Effects of phosphatidylserine administration of aged-related structural changes in the rat hippocampus and septal complex

Phosphatidylserine, inflammation, and central nervous system diseases

Phosphatidylserine (PS) is an anionic phospholipid in the eukaryotic membrane and is abundant in the brain. Accumulated studies have revealed that PS is involved in the multiple functions of the brain, such as activation of membrane signaling pathways, neuroinflammation, neurotransmission, and synaptic refinement. Those functions of PS are related to central nervous system (CNS) diseases. In this review, we discuss the metabolism of PS, the anti-inflammation function of PS in the brain; the alterations of PS in different CNS diseases, and the possibility of PS to serve as a therapeutic agent for diseases. Clinical studies have showed that PS has no side effects and is well tolerated. Therefore, PS and PS liposome could be a promising supplementation for these neurodegenerative and neurodevelopmental diseases.

Phosphatidylserine and the human brain

OBJECTIVE

The aim of this study was to assess the roles and importance of phosphatidylserine (PS), an endogenous phospholipid and dietary nutrient, in human brain biochemistry, physiology, and function.

METHODS

A scientific literature search was conducted on MEDLINE for relevant articles regarding PS and the human brain published before June 2014. Additional publications were identified from references provided in original papers; 127 articles were selected for inclusion in this review.

RESULTS

A large body of scientific evidence describes the interactions among PS, cognitive activity, cognitive aging, and retention of cognitive functioning ability.

CONCLUSION

Phosphatidylserine is required for healthy nerve cell membranes and myelin. Aging of the human brain is associated with biochemical alterations and structural deterioration that impair neurotransmission. Exogenous PS (300-800 mg/d) is absorbed efficiently in humans, crosses the blood-brain barrier, and safely slows, halts, or reverses biochemical alterations and structural deterioration in nerve cells. It supports human cognitive functions, including the formation of short-term memory, the consolidation of long-term memory, the ability to create new memories, the ability to retrieve memories, the ability to learn and recall information, the ability to focus attention and concentrate, the ability to reason and solve problems, language skills, and the ability to communicate. It also supports locomotor functions, especially rapid reactions and reflexes.

A randomized controlled trial investigating the neurocognitive effects of Lacprodan® PL-20, a phospholipid-rich milk protein concentrate, in elderly participants with age-associated memory impairment: the Phospholipid Intervention for Cognitive Ageing Reversal (PLICAR): study protocol for a randomized controlled trial

BACKGROUND

Age-related cognitive decline (ARCD) is of major societal concern in an ageing population, with the development of dietary supplements providing a promising avenue for amelioration of associated deficits. Despite initial interest in the use of phospholipids (PLs) for ARCD, in recent years there has been a hiatus in such research. Because of safety concerns regarding PLs derived from bovine cortex, and the equivocal efficacy of soybean-derived PLs, there is an important need for the development of new PL alternatives. Phospholipids derived from milk proteins represent one potential candidate treatment.

METHODS

In order to reduce the effects of age-associated memory impairment (AAMI) the Phospholipid Intervention for Cognitive Ageing Reversal (PLICAR) was developed to test the efficacy of a milk protein concentrate rich in natural, non-synthetic milk phospholipids (Lacprodan® PL-20). PLICAR is a randomized, double-blind, placebo-controlled parallel-groups study where 150 (N = 50/group) AAMI participants aged > 55 years will be randomized to receive a daily supplement of Lacprodan® PL-20 or one of two placebos (phospholipid-free milk protein concentrate or inert rice starch) over a 6-month (180-day) period. Participants will undergo testing at baseline, 90 days and 180 days. The primary outcome is a composite memory score from the Rey Auditory Verbal Learning Test. Secondary outcomes include cognitive (verbal learning, working memory, prospective and retrospective memory, processing speed and attention), mood (depression, anxiety, stress and visual analogue scales), cardiovascular (blood pressure, blood velocity and pulse wave pressure), gastrointestinal microbiota and biochemical measures (oxidative stress, inflammation, B vitamins and Homocysteine, glucoregulation and serum choline). Allelic differences in the Apolipoprotein E and (APOE) and Methylenetetrahydrofolate reductase (MTHFR) gene will be included for subgroup analysis. A subset (N = 60; 20/group)) will undergo neuroimaging using functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG) in order to further explore in vivo central mechanisms of action of Lacprodan® PL-20. This study will enable evaluation of the efficacy of milk-derived phospholipids for AAMI, and their mechanisms of action.

