Anat Cell Biol.  2023 Jun;56(2):219-227. 10.5115/acb.22.220.

Safflower seed oil, a rich source of linoleic acid, stimulates hypothalamic neurogenesis in vivo

• Barmak MJ
• Nouri E
• Shahraki MH
• Ghalamfarsa G
• Zibara K
• Delaviz H
• Ghanbari A

• KMID: 2544084
• DOI: http://doi.org/10.5115/acb.22.220

Abstract

Adult neurogenesis has been reported in the hypothalamus, subventricular zone and subgranular zone in the hippocamp. Recent studies indicated that new cells in the hypothalamus are affected by diet. We previously showed beneficial effects of safflower seed oil (SSO), a rich source of linoleic acid (LA; 74%), on proliferation and differentiation of neural stem cells (NSCs) in vitro. In this study, the effect of SSO on hypothalamic neurogenesis was investigated in vivo, in comparison to synthetic LA. Adult mice were treated with SSO (400 mg/kg) and pure synthetic LA (300 mg/kg), at similar concentrations of LA, for 8 weeks and then hypothalamic NSCs were cultured and subsequently used for Neurosphere-forming assay. In addition, serum levels of brain-derived neurotrophic factor (BNDF) were measured using enzyme-linked immunosorbent assay. Administration of SSO for 8 weeks in adult mice promoted the proliferation of NSCs isolated from SSO-treated mice. Immunofluorescence staining of the hypothalamus showed that the frequency of astrocytes (glial fibrillary acidic protein⁺ cells) are not affected by LA or SSO. However, the frequency of immature (doublecortin⁺ cells) and mature (neuronal nuclei⁺ cells) neurons significantly increased in LA- and SSO-treated mice, compared to vehicle. Furthermore, both LA and SSO caused a significant increase in the serum levels of BDNF. Importantly, SSO acted more potently than LA in all experiments. The presence of other fatty acids in SSO, such as oleic acid and palmitic acid, suggests that they could be responsible for SSO positive effect on hypothalamic proliferation and neurogenesis, compared to synthetic LA at similar concentrations.

Keyword

Safflower seed oil; Linoleic acid; Neurogenesis; Hypothalamus

Figure

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  Fig. 1 The effect of SSO and LA on NSC neurosphere formation. (A) Representative images of neurospheres in the different groups. Scale bar=100 μm. (B) SSO, but not LA, significantly increased neurosphere formation. (C) Cell counts obtained from neurospheres showed an increase of the mean cell number for both SSO or LA, compared to vehicle. Data were expressed as mean±standard error of the mean and each experiment included 10 replicates per condition (n=10). Statistical analyses were performed by one-way analysis of variance followed by Tukey’s test. Significance is indicated by *P<0.05, **P<0.01, and ***P<0.001. SSO, safflower seed oil; LA, linoleic acid; NSC, neural stem cell; Ctrl, control mice; Vehicle, vehicle mice.

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  Fig. 2 Immunofluorescence staining of hypothalamic astrocytes in vivo. (A) Astrocytes were labeled by an antibody against GFAP. Scale bar=100 μm. (B) Quantitative data of astrocytes in the hypothalamus in vivo. Data are presented as mean±standard error of the mean. Statistical analyses were performed by one-way analysis of variance followed by Tukey’s test. GFAP, glial fibrillary acidic protein; Ctrl, control mice; Vehicle, vehicle mice; LA, linoleic acid; SSO, safflower seed oil.

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  Fig. 3 Immunofluorescence staining of hypothalamic mature neurons in vivo. (A) Mature neurons were labeled by an antibody against NeuN. Scale bar=100 μm. (B) Quantitative data of neurons in the hypothalamus in vivo. Data are presented as mean±standard error of the mean. Statistical analyses were performed by one-way analysis of variance followed by Tukey’s test. Significance is indicated by *P<0.05 and ****P<0.0001. NeuN, neuronal nuclei; Ctrl, control mice; Vehicle, vehicle mice; LA, linoleic acid; SSO, safflower seed oil.

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  Fig. 4 Immunofluorescence staining of hypothalamic immature neurons in vivo. (A) Immature neurons were labeled by an antibody against DCX. Scale bar=200 μm. (B) Quantitative data of immature neurons in the hypothalamus in vivo. Data are presented as mean±standard error of the mean. Statistical analyses were performed by one-way analysis of variance followed by Tukey’s test. Significance is indicated by *P<0.05, ***P<0.01, and ****P<0.0001. DCX, doublecortin; Ctrl, control mice; Vehicle, vehicle mice; LA, linoleic acid; SSO, safflower seed oil.

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  Fig. 5 Serum levels of BDNF. (A-D) A scatter plot with correlation coefficients for SSO and LA groups. Seven mice per group (n=7) were used. Statistical analyses were performed by one-way analysis of variance followed by Tukey’s test. Significance is indicated by *P<0.05, and ****P<0.0001. BDNF, brain-derived neurotrophic factor; NeuN, neuronal nuclei; DCX, doublecortin; Ctrl, control mice; Vehicle, vehicle mice; LA, linoleic acid; SSO, safflower seed oil.

Reference

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