrus (DG) area of the control (male, black square, n = 6; female, black circle, n = 6) and intermittent cold stress (male, empty square, n = 6; female, empty circle, n = 6) groups as a function of stimulus intensity before induction of LTP. Bars are standard errors of the means.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4150461&req=5

Figure 3: Absolute input–output curves of the population spike (PS) amplitude (left) and field excitatory postsynaptic potential (EPSP) slope (right) in the dentate gyrus (DG) area of the control (male, black square, n = 6; female, black circle, n = 6) and intermittent cold stress (male, empty square, n = 6; female, empty circle, n = 6) groups as a function of stimulus intensity before induction of LTP. Bars are standard errors of the means.
Mentions: To determine whether behavioral changes in response to cold stress are parallel with neuronal activity, we investigated the baseline and stimulated activity of the DG. In order to verify if the exposure to intermittent cold stress influenced the basal circuitry properties of the DG, average EPSP slopes and PS amplitudes were plotted against stimulus intensities of 100–1500 μA (I/O curves, Figure 3). Repeated-measures ANOVAs with Treatment and Gender as between-subjects factors showed that neither cold exposure (Fs(7,140) = 1.638 and 1.049) nor gender (F(7,140) = 0.122 and 1.015) had a significant effect on PS amplitude across the stimulus intensity range (p > 0.05). Moreover, Interaction effect Treatment × Gender (Fs(7,140) = 1.168 and 1.113) did not reach a significant level. These results show that cold stress does not change I/O curves, indicating no overall change in the baseline transmission of the Perforant Pathway—DG synapsis.

Bottom Line: Meanwhile cold exposure did not affect the body weight (C: 221 ± 2.5 vs.S: 222 ± 1.7) but it impacts the adrenal gland relative weight (S: 27.1 ± 1.8 mg vs.C: 26.2 ± 1.4 mg).

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Nutrition and Health, Department of Biology, Faculty of Science, Ibn Tofail University Kenitra, Morocco.

ABSTRACT

Aim: Behavioral and mental changes may occur in people exposed to cold stress by decreasing their work efficiency and their mental capacity while increasing the number of accidents on the job site. The goal of this study was to explore the effect of cold stress in spatial learning performance excitability and LTP.

Materials and methods: Three to four month old rats were randomly divided into four groups to form a control group and a cold stress group for each sex. The groups of cold stressed animals were placed in a cold room ambient temperature of 4°C for 2 h day. Adrenal glands and body weight (g) were recorded in control and stressed rats during the cold exposure. Spatial learning (acquisition phase) and memory (probe trial) were tested in the Morris water maze (MWM) immediately after daily exposure. Latency to locate the hidden platform, distance moved (DM), mean distance to platform, swim speed (SS) and time spent in the platform quadrant were compared between genders and treatments. Field potential recordings were made, under urethane anesthesia, from the dentate gyrus (DG) granule-cell layer, with stimulation of the medial perforant pathway 2 h after the probe trial. This study examined spatial memory as measured by MWM performance and hippocampal long-term potentiation (LTP) in the DG after exposure to cold in a repeated stress condition for 2 h/day for 5 days.

Results: The cold-exposed female rats needed less time to find the hidden platform on day 1 (43.0 ± 13.9 s vs. 63.2 ± 13.2 s), day 2 (18.2 ± 8.4 s vs. 40.9 ± 12.2 s) and on day 4 (8.0 ± 2.1 s vs. 17.2 ± 7.0 s) while cold-exposed male rats showed a decreased escape latency (EL) on day 1 only (37.3 ± 12.5 s vs. 75.4 ± 13.1 s). Cold-exposed male rats spent less time in the target quadrant (30.08 ± 6.11%) than the control male rats (37.33 ± 8.89%). Two hour cold exposure decreased population spike (PS) potentiation during both induction (218.3 ± 21.6 vs. 304.5 ± 18.8%) and maintenance intervals (193.9 ± 24.5 vs. 276.6 ± 25.4%) in male rats. Meanwhile cold exposure did not affect the body weight (C: 221 ± 2.5 vs. S: 222 ± 1.7) but it impacts the adrenal gland relative weight (S: 27.1 ± 1.8 mg vs. C: 26.2 ± 1.4 mg).

Conclusion: Overall, the results show that repeated cold exposure can selectively improve spatial learning in adult female rats, but impaired retention memory for platform location in male rats. It is possible that impaired LTP underlies some of the impaired retention memory caused by cold exposure in the male rats.

No MeSH data available.


Related in: MedlinePlus