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SCM-198 Ameliorates Cognitive Deficits, Promotes Neuronal Survival and Enhances CREB/BDNF/TrkB Signaling without Affecting Aβ Burden in AβPP/PS1 Mice.

Hong ZY, Yu SS, Wang ZJ, Zhu YZ - Int J Mol Sci (2015)

Bottom Line: SCM-198 is an alkaloid found only in Herba leonuri and it has been reported to possess considerable neuroprotective effects in animal models of ischemic stroke, Parkinson's disease and Alzheimer's disease (AD).In addition, decreases in cAMP-response element-binding protein (CREB) phosphorylation, brain-derived neurotrophic factor (BDNF) and tropomyosin-related kinase B (TrkB) phosphorylation were attenuated by SCM-198 both in vivo and in primary cortical neurons, which could be blocked by protein kinase A (PKA) inhibitors, suggesting the involvement of upstream PKA in enhancing the BDNF/TrkB/CREB signaling by SCM-198.Our results indicate that SCM-198, a drug that could promote neuronal survival and enhance BDNF/TrkB/CREB signaling, has beneficial effects on behavioral and biochemical alterations without affecting Aβ burden in AβPP/PS1 mice and might become a potential drug candidate for AD treatment in the future.

View Article: PubMed Central - PubMed

Affiliation: Shanghai Key Laboratory of Bioactive Small Molecules, Department of Pharmacology, School of Pharmacy, Fudan University, Shanghai 201203, China. cerulian@163.com.

ABSTRACT
SCM-198 is an alkaloid found only in Herba leonuri and it has been reported to possess considerable neuroprotective effects in animal models of ischemic stroke, Parkinson's disease and Alzheimer's disease (AD). In this study, we demonstrated for the first time that 3-month oral SCM-198 treatment could significantly improve both recognition and spatial memory, inhibit microgliosis and promote neuronal survival in amyloid-β protein precursor and presenilin-1(AβPP/PS1) double-transgenic mice without affecting amyloid-β (Aβ) burden. In addition, decreases in cAMP-response element-binding protein (CREB) phosphorylation, brain-derived neurotrophic factor (BDNF) and tropomyosin-related kinase B (TrkB) phosphorylation were attenuated by SCM-198 both in vivo and in primary cortical neurons, which could be blocked by protein kinase A (PKA) inhibitors, suggesting the involvement of upstream PKA in enhancing the BDNF/TrkB/CREB signaling by SCM-198. Our results indicate that SCM-198, a drug that could promote neuronal survival and enhance BDNF/TrkB/CREB signaling, has beneficial effects on behavioral and biochemical alterations without affecting Aβ burden in AβPP/PS1 mice and might become a potential drug candidate for AD treatment in the future.

No MeSH data available.