TRIAL REGISTRATION

The trial is jointly funded by Arla Foods and Swinburne University of Technology, currently recruiting and is registered on the Australian New Zealand Clinical Trials Registry as ACTRN12613000347763.

n-3, but not n-6 lipid particle uptake requires cell surface anchoring

Omega-3 (n-3) fatty acids are emerging as bioactive agents protective against cardiovascular disease. However, their cellular delivery pathways are poorly defined. Here we questioned whether the uptake of n-3 triglyceride-rich particles (TGRP) is mediated by cell surface proteoglycans (PG) using LDL receptor (LDLR)+/+ and LDLR-/- cell models. LDLR+/+ but not LDLR-/- cells showed higher n-6 over n-3 TGRP uptake. Removal of cell surface proteins and receptors by pronase markedly enhanced the uptake of n-3 but not n-6 TGRP. Lactoferrin blockage of apoE-mediated pathways decreased the uptake of n-6 TGRP by up to 85% (p<0.05) but had insignificant effect on n-3 TGRP uptake. PG removal by sodium chlorate in LDLR+/+ cells substantially reduced n-3 TGRP uptake but had little effect on n-6 TGRP uptake. Thus, while n-6 TGRP uptake is preferentially mediated by LDLR-dependent pathways, the uptake of n-3 TGRP depends more on PG and non-LDLR cell surface anchoring.

Omega-3 fatty acids: molecular approaches to optimal biological outcomes

PURPOSE OF REVIEW

This review discusses recent advances in delineating basic mechanisms underlying the beneficial effects of omega-3 fatty acids on health and on disease.

RECENT FINDINGS

While a substantial number of studies have delineated many differences between the biological effects of saturated versus polyunsaturated fatty acids, less is known about the long-chain omega-3 fatty acids commonly present in certain fish oils. In this review, we focus on recent studies relating to basic mechanisms whereby omega-3 fatty acids modulate cellular pathways to exert beneficial effects on promoting health and decreasing risks of certain diseases. We will use, as examples, conditions of the cardiovascular, neurological, and immunological systems as well as diabetes and cancer, and then discuss basic regulatory pathways.

SUMMARY

Omega-3 fatty acids are major regulators of multiple molecular pathways, altering many areas of cellular and organ function, metabolism and gene expression. Generally, these regulatory events lead to "positive" endpoints relating to health and disease.

Neuroprotective effect of developmental docosahexaenoic acid supplement against excitotoxic brain damage in infant rats

Long-chain polyunsaturated fatty acid (LC-PUFA) composition of neural membranes is a key factor for brain development, in chemical communication of neurons and probably also their survival in response to injury. Viability of cholinergic neurons was tested during brain development following dietary supplementation of fish oil LC-PUFAs (docosahexaenoic acid [DHA], eicosapentaenoic acid, arachidonic acid) in the food of mother rats. Excitotoxic injury was introduced by N-methyl-D,L-aspartate (NMDA) injection into the cholinergic nucleus basalis magnocellularis of 14-day-old rats. The degree of loss of cholinergic cell bodies, and the extend of axonal and dendritic disintegration were measured following immunocytochemical staining of cell bodies and dendrites for choline acetyltransferase and p75 low-affinity neurotrophin receptor and by histochemical staining of acetylcholinesterase-positive fibres in the parietal neocortex. The impact of different feeding regimens on fatty acid composition of neural membrane phospholipids was also assayed at 12 days of age. Supplementation of LC-PUFAs resulted in a resistance against NMDA-induced excitotoxic degeneration of cholinergic neurones in the infant rats. More cholinergic cells survived, the dendritic involution of surviving neurons in the penumbra region decreased, and the degeneration of axons at the superficial layers of parietal neocortex also attenuated after supplementing LC-PUFAs. A marked increment in DHA content in all types of phospholipids was obtained in the forebrain neuronal membrane fraction of supplemented rats. It is concluded that fish oil LC-PUFAs, first of all DHA, is responsible for the neuroprotective action on developing cholinergic neurons against glutamate cytotoxicity.

Differential spine loss and regrowth of striatal neurons following multiple forms of deafferentation: a Golgi study

Golgi-Cox method and morphometric analyses were used to study the plasticity of striatal medium spiny I neurons in 6-month-old C57BL/6N mice after unilateral or bilateral lesion of the cerebral cortex or combined lesions of the ipsilateral cerebral cortex and intralaminar thalamus. In adult mouse, unilateral lesions of the cerebral cortex did not result in a net gain or loss of linear dendritic length in a randomly selected population of striatal medium spiny I neurons. In addition, there was a well-defined time course of striatal spine loss and replacement occurring after a unilateral cortical lesion. By day 3 postlesion the average 20-microm dendritic segment had lost 30% of the unlesioned control spine value, reached its nadir, lost 45.5%, at 10 days postlesion, and recovered to 80% of unlesioned control levels by 20 days postlesion. The recovery of spines was blocked by a secondary lesion on the contralateral cortex but not on the ipsilateral intralaminar thalamus. These data suggest that striatal medium spiny I neurons of adult mice have a remarkable capacity for plasticity and reactive synaptogenesis following a decortication. The recovery of spine density is primarily induced by axonal sprouting of survival homologous afferent fibers from the contralateral cortex.

