Effect of phosphatidylserine on acetylcholine output from the cerebral cortex of the rat

Milk Fat Globule Membranes for Mental Health across the Human Lifespan

The milk fat globule membrane (MFGM) contains bioactive proteins, carbohydrates, and lipids. Polar lipids found in the MFGM play a critical role in maintaining cell membrane integrity and neuronal signalling capacity, thereby supporting brain health. This review summarises the literature on the MFGM and its phospholipid constituents for improvement of mental health across three key stages of the human lifespan, i.e., infancy, adulthood, and older age. MFGM supplementation may improve mental health by reducing neuroinflammation and supporting neurotransmitter synthesis through the gut-brain axis. Fortification of infant formula with MFGMs is designed to mimic the composition of breastmilk and optimise early gut and central nervous system development. Early behavioural and emotional development sets the stage for future mental health. In adults, promising results suggest that MFGMs can reduce the negative consequences of situational stress. Preclinical models of age-related cognitive decline suggest a role for the MFGM in supporting brain health in older age and reducing depressive symptoms. While there is preclinical and clinical evidence to support the use of MFGM supplementation for improved mental health, human studies with mental health as the primary target outcome are sparce. Further high-quality clinical trials examining the potential of the MFGM for psychological health improvement are important.

Effects of ethanol extract from Bidens pilosa L. on spontaneous activity, learning and memory in aged rats

BACKGROUND

Bidens pilosa L., a herbal medicine, is rich in flavonoids, but its anti-aging effect on neurocognitive functions is not well understood. In the present study, we investigated the effects of ethanol extract from Bidens pilosa L. (EEBP) on spontaneous activity, learning and memory in aged rats.

METHODS

Forty aged (21.90 ± 0.22 months) and 10 young (10 weeks) adult male Sprague-Dawley rats were divided into 5 groups, which were respectively treated orally with 0 mg/kg (young and aged control), 25 mg/kg, 50 mg/kg and 100 mg/kg of EEBP for 30 days consecutively. Then, the animals were examined with open-field, passive avoidance and Morris water maze tasks.

RESULTS

In the open-field task, compared with the aged control, the EEBP animals exhibited more rearing (50 mg/kg, P < 0.01) and urination (50 mg/kg, P < 0.01), but less defecation (P < 0.05). In the passive avoidance task, the retention latencies were longer than those in the training phase in all other groups (P < 0.01) except the aged control (P > 0.05). Compared with the young control, the retention latency of the aged control decreased (P < 0.01), but that of the EEBP animals increased again (P < 0.05 vs. aged control). In the Morris water maze, the EEBP animals had shorter latency (100 mg/kg) and had more crossing times (25 mg/kg) in seeking the platform position (P < 0.05, vs. aged control).

CONCLUSION

The results suggested that EEBP could affect the spontaneous activity and improve memory in aged animals and could have potential advantages for cognition improvement in aged populations.

Effects of milk-based phospholipids on cognitive performance and subjective responses to psychosocial stress: A randomized, double-blind, placebo-controlled trial in high-perfectionist men

OBJECTIVES

The aim of this study was to examine the stress-buffering potential of phospholipid (PL) intake on cognitive performance and neuroendocrine and psychological responses under conditions of psychosocial stress in a high-stress vulnerable (perfectionist) sample.

METHODS

Fifty-four high-perfectionist men consumed a 6-wk daily intake of a bovine milk-derived PL (2.7 g/d) or placebo drink in a randomized, double-blind, placebo-controlled, parallel groups design. Working memory, executive control function, and acute physiological/subjective responses to an acute psychosocial stressor were examined before and after the 6-wk PL or placebo intake.

RESULTS

PL intake improved post-stress reaction time performance on an attention-switching task (P = 0.01). No significant attenuation of the salivary cortisol stress response was shown. PL intake significantly increased mid-stress induction energetic arousal (P = 0.03). A non-significant reduction in anticipatory subjective stress was reported after PL intake (P = 0.06). Systolic and diastolic blood pressures (P<0.04 and P = 0.01, respectively) were significantly augmented in the PL condition.

CONCLUSIONS

Dietary intake of bovine milk PLs conferred cognitive performance benefit under conditions of psychosocial stress but failed to moderate cortisol response. Moderation of subjective response to stress exposure may have underpinned this performance protection.

The Effects of Phosphatidylserine and Omega-3 Fatty Acid-Containing Supplement on Late Life Depression

Late life depression is often associated with a poor response to antidepressants; therefore an alternative strategy for therapy is required. Although several studies have reported that phosphatidylserine (PS) may be effective for late life depression and that omega-3 fatty acids DHA and EPA have also proven beneficial for many higher mental functions, including depression, no concrete conclusion has been reached. This study was performed to clarify the effect of PS and omega-3 fatty acid-containing supplement for late life depression by not only clinical evaluation but also salivary cortisol levels. Eighteen elderly subjects with major depression were selected for the study. In all, insufficient improvement had been obtained by antidepressant therapy for at least 6 months. The exclusion criteria from prior brain magnetic resonance images (MRI) included the presence of structural MRI findings compatible with stroke or other gross brain lesions or malformations, but not white matter hypersensitivities. They took a supplement containing PS 100 mg, DHA 119 mg and EPA 70 mg three times a day for 12 weeks. The effects of the supplement were assessed using the 17-item Hamilton depression scale (HAM-D17) and the basal levels and circadian rhythm of salivary cortisol. The study adopted them as indices because: salivary cortisol levels are high in patients with depression, their circadian rhythm related to salivary cortisol is often irregular, and these symptoms are alleviated as depression improves. The mean HAM-D17 in all subjects taking the supplement was significantly improved after 12 weeks of taking the supplement. These subjects were divided into 10 non-responders and 8 responders. The basal levels and circadian rhythm of salivary cortisol were normalized in the responders while not in non-responders. PS and omega-3 fatty acids, or other elements of the supplement, may be effective for late life depression, associated with the correction of basal levels and circadian rhythm of salivary cortisol.

