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Male-Specific Alleviation of Iron-Induced Striatal Injury by Inhibition of Autophagy.

Wang LF, Yokoyama KK, Chen TY, Hsiao HW, Chiang PC, Hsieh YC, Lo S, Hsu C - PLoS ONE (2015)

Bottom Line: Pre-treatment of FC-infused females with rapamycin increased the FC-induced behavioral deficit and DRD2 neuron death.These results suggest that autophagy in FC-infusion males is overactive with maladaptive consequences and inhibition of autophagy decreases the severity of FC-induced striatal injury in males.These findings present prospects for male-specific therapeutic strategy that targets autophagy in patients suffering from iron overload.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicinal and Applied Chemistry, College of Life Science, Kaohsiung Medical University, Kaohsiung, Taiwan.

ABSTRACT
Men exhibit a worse survival rate than premenopausal women after intracerebral hemorrhage (ICH), however, no sex-specific management has been concerned. In a rat model involving infusion of ferrous citrate (FC) that simulates iron accumulation after hemorrhage, a higher degree of autophagy associated with higher injury severity was observed in striatum of males than in females. Since the imbalance between the levels of autophagy and energy demand may lead to cell death, we proposed that FC-induced autophagy is detrimental in a male specific manner and autophagy modulation affects injury severity in a sex-dependent manner. Rapamycin, an autophagy inducer, and conditional knockout gene of autophagy-related protein 7 (Atg7) in dopamine receptor D2 (DRD2) neurons were used to test our hypothesis using a mouse model with striatal FC infusion. The result showed that the levels of autophagic cell death and injury severity were higher in male than in female mice. Pre-treatment of FC-infused females with rapamycin increased the FC-induced behavioral deficit and DRD2 neuron death. However, DRD2 neuron-specific knockout of Atg7 decreased FC-induced injury severity and the number of TUNEL(+) DRD2 neurons in males. These results suggest that autophagy in FC-infusion males is overactive with maladaptive consequences and inhibition of autophagy decreases the severity of FC-induced striatal injury in males. These findings present prospects for male-specific therapeutic strategy that targets autophagy in patients suffering from iron overload.

No MeSH data available.


Related in: MedlinePlus

Heterozygous Atg7 knockout in striatal DRD2 neurons.(A) Representative images of ATG7 immunoreactive DRD2 neurons. The pictures were captured under fluorescent microscope after immunostaining. Arrows indicate blue nuclei surrounded by immunoreactivities of ATG7 and DRD2. (B) total number of DAPI(+) nuclei. (C) percentage of DRD2 neurons in total nuclei. (D) percentage of ATG7 immunoreactive DRD2 neurons in total nuclei. The number of immunoreactive cells was counted in every fifteenth section of the striatum. Five fields in each tissue section were randomly selected for counting. Data are presented as the means ± SDs (number of mice was 4 in each group). Atg7 KO significantly decreased the percentage of ATG7(+) DRD2 neurons in the striatum of both male (white column) and female (black column) mice. **p< 0.01 compared with sex-matched Atg7F/F groups.
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pone.0131224.g005: Heterozygous Atg7 knockout in striatal DRD2 neurons.(A) Representative images of ATG7 immunoreactive DRD2 neurons. The pictures were captured under fluorescent microscope after immunostaining. Arrows indicate blue nuclei surrounded by immunoreactivities of ATG7 and DRD2. (B) total number of DAPI(+) nuclei. (C) percentage of DRD2 neurons in total nuclei. (D) percentage of ATG7 immunoreactive DRD2 neurons in total nuclei. The number of immunoreactive cells was counted in every fifteenth section of the striatum. Five fields in each tissue section were randomly selected for counting. Data are presented as the means ± SDs (number of mice was 4 in each group). Atg7 KO significantly decreased the percentage of ATG7(+) DRD2 neurons in the striatum of both male (white column) and female (black column) mice. **p< 0.01 compared with sex-matched Atg7F/F groups.

Mentions: To address the effects of neuron-specific autophagy inhibition on iron toxicity, heterozygote-conditional knockout mice in which Atg7 was deleted in the DRD2 neurons (Atg7+/-Drd2-Cre) were used. The knockdown efficiency of Atg7 in the DRD2 neurons was confirmed by counting the numbers of ATG7-immunoreactive DRD2 neurons. As shown in Fig 5A, in both the male and female groups, the numbers of ATG7-immunoreactive DRD2 neurons were decreased in the striatums of the Atg7+/-Drd2-Cre mice compared with those of the Atg7F/F mice. The representative images of striatum containing brain sections after HE stain were showed in the S5 Fig. The quantitative result showed that there were no differences in the total numbers of nuclei or the percentages of DRD2 neurons in the total nuclei between the Atg7+/-Drd2-Cre and wild-type Atg7F/F mice (Fig 5B and 5C). The percentages of ATG7-immunoreactive DRD2 neurons in the striatums of the male and female Atg7+/-Drd2-Cre mice were significantly lower than those in the male and female Atg7F/F mice by 44% and 33%, respectively (Fig 5D).