Chronic administration of a partial muscarinic M1 receptor agonist attenuates decreases in forebrain choline acetyltransferase immunoreactivity following experimental brain trauma

Lu 25-109-T is a partial muscarinic M1 receptor agonist with antagonistic effects at presynaptic M2 autoreceptors and has been shown to improve cognitive function following traumatic brain injury (TBI) in rats. This investigation examined the effects of TBI on basal forebrain choline acetyltransferase immunoreactivity (ChAT-IR) following daily administration of saline or 15 mumol/kg Lu 25-109-T. Rats received a moderate (2.1 +/- 0.1 atm) level of central fluid percussion TBI or were surgically prepared but not injured and were injected (sc) with saline or drug on Days 1-15 postinjury. Rats were sacrificed following the last daily injection, and sections were collected through the basal forebrain and processed for ChAT-IR. TBI caused a significant reduction in ChAT-IR neuronal density in saline- and Lu 25-109-T-treated rats with a 13% and 5% decrease in the medial septal nucleus (MSN), a 48 and 23% decrease in the vertical limb nucleus of the diagonal band (VDB), and a 51 and 28% decrease in the nucleus basalis magnocellularis (NBM), respectively. However, Lu 25-109-T significantly attenuated the injury-induced reductions in ChAT-IR. Loss in ChAT-IR neuronal density is not thought to result from cell death as parallel cresyl violet-stained sections indicated no decrease in neuronal cell density in the MSN, VDB, or NBM. These results support the hypothesis that increasing cholinergic tone during the recovery period after TBI will restore cholinergic function impaired by brain trauma.

Choline acetyltransferase and acetylcholinesterase in the hippocampus of aged rats: sensitivity to choline alphoscerate treatment

The influence of aging on the acetylcholine synthesising and the degrading enzymes choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) was studied in the hippocampus of male Wstar rats at 2 months (young), 12 months (adult) and 27 months (old) of age using biochemical, immunocytochemical and histochemical techniques. The influence of treatment for 6 months with a daily dose of 100 mg/kg of choline alphoscerate (L-alpha-glycerylphosphorylcholine) on the parameters examined was also investigated in old rats. Biochemical analysis of ChAT and AChE revealed the highest of the enzymatic activities in the hippocampus of adult rats and no significant differences between young and old animals. Immunocytochemical analysis of ChAT immunoreactivity revealed the highest immunostaining in adult rats followed in descending order by young then old animals. Histochemical evaluation of AChE reactivity revealed the highest expression in adult rats followed in descending order by old then young animals. Biochemical analysis of the effects of choline alphoscerate did not reveal any effect on ChAT activity and in increased expression of AChE activity. Moreover, the compound restored, in part, ChAT immunoreactivity in the hippocampus of old rats and increased the expression of AChE reactivity primarily in the CA3 sub field in old rats. The above results suggest that appropriate quantitative immunocytochemical and histochemical techniques may represent a useful tool for assessing age-dependent changes in cholinergic neurotransmission markers. The functional and pharmacological significance of the effects of choline alphoscerate on the expression of ChAT and AChE in the hippocampus of aged rats should be clarified in future studies.

A quantitative study of the perikaryon and the basal dendritic tree in rat hippocampus (CA1) pyramids following different experimental procedures

A quantitative study of perikaryon and basal dendritic branching of hippocampal (CA1) neurons in male Wistar rats, in three experimental groups is reported. The groups of animals were exposed to treatment with either a tricyclic antidepressant, or a saline control injection or no handling. The hippocampal tissue was studied following Golgi-Kopsch impregnation and comparative measurements made using semi-automatic image analysis and light microscopy. Measurements of the extent of basal dendritic branching showed a significant difference (p < 0.01) between the saline-injected and unhandled control groups. The drug-injected and saline-injected groups had similar values although the drug-injected group did not prove to be significantly different from the unhandled controls. No statistical difference was noted in the perikaryon size of the three experimental groups. These results are discussed with reference to the effects of sensory stimulation on neuronal plasticity.