Oral administration of squid lecithin-transphosphatidylated phosphatidylserine improves memory impairment in aged rats

Recently, lecithin-derived phosphatidylserine (PS), which originates from marine life, has received much attention as a viable alternative to bovine cerebral cortex PS. In this study, the use of squid phosphatidylcholine-transphosphatidylated PS (SQ-PS) was evaluated through examination of its ameliorating effects on age-associated learning and memory deficits in rats. Aged rats were orally administered SQ-PS (10, 20, or 50 mg/kg per day) once a day for seven days 30 min prior to behavioral assessment in a Morris water maze. SQ-PS administration produced significant dose-dependent improvements in escape latency for finding the platform in the Morris water maze in the aged rats even though Soy-PS administration also exhibited comparable improvements with SQ-PS. Biochemical alterations in the hippocampal cholinergic system, including changes in choline acetyltransferase and acetylcholinesterase immunoreactivity, were consistent with the behavioral results. In addition, SQ-PS treatment significantly restored age-associated decreases of choline transporter and muscarinic acetylcholine receptor type 1 mRNA expression in the hippocampus. These results demonstrate that orally administered SQ-PS dose-dependently aids in the improvement of memory deficits that occur during normal aging in rats. This suggests that SQ-PS may be a useful therapeutic agent in the treatment of diminished memory function in elderly people.

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.

Phosphatidylserine in the brain: metabolism and function

Phosphatidylserine (PS) is the major anionic phospholipid class particularly enriched in the inner leaflet of the plasma membrane in neural tissues. PS is synthesized from phosphatidylcholine or phosphatidylethanolamine by exchanging the base head group with serine, and this reaction is catalyzed by phosphatidylserine synthase 1 and phosphatidylserine synthase 2 located in the endoplasmic reticulum. Activation of Akt, Raf-1 and protein kinase C signaling, which supports neuronal survival and differentiation, requires interaction of these proteins with PS localized in the cytoplasmic leaflet of the plasma membrane. Furthermore, neurotransmitter release by exocytosis and a number of synaptic receptors and proteins are modulated by PS present in the neuronal membranes. Brain is highly enriched with docosahexaenoic acid (DHA), and brain PS has a high DHA content. By promoting PS synthesis, DHA can uniquely expand the PS pool in neuronal membranes and thereby influence PS-dependent signaling and protein function. Ethanol decreases DHA-promoted PS synthesis and accumulation in neurons, which may contribute to the deleterious effects of ethanol intake. Improvement of some memory functions has been observed in cognitively impaired subjects as a result of PS supplementation, but the mechanism is unclear.

The effect of phosphatidylserine administration on memory and symptoms of attention-deficit hyperactivity disorder: a randomised, double-blind, placebo-controlled clinical trial

BACKGROUND

Attention-deficit hyperactivity disorder (ADHD) is the most commonly diagnosed behavioural disorder of childhood, affecting 3-5% of school-age children. The present study investigated whether the supplementation of soy-derived phosphatidylserine (PS), a naturally occurring phospholipid, improves ADHD symptoms in children.

METHODS

Thirty six children, aged 4-14 years, who had not previously received any drug treatment related to ADHD, received placebo (n = 17) or 200 mg day(-1) PS (n = 19) for 2 months in a randomised, double-blind manner. Main outcome measures included: (i) ADHD symptoms based on DSM-IV-TR; (ii) short-term auditory memory and working memory using the Digit Span Test of the Wechsler Intelligence Scale for Children; and (iii) mental performance to visual stimuli (GO/NO GO task).

RESULTS

PS supplementation resulted in significant improvements in: (i) ADHD (P < 0.01), AD (P < 0.01) and HD (P < 0.01); (ii) short-term auditory memory (P < 0.05); and (iii) inattention (differentiation and reverse differentiation, P < 0.05) and inattention and impulsivity (P < 0.05). No significant differences were observed in other measurements and in the placebo group. PS was well-tolerated and showed no adverse effects.

CONCLUSIONS

PS significantly improved ADHD symptoms and short-term auditory memory in children. PS supplementation might be a safe and natural nutritional strategy for improving mental performance in young children suffering from ADHD.

Krill phosphatidylserine improves learning and memory in Morris water maze in aged rats

The ameliorating effect of phosphatidylserine (PS) isolated from krill (KR-PS) on the learning and memory deficits associated with normal aging in rats was investigated, as compared with soybean PS (SOY-PS). Rats were orally administered with KR-PS (20, 50 mg kg-1) and SOY-PS (50 mg kg-1) daily, for 7 days, 30 min before behavioral assessment using the Morris water maze (MWM). Changes in the cholinergic system were examined by measuring choline acetyltransferase (ChAT) and acetylcholinesterase (AchE) immunoreactivity in the hippocampus. The daily administration of KR-PS produced a significant improvement in the escape latency for finding the platform in the MWM, as compared with SOY-PS. Consistent with the behavioral results, KR-PS treatments significantly alleviated age-associated losses of cholinergic immunoreactivity, and muscarinic acetylcholine receptor type 1 (mAChR-M1) and choline transporter (CHT) mRNA expression in the hippocampus. These findings demonstrate that KR-PS showed significant neuroprotective activity against the neuronal and cognitive impairments that occur with normal aging in rats; comparable results were obtained with SOY-PS. These data indicate that oral administration of PS derived from marine life could substitute for bovine cerebral cortex PS (BC-PS) as therapy for the improvement of diminished memory function in elderly people.

Comparison of molecular species of various transphosphatidylated phosphatidylserine (PS) with bovine cortex PS by mass spectrometry

The exogenous introduction of a molecular species mixture of bovine cortex phosphatidylserine (BC-PS) has been claimed to improve memory function in subjects suffering from age-associated memory impairment and dementia. However, it has been also reported that oral administration of another molecular species mixture of transphosphatidylated-soybean phosphatidylserine (T-Soy-PS) showed a little effect in older individuals with memory complaints. In this study, a new type of mixture of transphosphatidylated-fish liver phosphatidylserine (T-FL-PS) species, as well as intact molecular species of the two commercial products of T-Soy-PS made in the United States and Europe, were characterized by mass spectrometry and tandem mass spectrometry, and molecular species of various transphosphatidylated PSs, including T-FL-PS, T-Soy-PS and transphosphatidylated-squid skin phosphatidylserine (T-SS-PS) were then compared with those of BC-PS for the first time. The results show that (i) the presence of a relatively high content of docosahexaenoic acid (DHA)-containing species (more than 45%) is remarkable in T-FL-PS, (ii) DHA-ether PS species are found only in T-FL-PS, especially the species (about 17%) made from marine fish liver, rather than BC-PS and T-SS-PS, and (iii) DHA species present in both T-FL-PS and T-SS-PS are significantly enriched, compared with those in BC-PS (about 10%) and T-Soy-PS (no DHA species). We conclude that mixtures of T-FL-PS and T-SS-PS species are considered to be qualified alternatives of BC-PS supplement used as brain nutrients. It is expected that intact structural information on molecular species in current and potential transphosphatidylated PS products provided here will be useful in the further study and development of therapeutic roles of the phospholipid at molecular species level.