Related in: MedlinePlus

SCM-198 enhanced CREB/BDNF/TrkB signalling both in vivo and in vitro. Wild-type and AβPP/PS1 mice began receiving different treatments at 6 months of age and were fed continuously for 3 months. Proteins from hippocampus of AβPP/PS1 mice were analyzed by Western blot using antibodies against (A) p-CREB and total CREB (n = 6 mice/group); (B) BDNF and GAPDH (n = 6 mice/group) and (C) p-TrkB and total TrkB (n = 5mice/group) (SCM: SCM-198). Data represent mean ± SEM. * p < 0.05, ** p < 0.01, *** p < 0.001, Tukey’s test vs. AβPP/PS1 group; # p < 0.05, ## p < 0.01, ### p < 0.001, Tukey’s test vs. wild-type group. Primary cortical neurons were pretreated with or without 10 μM SCM-198 or 50 μM H89 (inhibitor of protein kinase A) for 1 h, followed by stimulation with 10 μM Aβ42 for 1 h; (D) After 10-min stimulation with 100 μM glutamate (Glu), proteins were extracted and analyzed by Western blot using antibodies against p-CREB and total CREB. Data represent mean ± SEM of more than four independent experiments. *** p < 0.001, Tukey’s test vs. only Glu-treated group; ## p < 0.01, Tukey’s test vs. control group; && p < 0.01. Tukey’s test vs. Glu + Aβ42-treated-group; $$ p < 0.01, Tukey’s test vs. Glu + Aβ42 + SCM-treated-group; SCM-198 at 10 μM time-dependently increased p-CREB (E,F), BDNF (E,G) and p-TrkB (E,H) expressions in primary neurons. Neurons were then pretreated with or without 10 μM SCM-198 or 50 μM H89 (inhibitor of protein kinase A) for 2 h, followed by 24-h exposure to 10 μM Aβ42. SCM-198 significantly inhibited the reductions in p-CREB (I,J), BDNF (I,K) and p-TrkB (I,L) expressions induced by Aβ42 exposure, which could be blocked by H89 treatment. Data represent mean ± SEM of more than four independent experiments. ***p < 0.001, Tukey’s test vs. only Aβ42-treated group; # p < 0.05, ## p < 0.01, ### p < 0.001, Tukey’s test vs. control group; & p < 0.05, && p < 0.01, Tukey’s test vs. SCM + Aβ42-treated-group.
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ijms-16-18544-f006: SCM-198 enhanced CREB/BDNF/TrkB signalling both in vivo and in vitro. Wild-type and AβPP/PS1 mice began receiving different treatments at 6 months of age and were fed continuously for 3 months. Proteins from hippocampus of AβPP/PS1 mice were analyzed by Western blot using antibodies against (A) p-CREB and total CREB (n = 6 mice/group); (B) BDNF and GAPDH (n = 6 mice/group) and (C) p-TrkB and total TrkB (n = 5mice/group) (SCM: SCM-198). Data represent mean ± SEM. * p < 0.05, ** p < 0.01, *** p < 0.001, Tukey’s test vs. AβPP/PS1 group; # p < 0.05, ## p < 0.01, ### p < 0.001, Tukey’s test vs. wild-type group. Primary cortical neurons were pretreated with or without 10 μM SCM-198 or 50 μM H89 (inhibitor of protein kinase A) for 1 h, followed by stimulation with 10 μM Aβ42 for 1 h; (D) After 10-min stimulation with 100 μM glutamate (Glu), proteins were extracted and analyzed by Western blot using antibodies against p-CREB and total CREB. Data represent mean ± SEM of more than four independent experiments. *** p < 0.001, Tukey’s test vs. only Glu-treated group; ## p < 0.01, Tukey’s test vs. control group; && p < 0.01. Tukey’s test vs. Glu + Aβ42-treated-group; $$ p < 0.01, Tukey’s test vs. Glu + Aβ42 + SCM-treated-group; SCM-198 at 10 μM time-dependently increased p-CREB (E,F), BDNF (E,G) and p-TrkB (E,H) expressions in primary neurons. Neurons were then pretreated with or without 10 μM SCM-198 or 50 μM H89 (inhibitor of protein kinase A) for 2 h, followed by 24-h exposure to 10 μM Aβ42. SCM-198 significantly inhibited the reductions in p-CREB (I,J), BDNF (I,K) and p-TrkB (I,L) expressions induced by Aβ42 exposure, which could be blocked by H89 treatment. Data represent mean ± SEM of more than four independent experiments. ***p < 0.001, Tukey’s test vs. only Aβ42-treated group; # p < 0.05, ## p < 0.01, ### p < 0.001, Tukey’s test vs. control group; & p < 0.05, && p < 0.01, Tukey’s test vs. SCM + Aβ42-treated-group.

