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Increased orexin expression promotes sleep/wake disturbances in the SOD1-G93A mouse model of amyotrophic lateral sclerosis.

Liu R, Sheng ZF, Cai B, Zhang YH, Fan DS - Chin. Med. J. (2015)

Bottom Line: Correlation analysis confirmed moderate to high correlations between sleep/wake time (total sleep time, wakefulness time, rapid eye movement [REM] sleep time, non-REM sleep time, and deep sleep time) and increase in orexins (prepro-orexin, orexin A and B).Increased orexins may promote wakefulness and result in these disturbances before and after disease onset, thus making them potential therapeutic targets for amelioration of sleep disturbances in ALS.Further studies are required to elucidate the underlying mechanisms in the future.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Peking University Third Hospital, Beijing 100191, China.

ABSTRACT

Background: Sleep/wake disturbances in patients with amyotrophic lateral sclerosis (ALS) are well-documented, however, no animal or mechanistic studies on these disturbances exist. Orexin is a crucial neurotransmitter in promoting wakefulness in sleep/wake regulation, and may play an important role in sleep disturbances in ALS. In this study, we used SOD1-G93A transgenic mice as an ALS mouse model to investigate the sleep/wake disturbances and their possible mechanisms in ALS.

Methods: Electroencephalogram/electromyogram recordings were performed in SOD1-G93A transgenic mice and their littermate control mice at the ages of 90 and 120 days, and the samples obtained from these groups were subjected to quantitative reverse transcriptase-polymerase chain reaction, western blotting, and enzyme-linked immunosorbent assay.

Results: For the first time in SOD1-G93A transgenic mice, we observed significantly increased wakefulness, reduced sleep time, and up-regulated orexins (prepro-orexin, orexin A and B) at both 90 and 120 days. Correlation analysis confirmed moderate to high correlations between sleep/wake time (total sleep time, wakefulness time, rapid eye movement [REM] sleep time, non-REM sleep time, and deep sleep time) and increase in orexins (prepro-orexin, orexin A and B).

Conclusion: Sleep/wake disturbances occur before disease onset in this ALS mouse model. Increased orexins may promote wakefulness and result in these disturbances before and after disease onset, thus making them potential therapeutic targets for amelioration of sleep disturbances in ALS. Further studies are required to elucidate the underlying mechanisms in the future.

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Orexin A and B increase in SOD1-G93A transgenic mice. (a-c) ELISA reveals that orexin A levels are enhanced in the hypothalamus and brain stem of the 90 and 120 days SOD1-G93A transgenic mice than controls, but there is no significant difference for orexin A in the CSF. (d-f) ELISA shows increased the level of orexin B in the hypothalamus and brain stem of the 90 and 120 days SOD1-G93A transgenic mice compared with control, but no significant difference is seen in the CSF. Data are expressed as mean ± standard error (n = 4–6/group). *P < 0.05 and †P < 0.01. HT: Hypothalamus; BS: Brain stem; CSF: Cerebrospinal fluid; ELISA: Enzyme-linked immunosorbent assay.
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Figure 3: Orexin A and B increase in SOD1-G93A transgenic mice. (a-c) ELISA reveals that orexin A levels are enhanced in the hypothalamus and brain stem of the 90 and 120 days SOD1-G93A transgenic mice than controls, but there is no significant difference for orexin A in the CSF. (d-f) ELISA shows increased the level of orexin B in the hypothalamus and brain stem of the 90 and 120 days SOD1-G93A transgenic mice compared with control, but no significant difference is seen in the CSF. Data are expressed as mean ± standard error (n = 4–6/group). *P < 0.05 and †P < 0.01. HT: Hypothalamus; BS: Brain stem; CSF: Cerebrospinal fluid; ELISA: Enzyme-linked immunosorbent assay.

Mentions: We then tested the protein levels of orexin A and B, using ELISA. In the hypothalamus, the level of orexin A was significantly enhanced in the 90-day ([2126.47 ± 70.65 pg/mg] vs. [1591.52 ± 61.25 pg/mg] protein, P < 0.01) and 120-day ([2166.32 ± 115.98 pg/mg] vs. [1446.18 ± 41.31 pg/mg] protein, P < 0.01) SOD1-G93A transgenic mice, compared to their respective littermate control mice [Figure 3a]. The level of orexin A was also elevated significantly in the brain stem of the 90-day ([1540.93 ± 34.87 pg/mg] vs. [1170.04 ± 47.73 pg/mg] protein, P < 0.01) and 120-day ([1583.96 ± 21.64 pg/mg] vs. [1224.87 ± 51.62 pg/mg] protein, P < 0.01) transgenic groups [Figure 3b]. There was no significant difference in orexin A levels between the SOD1-G93A transgenic mice and control groups in the CSF, at either time points [Figure 3c]. Similarly, orexin B levels were also significantly increased in the hypothalamus of the 90-day ([3485.35 ± 74.62 pg/mg] vs. [2352.45 ± 142.56 pg/mg] protein, P < 0.01) and 120-day ([3656.34 ± 139.17 pg/mg] vs. [2411.57 ± 117.70 pg/mg] protein, P < 0.01) SOD1-G93A transgenic mice [Figure 3d]. In the brain stem, orexin B was also significantly enhanced in both transgenic groups (90-day: [2726.79 ± 34.06 pg/mg] vs. [2411.70 ± 64.18 pg/mg] protein, P < 0.01 and 120-day: [2736.45 ± 57.32 pg/mg] vs. [2369.33 ± 83.57 pg/mg] protein, P < 0.05) as compared to littermate controls [Figure 3e]. In the CSF, no significant difference was found in orexin B levels between the respective transgenic and control groups [Figure 3f].