Effects of phosphatidylserine supplementation on exercising humans

Phosphatidylserine (PtdSer) is a ubiquitous phospholipid species that is normally located within the inner leaflet of the cell membrane. PtdSer has been implicated in a myriad of membrane-related functions. As a cofactor for a variety of enzymes, PtdSer is thought to be important in cell excitability and communication. PtdSer has also been shown to regulate a variety of neuroendocrine responses that include the release of acetylcholine, dopamine and noradrenaline. Additionally, PtdSer has been extensively demonstrated to influence tissue responses to inflammation. Finally, PtdSer has the potential to act as an effective antioxidant, especially in response to iron-mediated oxidation. The majority of the available research that has investigated the effects of PtdSer supplementation on humans has concentrated on memory and cognitive function; patients experiencing some degree of cognitive decline have traditionally been the main focus of investigation. Although investigators have administered PtdSer through intravenous and oral routes, oral supplementation has wider appeal. Indeed, PtdSer is commercially available as an oral supplement intended to improve cognitive function, with recommended doses usually ranging from 100 to 500 mg/day. The main sources that have been used to derive PtdSer for supplements are bovine-cortex (BC-PtdSer) and soy (S-PtdSer); however, due to the possibility of transferring infection through the consumption of prion contaminated brain, S-PtdSer is the preferred supplement for use in humans. Although the pharmacokinetics of PtdSer have not been fully elucidated, it is likely that oral supplementation leads to small but quantifiable increases in the PtdSer content within the cell membrane.A small number of peer-reviewed full articles exist that investigate the effects of PtdSer supplementation in the exercising human. Early research indicated that oral supplementation with BC-PtdSer 800 mg/day moderated exercise-induced changes to the hypothalamo-pituitary-adrenal axis in untrained participants. Subsequently, this finding was extended to suggest that S-PtdSer 800 mg/day reduced the cortisol response to overtraining during weight training while improving feeling of well-being and decreasing perceived muscle soreness. However, equivocal findings from our laboratory might suggest that the dose required to undertake this neuroendocrine action may vary between participants.Interestingly, recent findings demonstrating that short-term supplementation with S-PtdSer 750 mg/day improved exercise capacity during high-intensity cycling and tended to increase performance during intermittent running might suggest an innovative application for this supplement. With the findings from the existing body of literature in mind, this article focuses on the potential effects of PtdSer supplementation in humans during and following exercise.

Choline alphoscerate in cognitive decline and in acute cerebrovascular disease: an analysis of published clinical data

This paper has reviewed the documentation on the clinical efficacy of choline alphoscerate, a cholinergic precursor, considered as a centrally acting parasympathomimetic drug in dementia disorders and in acute cerebrovascular disease. Thirteen published clinical trials, examining in total 4054 patients, have evaluated the use of choline alphoscerate in various forms of dementia disorders of degenerative, vascular or combined origin, such as senile dementia of the Alzheimer's type (SDAT) or vascular dementia (VaD) and in acute cerebrovascular diseases, such as transitory ischemic attack (TIA) and stroke. Analysis has assessed the design of each study, in particular with respect to experimental design, number of cases, duration of treatment and tests used to evaluate drug clinical efficacy. Most of the ten studies performed in dementia disorders were controlled trials versus a reference drug or placebo. Overall, 1570 patients were assessed in these studies, 854 of which in controlled trials. As detected by validated and appropriate tests, such as Mini Mental State Evaluation (MMSE) in SDAT and Sandoz Clinical Assessment Geriatric (SCAG) in VaD, administration of choline alphoscerate significantly improved patient clinical condition. Clinical results obtained with choline alphoscerate were superior or equivalent to those observed in control groups under active treatment and superior to the results observed in placebo groups. Analysis stresses the clear internal consistency of clinical data gathered by different experimental situations on the drug effect, especially with regard to the cognitive symptoms (memory, attention) characterising the clinical picture of adult-onset dementia disorders. The therapeutic usefulness of choline alphoscerate in relieving cognitive symptoms of chronic cerebral deterioration differentiates this drug from cholinergic precursors used in the past, such as choline and lecithin. Three uncontrolled trials were performed with choline alphoscerate in acute cerebrovascular stroke and TIA, totalling 2484 patients. The results of these trials suggest that this drug might favour functional recovery of patients with cerebral stroke and should be confirmed in future investigations aimed at establish the efficacy of the drug in achieving functional recovery of patients with acute cerebrovascular disease.

The influence of soy-derived phosphatidylserine on cognition in age-associated memory impairment

Phosphatidylserine (PS) is a phospholipid widely sold as a nutritional supplement. PS has been claimed to enhance neuronal membrane function and hence cognitive function, especially in the elderly. We report the results of a clinical trial of soybean-derived PS (S-PS) in aging subjects with memory complaints. Subjects were 120 elderly (> 57 years) of both sexes who fulfilled the more stringent criteria for age-associated memory impairment (AAMI); some also fulfilled the criteria for age-associated cognitive decline. Subjects were allocated at random to one of the three treatment groups: placebo, 300mg S-PS daily, or 600mg S-PS daily. Assessments were carried out at baseline, after 6 and 12 weeks of treatment, and after a wash-out period of 3 weeks. Tests of learning and memory, choice reaction time, planning and attentional functions were administered at each assessment. Delayed recall and recognition of a previously learned word list comprised the primary outcome measures. No significant differences were found in any of the outcome variables between the treatment groups. There were also no significant interactions between treatment and 'severity of memory complaints'. In conclusion, a daily supplement of S-PS does not affect memory or other cognitive functions in older individuals with memory complaints.