Mentions: Memory decline is one of the important features of AD. Multiple lines of evidence have shown that deficits in long-term potentiation and synaptic transmission occur very early and precede massive Aβ deposition and behavioral abnormalities. The CREB protein, the phosphorylation of which is significantly decreased in both AD transgenic animal models and human AD post-mortem brains, plays a key role in memory formation [10,19,20,21]. Western blot analysis of CREB phosphorylation (p-CREB) showed a reduction by approximately 60% in the hippocampus of vehicle-treated AβPP/PS1 mice as compared with that of wild-type mice, while this reduction was dose-dependently increased by long-term SCM-198 treatment and was reversed back to wild-type levels in 100 mg/kg SCM-198-treated AβPP/PS1 group (F (3, 20) = 14.45, p < 0.0001, Figure 6A). Significant declines in BDNF and TrkB phosphorylation (p-TrkB) were also observed in vehicle-treated AβPP/PS1 group and 100 mg/kg SCM-198 significantly enhanced the BDNF (F (3, 20) = 6.228, p = 0.0037, Figure 6B) and p-TrkB levels (F (3, 16) = 7.919, p = 0.0018, Figure 6C) in AβPP/PS1 mice. No significant changes were detected in total CREB or TrkB levels. Glutamate was first used to quickly induce the elevation of p-CREB levels in vitro. In primary cortical neurons, p-CREB was strongly induced by 10-min incubation with 100 μM glutamate, while 1-h treatment of 10 μM Aβ42 decreased p-CREB levels. 1-h pretreatment of 10 μM SCM-198 significantly alleviated Aβ42-induced down-regulation of p-CREB, which could be completely blocked by 50 μM H89 (F (4, 30) = 15.87, p < 0.0001, Figure 7D). No significant changes were observed in total CREB levels. 10 μM SCM-198 itself could also time-dependently increased p-CREB (F (4, 25) = 14.03, p < 0.0001, Figure 6E,F), BDNF (F (4, 15) = 11.79, p = 0.0002, Figure 6E,G) and p-TrkB (F (4, 20) = 9.076, p= 0.0002, Figure 6E,H) levels in primary cortical neurons and significant increases were observed after 2 h treatment with SCM-198. Compared with control group, 24 h stimulation with 10 μM Aβ42 caused significant reductions in p-CREB, BDNF and p-TrkB levels, which were reversed by 2-h pretreatment with 10 μM SCM-198 in neurons and this protective effect could also be blocked by 50 μM H89 or 50 μM Rp-cAMPS. In conclusion, these results suggested that SCM-198 could enhance CREB/BDNF/TrkB signaling in AβPP/PS1 mice and prevent Aβ42-induced reductions in p-CREB (F (4, 20) = 28.23, p < 0.0001, Figure 6I,J; F (4, 20) = 87.46, p < 0.0001, Figure 7A,B), BDNF (F (4, 25) = 25.55, p < 0.0001, Figure 6I,K; F (4, 20) = 30.86, p < 0.0001, Figure 7A,C) and p-TrkB (F (4, 20) = 41.74, p < 0.0001, Figure 6I,L; F (4, 20) = 28.72, p < 0.0001, Figure 7A,D) levels in cortical neurons. Besides, the compound itself could increase p-CREB, BDNF and p-TrkB expressions, indicating that SCM-198 could promote neurotrophic signaling, at least partially, via regulating the PKA-CREB pathway.


SCM-198 Ameliorates Cognitive Deficits, Promotes Neuronal Survival and Enhances CREB/BDNF/TrkB Signaling without Affecting Aβ Burden in AβPP/PS1 Mice.

Hong ZY, Yu SS, Wang ZJ, Zhu YZ - Int J Mol Sci (2015)

