Tamotsu studies: Taking plasmalogen with food increases the content of plasmalogen in erythrocyte membranes in rats

Intake of plasmalogen with food increases the content of plasmalogen in the membranes of erythrocytes in rats

Mawatari et al. Lipids in Health and Disease 2012,11:161
http://www.lipidworid.com/content/11/1/161
https://pubmed.ncbi.nlm.nih.gov/23170810/
Shiro Mawatari1*, Toshihiko Katafuchi 2, Kiyotaka Miake 3 and Takehiko Fujino4

* Responsible author: mawatari@rheology.po-jp.com
1Institute of Rheological Function of Nutrition, 2241 Kubara, Hisayama-chou, Kasuya-gun, Fukuoka 811-2501, Japan

Full information about the authors is given at the end of the article.
\u00a9 2012 Mawatari et al.; licensee of BioMed Central Ltd. This article is publicly available in accordance with the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0~~HEAD=pobj) , authorizing unlimited use, distribution and reproduction on any medium, provided that the original work is correctly cited.

Abstract

Introduction: many diseases associated with plasmalogen deficiency are known. An increase in the content or substitution of plasmalogens in tissues could have a beneficial effect on the condition of patients suffering from such diseases, but there is no information about the effects of food plasmalogens on mammals.

Method: plasmalogens were obtained from chicken skin. Purified plasmalogens contained 96.4% ethanolamine plasmalogen (PlsEtn), 2.4% choline plasmalogen (PlsCho) and 0.5% sphingomyelin (SM).

Rats were offered a diet containing 0.1% purified plasmalogens (PlsEtn diet). To determine the relative content of phospholipids, the method of high-performance liquid chromatography (HPLC) was used, which allows the separating of intact plasmalogens and all other classes of phospholipids in one chromatographic run.

Results: a consequence of taking the PlsEtn diet, which Zucker rats suffering from diabetes and obesity (ZDF) received for 4 weeks, was a decrease in the level of cholesterol and phospholipids in plasma compared with the control diet.

The results of other standard laboratory plasma tests, including triglyceride and glucose, hepatic and renal function, albumin level and body weight showed no changes. In the group receiving the PlsEtn diet, the relative content of PlsEtn erythrocytes and phosphatidylethanolamine (PE) increased, and the relative content of phosphatidylcholine (PC) decreased.

Taking the PlsEtn diet by healthy rats for 9 weeks also led to a decrease in the level of cholesterol and phospholipids in plasma and caused an increase in the relative content of PlsEtn in the erythrocyte membrane. The results of other standard laboratory tests of plasma and body weight showed no changes.

Conclusions: intake of dietary PlsEtn increases the relative content of PlsEtn in the erythrocyte membrane in healthy rats and ZDF rats and reduces the level of cholesterol and phospholipids in plasma. Taking dietary PlsEtn for 9 weeks did not have a negative effect on the condition of healthy rats.

Keywords: food plasmalogen, Zucker rat suffering from diabetes and obesity, Wistar rat, erythrocyte phospholipids, plasma phospholipids

Introduction

Plasmalogens are glycerophospholipids characterized by a vinyl ester bond at the sn-1 position of the glycerol main chain and an ether bond at the sn-2 position. The position of sn-1 is most often associated with fatty alcohols C16, C18, or C18:1, and the position of sn-2 is usually occupied by polyunsaturated fatty acid, in particular, arachidonic acid (ARA) or docosahexaenoic acid (DHA) [1-5].
Plasmalogens are present in almost all mammalian tissues and account for about 18% of the total volume of phospholipids in cell membranes, and ethanolamine plasmalogens (PlsEtn) are much more common than choline plasmalogens (PlsCho), except cardiac and skeletal muscle tissue [1-5]. Plasmalogens are not only a structural component of the membrane and a repository of secondary intermediaries in mammals but can also participate in the processes of membrane synthesis, ion transfer and cholesterol outflow [1-5].
The vinyl ester bond at the sn-1 position makes plasmalogens more susceptible to oxidative stress compared to the corresponding glycerophospholipids with ether bonds. Therefore, plasmalogens can also act as antioxidants that protect cells from oxidative stress [1-5].

The biosynthesis of plasmalogens begins in peroxisomes, and the hereditary peroxisomal pathology that occurs in humans, rhizomelic point chondrodysplasia (RCDP), manifests itself in a deficiency of plasmalogens in tissues of various organs and causes serious disorders of many tissues and organs, such as the skeleton, brain, lens of the eye, kidneys and heart [2-5]. RCDP may be a direct consequence of plasmalogen deficiency and indicates the importance of plasmalogens in the human body.