Differential incorporation of precursor moieties into cerebral cortex and cerebellum glycerophospholipids during aging

The incorporation of polar and non-polar moieties into cerebral cortex (CC) and cerebellum (CRBL) phospholipids of adult (3.5-month-old) and aged (21.5-month-old) rats was studied in a minced tissue suspension. The biosynthesis of acidic phospholipids through [3H]glycerol appears to be slightly increased with respect to that of zwitterionic or neutral lipids in CC of aged rats with respect to adult rats. On the contrary, the synthesis of phosphatidylcholine (PC) from [3H]choline was inhibited. However, the incorporation of [14C]serine into phosphatidylserine (PS) was higher in CC and CRBL in aged rats with respect to adult rats. The synthesis of phosphatidylethanolamine (PE) from PS was not modified during aging. Saturated ([3H]palmitic) and polyunsaturated ([3H]arachidonic) acids were incorporated successfully by adult and aged brain lipids. In addition [3H]palmitic, [3H]oleic and [3H]arachidonic acid were employed as glycerolipid precursors in brain homogenate from aged (28.5 month old) and adult (3.5 month old) rats. [3H]oleic acid incorporation into neutral lipids (NL) and [3H]arachidonic acid incorporation into PC, PE and phosphatidylinositol (PI) were increased in aged rats with respect to adult rats. Present results show the ability and avidity of aged brain tissue in vitro to incorporate unsaturated fatty acids when they are supplied exogenously. They also suggest a different handling of choline and serine by base exchange enzyme activities to synthesize PC and PS during aging.

Analysis of the mechanisms underlying the age-related impairment in long-term potentiation in the rat

The process of ageing is common to all organisms but despite its universality, understanding of the cellular and molecular changes which accompany ageing is poor. With the increase in the ageing population, the need for systematic study of the process becomes a priority but the development of a systematic approach to the problem requires the development of a testable theory of ageing. While several theories of ageing have been proposed /336/, between which there is at least some overlap, no generally-accepted theory has been identified. In relation to the brain, four interrelated theories of ageing have received significant attention; these are (1) the membrane hypothesis, (2) the free radical hypothesis, (3) the calcium hypothesis and (4) the glucocorticoid theory. The overlap between these hypotheses is such that a causal relationship between them is very likely with age-related changes in membrane composition triggered by changes in free radical production, while changes in membrane composition are likely to account for changes in membrane function including age-related changes in calcium homeostasis. The glucocorticoid theory could equally well be termed the stress hypothesis of ageing, which in the hippocampus at least, might trigger age-related changes in free radical production. This review is not intended to be a balanced appraisal of each theory but emphasizes aspects of the membrane hypothesis of ageing and discusses some relevant aspects of the other hypotheses. Attention is focussed on analysis of the biochemical changes which might underlie age-related changes in hippocampal function, particularly maintenance of long-term potentiation (LTP), and these changes are discussed in the context of the four hypotheses of ageing.

Ethanol alters brain phospholipid levels which correlate with altered brain morphology

The effects of embryonic exposure on brain phospholipid levels were studied by injecting various concentrations of ethanol into fertile chicken eggs at 0 days of development. At 18 days of development, the levels of total phospholipids and various phospholipid classes were assayed in brain tissue and correlated to neuron densities within the cerebral hemispheres and the optic lobes. Although ethanol concentrations ranging from 0 to 3700 microns/Kg egg wt. failed to influence either total brain weight or total brain phospholipid levels, ethanol-induced changes in the levels of individual phospholipid classes were observed. When injected with 7 microns of ethanol/Kg egg wt., a 2- to 3-fold increase in brain phosphatidylethanolamine (PE) levels were observed with reduced levels of brain phosphatidylcholine (PC) and brain sphingomyelin (SP). When injected with 74 microns of ethanol/Kg egg wt., ethanol-induced increases in brain phosphatidylserine (PS) and PE were observed with ethanol-induced decreases in brain PC and SP. Cell fractionation studies demonstrated ethanol-induced increases in brain PE and PS and ethanol-induced decreases in brain PC and SP in nuclear, mitochondrial, and microsomal membranes. These ethanol-induced alterations in brain phospholipid profiles correlated with ethanol-induced reductions in neuron densities within the cerebral hemispheres and optic lobes.

Differential susceptibility of senile and lesion-induced astrogliosis to phosphatidylserine

The susceptibility of age- and lesion-induced astrogliosis to the treatment with phosphatidylserine was investigated with the use of GFAP immunoblotting. The existence of age-induced upregulation of GFAP content was confirmed in the hippocampus, septum, and corpus callosum of the rat. The Ptd-Ser treatment of the aged rats further increased the GFAP content in the hippocampus and corpus callosum. The GFAP content increase in the corpus callosum was additionally illustrated by the upregulation in GFAP immunostaining. In the septum no further elevation of GFAP was observed after Ptd-Ser treatment, and in the striatum the compound elicited significant GFAP content increase, absent in the untreated aged rat brain striatum. In the intact adult rat brain no effect of Ptd-Ser on GFAP content was observed; neither did the compound elicit any modulation of the astrogliosis related to the mechanical lesion of the brain in the septum, hippocampus, cortex, and striatum. In the corpus callosum, Ptd-Ser potentiated the GFAP content increase related to the mechanical lesion, pointing to the structure-related heterogeneity of astrocytic population. Because it has been previously found that Ptd-Ser partly reverses one of the aspects of rodent brain aging, the aging-induced decrease of the acetylcholine release, the possibility exists that the effects of Ptd-Ser administration on glia and neurons in the aged brain may be related.

Neural membrane phospholipids in Alzheimer disease

Phospholipids form the backbone of neural membranes, providing fluidity and permeability. Two plasma membrane fractions, one from synaptosomes (SPM), the other from glial and neuronal cell bodies (PM), were prepared from different regions of autopsied Alzheimer disease (AD) brains. Corresponding fractions were prepared from age-matched control brains. All fractions from AD brains showed significantly lower levels of ethanolamine glycerophospholipids and significantly higher levels of serine glycerophospholipids than the control brain. No differences were observed in phosphatidylcholine levels among these membranes. These results suggest that altered phospholipid composition of plasma membranes may be involved in the abnormal signal transduction and neurodegeneration in AD.