SCM-198 enhanced CREB/BDNF/TrkB signalling both in vivo and in vitro. Wild-type and AβPP/PS1 mice began receiving different treatments at 6 months of age and were fed continuously for 3 months. Proteins from hippocampus of AβPP/PS1 mice were analyzed by Western blot using antibodies against (A) p-CREB and total CREB (n = 6 mice/group); (B) BDNF and GAPDH (n = 6 mice/group) and (C) p-TrkB and total TrkB (n = 5mice/group) (SCM: SCM-198). Data represent mean ± SEM. * p < 0.05, ** p < 0.01, *** p < 0.001, Tukey’s test vs. AβPP/PS1 group; # p < 0.05, ## p < 0.01, ### p < 0.001, Tukey’s test vs. wild-type group. Primary cortical neurons were pretreated with or without 10 μM SCM-198 or 50 μM H89 (inhibitor of protein kinase A) for 1 h, followed by stimulation with 10 μM Aβ42 for 1 h; (D) After 10-min stimulation with 100 μM glutamate (Glu), proteins were extracted and analyzed by Western blot using antibodies against p-CREB and total CREB. Data represent mean ± SEM of more than four independent experiments. *** p < 0.001, Tukey’s test vs. only Glu-treated group; ## p < 0.01, Tukey’s test vs. control group; && p < 0.01. Tukey’s test vs. Glu + Aβ42-treated-group; $$ p < 0.01, Tukey’s test vs. Glu + Aβ42 + SCM-treated-group; SCM-198 at 10 μM time-dependently increased p-CREB (E,F), BDNF (E,G) and p-TrkB (E,H) expressions in primary neurons. Neurons were then pretreated with or without 10 μM SCM-198 or 50 μM H89 (inhibitor of protein kinase A) for 2 h, followed by 24-h exposure to 10 μM Aβ42. SCM-198 significantly inhibited the reductions in p-CREB (I,J), BDNF (I,K) and p-TrkB (I,L) expressions induced by Aβ42 exposure, which could be blocked by H89 treatment. Data represent mean ± SEM of more than four independent experiments. ***p < 0.001, Tukey’s test vs. only Aβ42-treated group; # p < 0.05, ## p < 0.01, ### p < 0.001, Tukey’s test vs. control group; & p < 0.05, && p < 0.01, Tukey’s test vs. SCM + Aβ42-treated-group.
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ijms-16-18544-f006: SCM-198 enhanced CREB/BDNF/TrkB signalling both in vivo and in vitro. Wild-type and AβPP/PS1 mice began receiving different treatments at 6 months of age and were fed continuously for 3 months. Proteins from hippocampus of AβPP/PS1 mice were analyzed by Western blot using antibodies against (A) p-CREB and total CREB (n = 6 mice/group); (B) BDNF and GAPDH (n = 6 mice/group) and (C) p-TrkB and total TrkB (n = 5mice/group) (SCM: SCM-198). Data represent mean ± SEM. * p < 0.05, ** p < 0.01, *** p < 0.001, Tukey’s test vs. AβPP/PS1 group; # p < 0.05, ## p < 0.01, ### p < 0.001, Tukey’s test vs. wild-type group. Primary cortical neurons were pretreated with or without 10 μM SCM-198 or 50 μM H89 (inhibitor of protein kinase A) for 1 h, followed by stimulation with 10 μM Aβ42 for 1 h; (D) After 10-min stimulation with 100 μM glutamate (Glu), proteins were extracted and analyzed by Western blot using antibodies against p-CREB and total CREB. Data represent mean ± SEM of more than four independent experiments. *** p < 0.001, Tukey’s test vs. only Glu-treated group; ## p < 0.01, Tukey’s test vs. control group; && p < 0.01. Tukey’s test vs. Glu + Aβ42-treated-group; $$ p < 0.01, Tukey’s test vs. Glu + Aβ42 + SCM-treated-group; SCM-198 at 10 μM time-dependently increased p-CREB (E,F), BDNF (E,G) and p-TrkB (E,H) expressions in primary neurons. Neurons were then pretreated with or without 10 μM SCM-198 or 50 μM H89 (inhibitor of protein kinase A) for 2 h, followed by 24-h exposure to 10 μM Aβ42. SCM-198 significantly inhibited the reductions in p-CREB (I,J), BDNF (I,K) and p-TrkB (I,L) expressions induced by Aβ42 exposure, which could be blocked by H89 treatment. Data represent mean ± SEM of more than four independent experiments. ***p < 0.001, Tukey’s test vs. only Aβ42-treated group; # p < 0.05, ## p < 0.01, ### p < 0.001, Tukey’s test vs. control group; & p < 0.05, && p < 0.01, Tukey’s test vs. SCM + Aβ42-treated-group.
Mentions: Memory decline is one of the important features of AD. Multiple lines of evidence have shown that deficits in long-term potentiation and synaptic transmission occur very early and precede massive Aβ deposition and behavioral abnormalities. The CREB protein, the phosphorylation of which is significantly decreased in both AD transgenic animal models and human AD post-mortem brains, plays a key role in memory formation [10,19,20,21]. Western blot analysis of CREB phosphorylation (p-CREB) showed a reduction by approximately 60% in the hippocampus of vehicle-treated AβPP/PS1 mice as compared with that of wild-type mice, while this reduction was dose-dependently increased by long-term SCM-198 treatment and was reversed back to wild-type levels in 100 mg/kg SCM-198-treated AβPP/PS1 group (F (3, 20) = 14.45, p < 0.0001, Figure 6A). Significant declines in BDNF and TrkB phosphorylation (p-TrkB) were also observed in vehicle-treated AβPP/PS1 group and 100 mg/kg SCM-198 significantly enhanced the BDNF (F (3, 20) = 6.228, p = 0.0037, Figure 6B) and p-TrkB levels (F (3, 16) = 7.919, p = 0.0018, Figure 6C) in AβPP/PS1 mice. No significant changes were detected in total CREB or TrkB levels. Glutamate was first used to quickly induce the elevation of p-CREB levels in vitro. In primary cortical neurons, p-CREB was strongly induced by 10-min incubation with 100 μM glutamate, while 1-h treatment of 10 μM Aβ42 decreased p-CREB levels. 1-h pretreatment of 10 μM SCM-198 significantly alleviated Aβ42-induced down-regulation of p-CREB, which could be completely blocked by 50 μM H89 (F (4, 30) = 15.87, p < 0.0001, Figure 7D). No significant changes were observed in total CREB levels. 10 μM SCM-198 itself could also time-dependently increased p-CREB (F (4, 25) = 14.03, p < 0.0001, Figure 6E,F), BDNF (F (4, 15) = 11.79, p = 0.0002, Figure 6E,G) and p-TrkB (F (4, 20) = 9.076, p= 0.0002, Figure 6E,H) levels in primary cortical neurons and significant increases were observed after 2 h treatment with SCM-198. Compared with control group, 24 h stimulation with 10 μM Aβ42 caused significant reductions in p-CREB, BDNF and p-TrkB levels, which were reversed by 2-h pretreatment with 10 μM SCM-198 in neurons and this protective effect could also be blocked by 50 μM H89 or 50 μM Rp-cAMPS. In conclusion, these results suggested that SCM-198 could enhance CREB/BDNF/TrkB signaling in AβPP/PS1 mice and prevent Aβ42-induced reductions in p-CREB (F (4, 20) = 28.23, p < 0.0001, Figure 6I,J; F (4, 20) = 87.46, p < 0.0001, Figure 7A,B), BDNF (F (4, 25) = 25.55, p < 0.0001, Figure 6I,K; F (4, 20) = 30.86, p < 0.0001, Figure 7A,C) and p-TrkB (F (4, 20) = 41.74, p < 0.0001, Figure 6I,L; F (4, 20) = 28.72, p < 0.0001, Figure 7A,D) levels in cortical neurons. Besides, the compound itself could increase p-CREB, BDNF and p-TrkB expressions, indicating that SCM-198 could promote neurotrophic signaling, at least partially, via regulating the PKA-CREB pathway.