Male-Specific Alleviation of Iron-Induced Striatal Injury by Inhibition of Autophagy.

Wang LF, Yokoyama KK, Chen TY, Hsiao HW, Chiang PC, Hsieh YC, Lo S, Hsu C - PLoS ONE (2015)

Heterozygous Atg7 knockout in striatal DRD2 neurons.(A) Representative images of ATG7 immunoreactive DRD2 neurons. The pictures were captured under fluorescent microscope after immunostaining. Arrows indicate blue nuclei surrounded by immunoreactivities of ATG7 and DRD2. (B) total number of DAPI(+) nuclei. (C) percentage of DRD2 neurons in total nuclei. (D) percentage of ATG7 immunoreactive DRD2 neurons in total nuclei. The number of immunoreactive cells was counted in every fifteenth section of the striatum. Five fields in each tissue section were randomly selected for counting. Data are presented as the means ± SDs (number of mice was 4 in each group). Atg7 KO significantly decreased the percentage of ATG7(+) DRD2 neurons in the striatum of both male (white column) and female (black column) mice. **p< 0.01 compared with sex-matched Atg7F/F groups.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4492841&req=5

pone.0131224.g005: Heterozygous Atg7 knockout in striatal DRD2 neurons.(A) Representative images of ATG7 immunoreactive DRD2 neurons. The pictures were captured under fluorescent microscope after immunostaining. Arrows indicate blue nuclei surrounded by immunoreactivities of ATG7 and DRD2. (B) total number of DAPI(+) nuclei. (C) percentage of DRD2 neurons in total nuclei. (D) percentage of ATG7 immunoreactive DRD2 neurons in total nuclei. The number of immunoreactive cells was counted in every fifteenth section of the striatum. Five fields in each tissue section were randomly selected for counting. Data are presented as the means ± SDs (number of mice was 4 in each group). Atg7 KO significantly decreased the percentage of ATG7(+) DRD2 neurons in the striatum of both male (white column) and female (black column) mice. **p< 0.01 compared with sex-matched Atg7F/F groups.
Mentions: To address the effects of neuron-specific autophagy inhibition on iron toxicity, heterozygote-conditional knockout mice in which Atg7 was deleted in the DRD2 neurons (Atg7+/-Drd2-Cre) were used. The knockdown efficiency of Atg7 in the DRD2 neurons was confirmed by counting the numbers of ATG7-immunoreactive DRD2 neurons. As shown in Fig 5A, in both the male and female groups, the numbers of ATG7-immunoreactive DRD2 neurons were decreased in the striatums of the Atg7+/-Drd2-Cre mice compared with those of the Atg7F/F mice. The representative images of striatum containing brain sections after HE stain were showed in the S5 Fig. The quantitative result showed that there were no differences in the total numbers of nuclei or the percentages of DRD2 neurons in the total nuclei between the Atg7+/-Drd2-Cre and wild-type Atg7F/F mice (Fig 5B and 5C). The percentages of ATG7-immunoreactive DRD2 neurons in the striatums of the male and female Atg7+/-Drd2-Cre mice were significantly lower than those in the male and female Atg7F/F mice by 44% and 33%, respectively (Fig 5D).

Bottom Line: Pre-treatment of FC-infused females with rapamycin increased the FC-induced behavioral deficit and DRD2 neuron death.These results suggest that autophagy in FC-infusion males is overactive with maladaptive consequences and inhibition of autophagy decreases the severity of FC-induced striatal injury in males.These findings present prospects for male-specific therapeutic strategy that targets autophagy in patients suffering from iron overload.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicinal and Applied Chemistry, College of Life Science, Kaohsiung Medical University, Kaohsiung, Taiwan.

ABSTRACT
Men exhibit a worse survival rate than premenopausal women after intracerebral hemorrhage (ICH), however, no sex-specific management has been concerned. In a rat model involving infusion of ferrous citrate (FC) that simulates iron accumulation after hemorrhage, a higher degree of autophagy associated with higher injury severity was observed in striatum of males than in females. Since the imbalance between the levels of autophagy and energy demand may lead to cell death, we proposed that FC-induced autophagy is detrimental in a male specific manner and autophagy modulation affects injury severity in a sex-dependent manner. Rapamycin, an autophagy inducer, and conditional knockout gene of autophagy-related protein 7 (Atg7) in dopamine receptor D2 (DRD2) neurons were used to test our hypothesis using a mouse model with striatal FC infusion. The result showed that the levels of autophagic cell death and injury severity were higher in male than in female mice. Pre-treatment of FC-infused females with rapamycin increased the FC-induced behavioral deficit and DRD2 neuron death. However, DRD2 neuron-specific knockout of Atg7 decreased FC-induced injury severity and the number of TUNEL(+) DRD2 neurons in males. These results suggest that autophagy in FC-infusion males is overactive with maladaptive consequences and inhibition of autophagy decreases the severity of FC-induced striatal injury in males. These findings present prospects for male-specific therapeutic strategy that targets autophagy in patients suffering from iron overload.

No MeSH data available.


Related in: MedlinePlus