Effect of phosphatidylserine on free radical susceptibility in human diploid fibroblasts

We studied the effect of phosphatidylserine (PdtSER) on oxygen metabolite toxicity in skin fibroblast cell lines from apparently normal subjects. Fibroblast damage was produced by the generation of oxygen metabolites during the enzymatic oxidation of acetaldehyde by xanthine-oxidase (Xo). In order to quantify cell damage, we measured lactate dehydrogenase (LDH) activity in culture medium and cell viability in fibroblast cultures, with and without preincubation for 4 days with PdtSER 13 microM, after Xo incubation. We found a significant increase of LDH activity in culture medium of cells without preincubation with PdtSER. No significant increase of LDH activity was observed in the same cell lines after preincubation with PdtSER.

Phosphatidylserine increases hippocampal synaptic efficacy

In the present study, the effects of phosphatidylserine (BC-PS) on hippocampal synaptic transmission were evaluated. Extracellular potentials evoked by low-frequency stimulation (0.2 Hz) of the perforant path (PP) were recorded from the granule cell layer of the dentate gyrus in 400 microns hippocampal slices. Slices were perfused with either BC-PS alone (10 microM) or BC-PS in combination with DL-2-amino-5-phosphonovaleric acid (APV, 20 microM), or after previous perfusion with dizocilpine (MK-801, 10 microM). BC-PS significantly potentiated PP-evoked responses (mean percent increase +/- SEM, 108 +/- 18%), an effect that was blocked by perfusion of MK-801, but not APV. The increase in hippocampal synaptic efficacy produced by BC-PS is discussed in terms of N-methyl-D-aspartate receptors (NMDA) and the associated channels.

Protective action of phosphatidylserine on stress-induced behavioral and autonomic changes in aged rats

Phosphatidylserine (PS) was administered in aged rats subjected to various stressor stimuli in order to evaluate its effect on grooming behavior, core temperature and gastric ulcers. Novelty-induced grooming appeared to be increased in aged rats as compared to young controls. The subchronic intraperitoneal treatment with PS (20 mg/kg/day for 20 days) decreased grooming activity in aged rats, whereas it did not affect that of young animals. Restraint stress induced hyperthermia in both aged and young rats. However, 90 min after the beginning of restraint, PS-treated old rats showed a normalization of core temperature. Furthermore, restraint-plus-cold stress induced gastric ulcers in both aged and young rats. The treatment with PS was followed by a decreased incidence of gastric lesions in aged, but not in young rats. The mechanism of PS protective action against stress-induced behavioral and autonomic changes is unknown, but it may involve the brain level as this drug exerts a noteworthy influence on behavior and autonomic functions.

Phosphatidylserine reverses the age-dependent decrease in cortical acetylcholine release: a microdialysis study

In vivo basal acetylcholine (ACh) and choline (Ch) output from the parietal cortex of 3- and 19-month-old freely moving rats was measured by microdialysis. A dialysis tubing was inserted transversally through the parietal cortex 24 h before the experiment. ACh and Ch concentrations were determined in the same perfusate samples by HPLC with electrochemical detection. In 19-month-old rats treated with Tris buffer, ACh and Ch outputs were 39 and 16% lower, respectively, than in 3-month-old rats. Phosphatidylserine (PtdSer) administration (15 mg/kg i.p. daily) for 8 days to 19-month-old rats markedly attenuated the decrease in ACh release. The same treatment did not affect ACh and Ch outputs in 3-month-old rats. ACh and Ch outputs in 19-month-old rats administered either phosphatidylcholine (PtdCho) or o-phospho-dl-serine (P-Ser) (15 mg/kg i.p. daily) for 8 days were as low as in 19-month-old rats receiving Tris buffer only. It is possible that chronic PtdSer treatment improve ACh release in aging rats by increasing the availability of Ch for ACh synthesis.

Phosphatidylserine vesicles increase Ca2+ uptake by rat brain synaptosomes

Phosphatidylserine (PS) vesicles incorporated into rat brain synaptosomes increased total Ca2+ uptake. Total Ca2+ uptake was resolved in three components: K+ depolarization-induced Ca2+ uptake, Na+/Ca2+ exchange, and passive Ca2+ entry, which were differently affected by PS depending on the amount of incorporated phospholipid. K+ depolarization-induced Ca2+ uptake was stimulated by 0.05-0.10 mumol PS/mg protein while 0.10-0.30 mumol PS/mg protein increased Na+/Ca2+ exchange activity and passive Ca2+ entry but not K+ depolarization-induced Ca2+ uptake. High amounts of incorporated PS also increased passive Rb+ uptake.

Decrease of acetylcholine release from cortical slices in aged rats: investigations into its reversal by phosphatidylserine

The release of total acetylcholine (ACh) and [3H]ACh was investigated in electrically stimulated cortical slices prepared from 4- and 18-month-old male Wistar rats. The slices were prelabeled with [3H]choline ([3H]Ch) and perfused with Krebs solution containing physostigmine. Total ACh was measured and the nature of the tritium efflux identified by HPLC. The total tritium content in the slices at the end of the incubation period was half as great in the old as in young rats. A linear relationship was found between stimulation frequencies (2, 5, and 10 Hz) and fractional [3H]ACh release in both young and old rats. In the latter the release was significantly smaller. At 10 Hz stimulation frequency the ratio between the two 2-min stimulation periods, S2/S1, was higher in the 18-month-old rats than in the young rats. Specific activity of the evoked ACh release was significantly smaller in S2 than in S1 in 4-month-old rats only. These findings indicate that the young synthetize ACh from endogenous unlabeled Ch more than older rats. In 18-month-old rats both the evoked total ACh and [3H]ACh release, expressed as picograms per minute, showed an approximately 50% decrease in both S1 and S2 stimulation periods, with no significant difference in specific activity. Phosphatidylserine (PtdSer) administration (15 mg/kg, i.p. daily) for 1 week to 18-month-old rats prevented the reduction in total evoked ACh release but not the reduction in evoked [3H]ACh release. The specific activity of ACh release was therefore significantly smaller than that of the young and untreated old rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Modulatory effects of phosphatidylserine on the binding of muscarinic cholinergic receptor ligands. Studies in vitro and in vivo