Bottom Line: SCM-198 is an alkaloid found only in Herba leonuri and it has been reported to possess considerable neuroprotective effects in animal models of ischemic stroke, Parkinson's disease and Alzheimer's disease (AD).In addition, decreases in cAMP-response element-binding protein (CREB) phosphorylation, brain-derived neurotrophic factor (BDNF) and tropomyosin-related kinase B (TrkB) phosphorylation were attenuated by SCM-198 both in vivo and in primary cortical neurons, which could be blocked by protein kinase A (PKA) inhibitors, suggesting the involvement of upstream PKA in enhancing the BDNF/TrkB/CREB signaling by SCM-198.Our results indicate that SCM-198, a drug that could promote neuronal survival and enhance BDNF/TrkB/CREB signaling, has beneficial effects on behavioral and biochemical alterations without affecting Aβ burden in AβPP/PS1 mice and might become a potential drug candidate for AD treatment in the future.

View Article: PubMed Central - PubMed

Affiliation: Shanghai Key Laboratory of Bioactive Small Molecules, Department of Pharmacology, School of Pharmacy, Fudan University, Shanghai 201203, China. cerulian@163.com.

ABSTRACT
SCM-198 is an alkaloid found only in Herba leonuri and it has been reported to possess considerable neuroprotective effects in animal models of ischemic stroke, Parkinson's disease and Alzheimer's disease (AD). In this study, we demonstrated for the first time that 3-month oral SCM-198 treatment could significantly improve both recognition and spatial memory, inhibit microgliosis and promote neuronal survival in amyloid-β protein precursor and presenilin-1(AβPP/PS1) double-transgenic mice without affecting amyloid-β (Aβ) burden. In addition, decreases in cAMP-response element-binding protein (CREB) phosphorylation, brain-derived neurotrophic factor (BDNF) and tropomyosin-related kinase B (TrkB) phosphorylation were attenuated by SCM-198 both in vivo and in primary cortical neurons, which could be blocked by protein kinase A (PKA) inhibitors, suggesting the involvement of upstream PKA in enhancing the BDNF/TrkB/CREB signaling by SCM-198. Our results indicate that SCM-198, a drug that could promote neuronal survival and enhance BDNF/TrkB/CREB signaling, has beneficial effects on behavioral and biochemical alterations without affecting Aβ burden in AβPP/PS1 mice and might become a potential drug candidate for AD treatment in the future.

No MeSH data available.


Related in: MedlinePlus