At the same time, secondary plasmalogen deficiency is observed in metabolic and inflammatory diseases, such as diabetes mellitus, heart disease, cancer, respiratory diseases and Alzheimer's disease [3,4]. Secondary deficiency of plasmalogens may be a consequence of slowing down the synthesis and/or accelerating the decay of plasmalogens. Replenishment and/or replacement of plasmalogens could bring significant benefits to patients suffering from these diseases with a deficiency of plasmalogens.

Recently, an analysis of data on the effect of food phospholipids on health was performed [6], which showed that according to most studies, food phospholipids have a positive effect on certain diseases without any serious side effects. However, dietary plasmalogens were not mentioned [6].

Plasmalogens were obtained by us from chicken skin. We offered a diet containing 0.1% purified plasmalogens to Zucker rats suffering from diabetes and obesity (ZDF) and healthy Wistar rats. The usual laboratory tests of blood plasma (including the total content of phospholipids) and analysis of the phospholipid composition of plasma and erythrocytes were performed.

Results and analysis

Purified plasmalogens obtained from chicken skin consisted, according to the calculation of the HPLC chromatographic region, of 96.4% ethanolamine plasmalogens (PlsEtn), 2.6% choline plasmalogens (PlsCho), 0.5% SM and 0.7% other phospholipids (Table 1, Fig. 1).

The retention time of chromatographic peaks of PlsEtn and PlsCho corresponded to the retention time of PlsEtn and PlsCho of rat membrane erythrocytes (Fig. 1). The peaks disappeared after treatment with hydrochloric acid (HCl), which means that the peaks corresponded to plasmalogens [7,8] (data not shown). PlsEtn fatty acids consisted of DHA (22:6), ARA (20:4), oleic acid (18:1), myristic acid (14:0), palmitic acid (16:0) and stearic acid (18:0) (Table 1), which corresponds to the composition of conventional plasmalogens in mammalian tissues [1-4].

Table 1 Phospholipid composition of purified plasmalogens and fatty acid composition of PlsEtn in purified plasmalogens

Phospholipid composition	Fatty acid composition Pls Etn
		Fatty acid
PlsEtn	96.4%	14:0	5.4%
PlsCho	2.6%	16:0	7.7%
SM	0.5%	18:0	3.5%
LPE	0.7%	18:1	35.4%
		18:2	9.5%
		20:4	32.7%
		20:4	32.7%
		22:6	6.4%

Purified plasmalogens

Figure 1 HPLC chromatogram of purified plasmalogen from chicken skin. The retention time of ethanolamine plasmalogens (PlsEtn) and choline plasmalogens (PlsCho) corresponded to the rat erythrocyte counts. Other abbreviations: PE, phosphatidylethanolamine; PC, phosphatidylcholine; SM-1 and SM-2, sphingomyelin; PS, phosphatidylserine; PI, phosphatidylinositol.

(Control diet)
(Diet PlsEtn)

Figure 2 HPLC chromatograms of phospholipids in a control diet and a diet enriched with plasmalogens (PlsEtn diet). The chromatogram shows that plasmalogens (PlsEtn and PlsCho) are indeed present in the PlsEtn diet. Abbreviations: see Fig. 1.

The PlsEtn diet, which ZDF rats received for 4 weeks, induced an increase in PlsEtn and PE levels and a decrease in PC levels in erythrocyte membranes (Table 4). The PlsEtn diet, which Wistar rats received for 9 weeks, also induced an increase in PlsEtn levels and a tendency to decrease PC in erythrocyte membranes (Table 7). In the fatty acid composition of PlsEtn + PE, an increase in the ARA content (20:4) and a decrease in the oleic acid content (18:1) were observed (Table 8). An increase in the ARA content in the erythrocyte membrane PlsEtn may reflect the fatty acid composition of PlsEtn in the diet (Table 1). These results of the analysis of erythrocyte membranes indicate that dietary PlsEtn can increase the relative concentration of PlsEtn in tissues.

Table 2.Changes in plasma cholesterol and phospholipids in ZDF rats after 4 weeks on a diet PlsEtn

The chromatogram of the phospholipid analysis of the PlsEtn diet has a large peak PlsEtn compared to the control diet. This means that PlsEtn is indeed contained in the PlsEtn diet (Fig. 2).

A diet containing 0.1% by weight. purified plasmalogens (PlsEtn diet) caused a decrease in plasma phospholipids and cholesterol levels in ZDF rats for 4 weeks (Table 2).