The modulation of the binding of muscarinic cholinergic receptor ligands by phosphatidylserine purified from bovine cerebral cortex (BC-PS) was examined in vitro and in vivo. The enrichment of bovine cerebral cortical synaptosomal membranes with BC-PS, using a fusion technique, produced a concentration-dependent decrease in the affinity (increase in Kd) of [3H]quinuclidinyl benzylate (3H-QNB) specific binding to muscarinic acetylcholine receptors (mAChR), without changes in their maximal number (Bmax). Similar results were observed when [3H]oxotremorine (3H-OXO) was used to label a high affinity subpopulation of mAChR. On the other hand, preincubation of BC-PS liposomes with synaptosomal membranes in a nonoptimum fusion condition (at pH 7.4) did not alter the binding properties of both radioligands. Fusion experiments using a pure phosphatidylserine preparation from spinal cord revealed a similar decrement in the affinity of 3H-QNB specific binding. Five day's intraperitoneal (i.p.) administration of 15 mg/kg of BC-PS liposomes in rats increased the maximal number of cerebral cortical binding sites for 3H-OXO. Scatchard analysis revealed no changes in the apparent dissociation constant. This modification is selective in relation to the neural structure studied. Thus, BC-PS treatment did not modify 3H-OXO binding in the hippocampal formation and cerebellum. In contrast, parallel experiments using the muscarinic antagonist 3H-QNB showed no alteration in the binding properties of mAChR. Five day's i.p. administration of 15 mg/kg/d of phosphatidylcholine from bovine cerebral cortex (BC-PC) liposomes produced quite similar results to those obtained with BC-PS. These results indicate that mAChR are under the modulatory action of phosphatidylserine (PS) and phosphatidylcholine (PC), and suggest that this endogenous phospholipids may play a regulatory role on the mAChR. The possible implications of these findings on the effects of PC or PS treatment in neurological disorders involving a decrease in central cholinergic functions are discussed.

Chronic administration of phosphatidylserine during ontogeny enhances subject-environment interactions and radial maze performance in C57BL/6 mice

A longitudinal behavioral study was performed in mice exposed to the bovine brain phospholipid phosphatidylserine (BC-PS) from birth until sixty days. Examination of treated and control pups revealed no effect of the treatment on body weight nor on sensorimotor reflexes. At one and two months of age, when placed in an open field and, particularly, in the presence of a novel object, treated mice were found more interactive with their environment than control mice. Finally, when submitted to a radial eight-arm maze problem, choice accuracy was higher and maze-running strategies more adaptive in treated than in control adult mice. These results suggest a stimulating effect of the treatment on subject-environment interactions during ontogeny underlying improved cognitive abilities in adulthood.

Phosphatidylserine administration during postnatal development improves memory in adult mice

Postnatal administration of an aqueous suspension of phosphatidylserine (BC-PS) to C57BL/6 mice resulted in improvement of memory processes in adulthood, as assessed in a passive avoidance task. These findings are discussed in terms of the effects of BC-PS on cholinergic mechanisms and of cholinergic patterns of this inbred strain.

In vivo action of phosphatidylserine, amitriptyline and stress on the binding of [3H]imipramine to membranes of the rat cerebral cortex

Liposomes of bovine brain phosphatidylserine and of phosphatidylcholine were prepared and injected i.p. into rats for 5 days. Another group received i.p. injections of amitriptyline in addition to phosphatidylserine. Subgroups of control and phosphatidylserine-injected rats were submitted to an acute swimming stress for 15 min. The number of [3H]imipramine binding sites in the phosphatidylserine-injected rats, decreased 23% whereas there was no change in the phosphatidylcholine-injected rats. The combination of amitriptyline and phosphatidylserine produced a more marked reduction in [3H]imipramine binding (-47%). Control rats undergoing acute stress showed a 30% decrease in [3H]imipramine binding whereas the stress did not significantly change the control values of the phosphatidylserine-treated animals. These findings are discussed in relation to the known action of phosphatidylserine on several neurotransmitter systems and on the potentiation of antidepressant effects.

Nootropic drugs and brain cholinergic mechanisms

1. This review has two aims: first, to marshal and discuss evidences demonstrating an interaction between nootropic drugs and brain cholinergic mechanisms; second, to define the relationship between the effects on cholinergic mechanisms and the cognitive process. 2. Direct or indirect evidences indicating an activation of cholinergic mechanisms exist for pyrrolidinone derivatives including piracetam, oxiracetam, aniracetam, pyroglutamic acid, tenilsetam and pramiracetam and for miscellaneous chemical structures such as vinpocetine, naloxone, ebiratide and phosphatidylserine. All these drugs prevent or revert scopolamine-induced disruption of several learning and memory paradigms in animal and man. 3. Some of the pyrrolidinone derivatives also prevent amnesia associated with inhibition of acetylcholine synthesis brought about by hemicholinium. Oxiracetam prevents the decrease in brain acetylcholine and amnesia caused by electroconvulsive shock. Oxiracetam, aniracetam and pyroglutamic acid prevent brain acetylcholine decrease and amnesia induced by scopolamine. Comparable bell-shaped dose-effect relationships result for both actions. Phosphatidylserine restores acetylcholine synthesis and conditioned responses in aging rats. 4. The mechanisms through which the action on cholinergic systems might take place, including stimulation of the high affinity choline uptake, are discussed. The information available are not yet sufficient to define at which steps of the cognitive process the action on cholinergic system plays a role and which are the influences of the changes in cholinergic function on other neurochemical mechanisms of learning and memory.