Increased orexin expression promotes sleep/wake disturbances in the SOD1-G93A mouse model of amyotrophic lateral sclerosis.

Liu R, Sheng ZF, Cai B, Zhang YH, Fan DS - Chin. Med. J. (2015)

Orexin A and B increase in SOD1-G93A transgenic mice. (a-c) ELISA reveals that orexin A levels are enhanced in the hypothalamus and brain stem of the 90 and 120 days SOD1-G93A transgenic mice than controls, but there is no significant difference for orexin A in the CSF. (d-f) ELISA shows increased the level of orexin B in the hypothalamus and brain stem of the 90 and 120 days SOD1-G93A transgenic mice compared with control, but no significant difference is seen in the CSF. Data are expressed as mean ± standard error (n = 4–6/group). *P < 0.05 and †P < 0.01. HT: Hypothalamus; BS: Brain stem; CSF: Cerebrospinal fluid; ELISA: Enzyme-linked immunosorbent assay.
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Related In: Results  -  Collection

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Figure 3: Orexin A and B increase in SOD1-G93A transgenic mice. (a-c) ELISA reveals that orexin A levels are enhanced in the hypothalamus and brain stem of the 90 and 120 days SOD1-G93A transgenic mice than controls, but there is no significant difference for orexin A in the CSF. (d-f) ELISA shows increased the level of orexin B in the hypothalamus and brain stem of the 90 and 120 days SOD1-G93A transgenic mice compared with control, but no significant difference is seen in the CSF. Data are expressed as mean ± standard error (n = 4–6/group). *P < 0.05 and †P < 0.01. HT: Hypothalamus; BS: Brain stem; CSF: Cerebrospinal fluid; ELISA: Enzyme-linked immunosorbent assay.
Mentions: We then tested the protein levels of orexin A and B, using ELISA. In the hypothalamus, the level of orexin A was significantly enhanced in the 90-day ([2126.47 ± 70.65 pg/mg] vs. [1591.52 ± 61.25 pg/mg] protein, P < 0.01) and 120-day ([2166.32 ± 115.98 pg/mg] vs. [1446.18 ± 41.31 pg/mg] protein, P < 0.01) SOD1-G93A transgenic mice, compared to their respective littermate control mice [Figure 3a]. The level of orexin A was also elevated significantly in the brain stem of the 90-day ([1540.93 ± 34.87 pg/mg] vs. [1170.04 ± 47.73 pg/mg] protein, P < 0.01) and 120-day ([1583.96 ± 21.64 pg/mg] vs. [1224.87 ± 51.62 pg/mg] protein, P < 0.01) transgenic groups [Figure 3b]. There was no significant difference in orexin A levels between the SOD1-G93A transgenic mice and control groups in the CSF, at either time points [Figure 3c]. Similarly, orexin B levels were also significantly increased in the hypothalamus of the 90-day ([3485.35 ± 74.62 pg/mg] vs. [2352.45 ± 142.56 pg/mg] protein, P < 0.01) and 120-day ([3656.34 ± 139.17 pg/mg] vs. [2411.57 ± 117.70 pg/mg] protein, P < 0.01) SOD1-G93A transgenic mice [Figure 3d]. In the brain stem, orexin B was also significantly enhanced in both transgenic groups (90-day: [2726.79 ± 34.06 pg/mg] vs. [2411.70 ± 64.18 pg/mg] protein, P < 0.01 and 120-day: [2736.45 ± 57.32 pg/mg] vs. [2369.33 ± 83.57 pg/mg] protein, P < 0.05) as compared to littermate controls [Figure 3e]. In the CSF, no significant difference was found in orexin B levels between the respective transgenic and control groups [Figure 3f].

Bottom Line: Correlation analysis confirmed moderate to high correlations between sleep/wake time (total sleep time, wakefulness time, rapid eye movement [REM] sleep time, non-REM sleep time, and deep sleep time) and increase in orexins (prepro-orexin, orexin A and B).Increased orexins may promote wakefulness and result in these disturbances before and after disease onset, thus making them potential therapeutic targets for amelioration of sleep disturbances in ALS.Further studies are required to elucidate the underlying mechanisms in the future.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Peking University Third Hospital, Beijing 100191, China.

ABSTRACT

Background: Sleep/wake disturbances in patients with amyotrophic lateral sclerosis (ALS) are well-documented, however, no animal or mechanistic studies on these disturbances exist. Orexin is a crucial neurotransmitter in promoting wakefulness in sleep/wake regulation, and may play an important role in sleep disturbances in ALS. In this study, we used SOD1-G93A transgenic mice as an ALS mouse model to investigate the sleep/wake disturbances and their possible mechanisms in ALS.

Methods: Electroencephalogram/electromyogram recordings were performed in SOD1-G93A transgenic mice and their littermate control mice at the ages of 90 and 120 days, and the samples obtained from these groups were subjected to quantitative reverse transcriptase-polymerase chain reaction, western blotting, and enzyme-linked immunosorbent assay.

Results: For the first time in SOD1-G93A transgenic mice, we observed significantly increased wakefulness, reduced sleep time, and up-regulated orexins (prepro-orexin, orexin A and B) at both 90 and 120 days. Correlation analysis confirmed moderate to high correlations between sleep/wake time (total sleep time, wakefulness time, rapid eye movement [REM] sleep time, non-REM sleep time, and deep sleep time) and increase in orexins (prepro-orexin, orexin A and B).

Conclusion: Sleep/wake disturbances occur before disease onset in this ALS mouse model. Increased orexins may promote wakefulness and result in these disturbances before and after disease onset, thus making them potential therapeutic targets for amelioration of sleep disturbances in ALS. Further studies are required to elucidate the underlying mechanisms in the future.

Show MeSH
Related in: MedlinePlus