**6. Conclusion**

For the last several decades, fatty acid nutrition, in terms of quality, has been dramatically changed [92]. Consumption of saturated fatty acids, ω-6 PUFAs, and *trans* fatty acid intake has been increased [93]. Optimal dietary ω-6:ω-3 ratio should be around 1–4:1; however, this ratio has now increased to 10: 1 to 20: 1 in the Western diet [92]. Concurrently, the incidence of diseases involving inflammatory diseases, cardiovascular disease, obesity, rheumatoid arthritis, cancer, neurodegenerative, and psychiatric illnesses, such as AD and depression, are increasing with an ever-increasing rate [94]. The results of our investigations and those of the others, finally, suggest that DHA is accumulated in the synaptic plasma membranes, represses oxidative stress by increasing the antioxidative defense, decreases cholesterol in the detergent-insoluble membrane fraction (DIMF) of the brain tissues, increases synaptic plasma membrane fluidity, inhibits amyloid fibrillation and decreases amyloid toxicity and burden in the brain tissues, improves the neuronal morphology, increases memory-related protein substrates, and hence ameliorates the memory-related brain cognition (**Figure 9**). In conclusion, a balanced intake of ω-3 and ω-6 PUFAs is a must, as well as an increased intake of DHA, which might act as a signaling molecule to protect the brains from preterm-, postnatal-, and other age-related neurological diseases, such as Alzheimer's disease.

**23**

**Figure 9.**

**Author details**

Medicine, Japan

Savar, Dhaka, Bangladesh

Michio Hashimoto1

provided the original work is properly cited.

*Fatty Acids: From Membrane Ingredients to Signaling Molecules*

*DOI: http://dx.doi.org/10.5772/intechopen.80430*

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

\* and Shahdat Hossain<sup>2</sup>

\*Address all correspondence to: michio1@med.shimane-u.ac.jp

1 Department of Environmental Physiology, Shimane University Faculty of

2 Department of Biochemistry and Molecular Biology, Jahangirnagar University,

*Outlines of the effect of DHA on learning-related memory of rats. SPM = synaptic plasma membrane. DIMF = detergent-insoluble membrane fraction. All other abbreviations are same as for other figures.*

*Fatty Acids: From Membrane Ingredients to Signaling Molecules DOI: http://dx.doi.org/10.5772/intechopen.80430*

#### **Figure 9.**

*Biochemistry and Health Benefits of Fatty Acids*

*primarily in the dentate gyrus (DG) region.*

tion of learning-related brain cognition.

**6. Conclusion**

**Figure 8.**

*in vivo* neurogenesis [88] (**Figure 8B, C**), which is conducive to inhibition of the impairments of memory in aging and/or AD model rats. DHA stimulated the differentiation of neural stem cells into mature neurons by triggering the activating-type bHLH transcription factors, including neurogenin, Mash1, and NeuroD and inhibiting the repressor-type transcription factor Mes1 [89]. We also reported that DHA-derived docosanoids, such as neuroprotectin D1, help increase the memory of rats [90]. Consistent with our results, Bazan et al. [91] also reported that endogenous signaling by DHA-derived mediators sustains neuronal function and protects synapses and circuits, thus demonstrating that DHA and/or its docosanoid products might act as signaling molecules during memory processing. Finally, DHA is essential for the growth and development of brain and might play crucial roles in the forma-

*Effect of incubation of DHA on in vitro amyloid beta (Aβ) peptide fibrillation (A) and in vitro neurogenesis in NSCs culture (B) and, effect of oral administration of in vivo neurogenesis (C). Neurogenesis occurred* 

For the last several decades, fatty acid nutrition, in terms of quality, has been dramatically changed [92]. Consumption of saturated fatty acids, ω-6 PUFAs, and *trans* fatty acid intake has been increased [93]. Optimal dietary ω-6:ω-3 ratio should be around 1–4:1; however, this ratio has now increased to 10: 1 to 20: 1 in the Western diet [92]. Concurrently, the incidence of diseases involving inflammatory diseases, cardiovascular disease, obesity, rheumatoid arthritis, cancer, neurodegenerative, and psychiatric illnesses, such as AD and depression, are increasing with an ever-increasing rate [94]. The results of our investigations and those of the others, finally, suggest that DHA is accumulated in the synaptic plasma membranes, represses oxidative stress by increasing the antioxidative defense, decreases cholesterol in the detergent-insoluble membrane fraction (DIMF) of the brain tissues, increases synaptic plasma membrane fluidity, inhibits amyloid fibrillation and decreases amyloid toxicity and burden in the brain tissues, improves the neuronal morphology, increases memory-related protein substrates, and hence ameliorates the memory-related brain cognition (**Figure 9**). In conclusion, a balanced intake of ω-3 and ω-6 PUFAs is a must, as well as an increased intake of DHA, which might act as a signaling molecule to protect the brains from preterm-, postnatal-, and other age-related neurological diseases,

**22**

such as Alzheimer's disease.

*Outlines of the effect of DHA on learning-related memory of rats. SPM = synaptic plasma membrane. DIMF = detergent-insoluble membrane fraction. All other abbreviations are same as for other figures.*