Microinfusion of clonidine and yohimbine into locus coeruleus alters EEG power spectrum: effects of aging and reversal by phosphatidylserine

1. The behavioural and electrocortical (ECoG) power spectrum effects of clonidine, and yohimbine, an agonist and an antagonist at alpha 2-adrenoceptors, after their unilateral microinfusion into the rat locus coeruleus (LC) in young (50-70 days old) and old (13-15 months old) rats were studied. 2. Clonidine (0.09, 0.19, 0.28 and 0.56 nmol) microinfused into the LC of young rats induced dose-dependent behavioural and ECoG slow wave sleep (SWS) with a significant increase in total voltage power and power in the lower frequency bands. In contrast, yohimbine (1.3 and 2.6 nmol) infused into the LC of young rats produced ECoG desynchronization and a significant decrease in total voltage power. 3. In contrast to young rats, clonidine (0.19 and 0.28 nmol) given into the LC did not affect behaviour and the ECoG power spectrum in old rats. However, after higher doses of clonidine (0.56 and 1.2 nmol) a small and short-lasting period of behavioural and ECoG SWS was still evident. Similarly, in old rats yohimbine, at a dose (1.3 nmol) which was stimulative in young animals, did not significantly affect behaviour and ECoG power spectrum. Higher doses of yohimbine (2.6 and 5.2 nmol) were required to induce behavioural and ECoG changes similar to those observed with lower doses of yohimbine in young rats. 4. Chronic treatment with phosphatidylserine (30 mg kg-1, orally, daily for 21 and 30 days), was able gradually to restore in old rats, in comparison with a vehicle-treated group, the responsiveness of alpha 2-adrenoceptors to clonidine and yohimbine given into the LC.

Phosphatidylserine activity on prolactin brain receptors of aged rabbits

1. PRL receptors in the hypothalamus and substantia nigra of aged rabbits (28-month-old) are significantly reduced in comparison with young rabbits (6-month-old). 2. Repeated treatments with BC-PS are able to gradually increase the PRL receptor number both in hypothalamus and nigra. However only after 30 days of treatment the binding reaches the mean values observed in young rabbits. 3. Aged rabbits showed an evident increase in PRL plasma levels in comparison with young animals. In BC-PS treated animals this increase was not more apparent. Moreover in young rabbits treated with BC-PS an evident decrease in basal PRL plasma levels was observed.

Dendritic spine loss in hippocampus of aged rats. Effect of brain phosphatidylserine administration

Dendritic spine density of pyramidal cells in region CA1 of the hippocampus has been evaluated in young (3 months), old (27 months) and old phosphatidylserine (BC-PS)-treated rats. BC-PS (50 mg/kg, suspended in tap water) was administered daily, starting at the age of 3 months until 27 months. Spine density was analyzed on Golgi-stained pyramidal neurons by a computerized analysis system. In 27-month-old rats, spine density showed with respect to 3-month-old animals, a significant decrease in both basal and apical dendrites (p less than 0.01; one-way ANOVA), with a mean loss of 12.11% in the basal dendrites and of 10.64% in the apical ones. In 27-month-old rats treated with BC-PS, values of spine density were not statistically different when compared to those of 3-month-old animals. The mechanisms underlying the beneficial effect of BC-PS treatment on neuronal connectivity might be explained on the basis of its pharmacological actions on neuronal membranes [9], neurotransmission [43] and/or interaction with NGF [7].

Effect of phosphatidylserine on acetylcholine release and content in cortical slices from aging rats

Cortical slices were prepared from male rats 3 to 28 months old. The slices were superfused with choline-enriched Krebs solution containing physostigmine and electrically stimulated at frequencies of 1, 2 and 5 Hz for 5 min periods preceded and followed by rest periods. The amount of acetylcholine released during the stimulation periods was quantified by bioassay. In some experiments acetylcholine content was measured at the end of the superfusion period in stimulated and unstimulated slices. The evoked acetylcholine release was constant between 3 and 11 months of age at each frequency tested and showed a 50% decrease between 11 and 14 months of age with no further decrease up to 28 months. No difference in the evoked acetylcholine release was detected between 3 and 16 month old rats if the old rats were pretreated with phosphatidylserine 15 mg/kg IP for at least 7 days. The effect of phosphatidylserine lasted for 5 days after interruption of the treatment. There was no difference in acetylcholine content between the stimulated and unstimulated slices in 3 month old rats. In 16 month old rats stimulation brought about a 44% decrease in acetylcholine content. This decrease did not occur in rats pretreated with phosphatidylserine for 7 days. Phosphatidylserine appears to restore acetylcholine release in aging rats by maintaining an adequate acetylcholine supply in the slices.

Phosphatidylserine vesicles increase rat brain synaptosomal adenylate cyclase activity

Phosphatidylserine vesicles incubated in hypotonic conditions with rat brain synaptosomes increased basal adenylate cyclase activity but did not modify the response of the enzyme to norepinephrine. Moreover, phosphatidylserine antagonized the stimulation of adenylate cyclase activity by NaF. We suggest that in present experimental conditions the effect of phosphatidylserine vesicles is at the level of the GS regulatory protein of adenylate cyclase.

Modulation of [3H]flunitrazepam binding to rat cerebellar benzodiazepine receptors by phosphatidylserine

The influence of phosphatidylserine on ligand binding to the benzodiazepine/GABA receptor complex was assessed in rat cerebellar synaptic membranes and in a detergent-solubilized membrane preparation. Intact synaptic membranes or membranes solubilized with the zwitterionic detergent CHAPS (3-[(3-cholamidopropyl)-dimethylammonio]propanesulfonate) were incubated with a range of concentrations of phosphatidylserine for 2 h at 4 degrees C, prior to use in radioligand binding assays. Phosphatidylserine, an endogenous membrane phospholipid, facilitated the site-specific binding of [3H]flunitrazepam to synaptic membranes and CHAPS-solubilized preparations. In addition, phosphatidylserine inhibited the facilitation of [3H]flunitrazepam binding induced by either cartazolate or gamma-aminobutyric acid (GABA). Although the maximum effect (38% facilitation of [3H]flunitrazepam binding; greater than 90% inhibition of the cartazolate action) was produced using 130 microM phosphatidylserine, a significant enhancement of [3H]flunitrazepam binding could be observed upon preincubation of synaptic membranes with concentrations of phosphatidylserine as low as 5 microM. These results suggest that endogenous phosphatidylserine may play a role in the regulation of benzodiazepine/GABA receptor function, possibly through modulation of the mechanisms which functionally link the various components of this complex receptor system.

Age-dependent spontaneous EEG bursts in rats: effects of brain phosphatidylserine

During aging, male Sprague-Dawley rats display increasing frequency of bursts of seizure-like EEG patterns. They also have a decreased retention of passive avoidance response and a loss of spontaneous alternation in a Y maze. A study was made on the effects of chronic administration of phosphatidylserine in aged rats. It was found that BC-PS reduced by 65% the number of seizures, and by 70% their duration. It also facilitated retention of passive avoidance and of spontaneous alteration behavior. These results suggest that phosphatidylserine can affect electrophysiological and behavioral parameters in aged rats probably by counteracting age-related biochemical changes.

Phosphatidylserine increases acetylcholine release from cortical slices in aged rats

Acetylcholine release was investigated in cortical slices superfused with choline-enriched Krebs solution containing physostigmine. Slices were prepared from 3 and 24 month old rats treated with either Tris buffer or sonicated suspensions of phosphatidylserine and phosphatidylcholine in Tris buffer. Slices were electrically stimulated at frequencies of 1, 2 and 5 Hz for 5 min periods preceded and followed by rest periods. ACh content of the superfusate was quantified by bioassay. In the 24 month old rats treated with Tris buffer, acetylcholine release, at all frequencies tested, was approximately 50% lower than that in the 3 month old rats. On the contrary, no significant decrease in ACh release was found in the 24 month old rats treated for 30 days with phosphatidylserine (15 mg/kg IP). The same treatment did not increase acetylcholine release in 3 month old rats. Acetylcholine release in 24 month old rats receiving a single administration of phosphatidylserine (15 mg/kg IP) or phosphatidylcholine (15 mg/kg IP) for 30 days was as low as in the 24 month old rats receiving the Tris buffer only. It is proposed that the chronic phosphatidylserine treatment may reduce the age-induced decrease in acetylcholine release by acting on the stimulus-secretion coupling mechanism.

Behavioral effects of phosphatidylserine in the aged Fischer 344 rat: amelioration of passive avoidance deficits without changes in psychomotor task performance

A series of studies was conducted to evaluate the effects of phosphatidylserine (PS) in aged Fischer 344 rats. No effects were observed in any of four psychomotor tasks in which aged rats normally show deficits, nor on measures of shock sensitivity. However, significant dose-related effects on retention of passive avoidance were observed when PS was given both 30 min prior to training and retention. Further, in a second experiment similar positive effects were observed when PS was given only 30 min prior to training, as well as only 5 min following training. These results suggest that one effect of PS may include an ability to enhance neural events involved in the encoding or consolidation of new information into memory.

Ethanol and membrane lipids

Although ethanol is known to exert its primary mode of action on the central nervous system, the exact molecular interaction underlying the behavioral and physiological manifestations of alcohol intoxication has not been elucidated. Chronic ethanol administration results in changes in organ functions. These changes are reflective of the adaptive mechanisms in response to the acute effects of ethanol. Biophysical studies have shown that ethanol in vitro disorders the membrane and perturbs the fine structural arrangement of the membrane lipids. In the chronic state, these membranes develop resistance to the disordering effects. Tolerance development is also accompanied by biochemical changes. Although ethanol-induced changes in membrane lipids have been implicated in both biophysical and biochemical studies, measurements of membrane lipids, such as cholesterol content, fatty acid unsaturation, phospholipid distribution, and ganglioside profiles, have not produced conclusive evidence that any of these parameters are directly involved in the action of ethanol. On the other hand, there is increasing evidence indicating that although ethanol in vitro produces a membrane-fluidizing effect, the chronic response to this effect is not to change the membrane bulk lipid composition. Instead, changes in membrane lipids may pertain to small metabolically active pools located in certain subcellular fractions. Most likely, these lipids are involved in important membrane functions. For example, the increase in PS in brain plasma membranes may provide an explanation for the adaptive increase in synaptic membrane ion transport activity, especially (Na,K)-ATPase. There is also evidence that the lipid pool involved in the deacylation-reacylation mechanism (i.e., PI and PC with 20:4 groups) is altered after ethanol administration. An increase in metabolic turnover of these phospholipid pools may have important implications for the membrane functional changes. Obviously, there are other lipid-metabolizing enzyme systems that may exert similar effects but have not yet been investigated in detail. From the results of these studies, it is concluded that the multiple actions of ethanol are associated with changes in enzymic systems important in the functional expression of the membranes.

Lipids of nervous tissue: composition and metabolism

As indicated in the Introduction, the many significant developments in the recent past in our knowledge of the lipids of the nervous system have been collated in this article. That there is a sustained interest in this field is evident from the rather long bibliography which is itself selective. Obviously, it is not possible to summarize a review in which the chemistry, distribution and metabolism of a great variety of lipids have been discussed. However, from the progress of research, some general conclusions may be drawn. The period of discovery of new lipids in the nervous system appears to be over. All the major lipid components have been discovered and a great deal is now known about their structure and metabolism. Analytical data on the lipid composition of the CNS are available for a number of species and such data on the major areas of the brain are also at hand but information on the various subregions is meagre. Such investigations may yet provide clues to the role of lipids in brain function. Compared to CNS, information on PNS is less adequate. Further research on PNS would be worthwhile as it is amenable for experimental manipulation and complex mechanisms such as myelination can be investigated in this tissue. There are reports correlating lipid constituents with the increased complexity in the organization of the nervous system during evolution. This line of investigation may prove useful. The basic aim of research on the lipids of the nervous tissue is to unravel their functional significance. Most of the hydrophobic moieties of the nervous tissue lipids are comprised of very long chain, highly unsaturated and in some cases hydroxylated residues, and recent studies have shown that each lipid class contains characteristic molecular species. Their contribution to the properties of neural membranes such as excitability remains to be elucidated. Similarly, a large proportion of the phospholipid molecules in the myelin membrane are ethanolamine plasmalogens and their importance in this membrane is not known. It is firmly established that phosphatidylinositol and possibly polyphosphoinositides are involved with events at the synapse during impulse propagation, but their precise role in molecular terms is not clear. Gangliosides, with their structural complexity and amphipathic nature, have been implicated in a number of biological events which include cellular recognition and acting as adjuncts at receptor sites. More recently, growth promoting and neuritogenic functions have been ascribed to gangliosides. These interesting properties of gangliosides wIll undoubtedly attract greater attention in the future.(ABSTRACT TRUNCATED AT 400 WORDS)