Cognitive and physiological effects of Omega-3 polyunsaturated fatty acid supplementation in healthy subjects.

BACKGROUND: It has been reported that Omega-3 fatty acids may play a role in nervous system activity and that they improve cognitive development and reference memory-related learning, increase neuroplasticity of nerve membranes, contribute to synaptogenesis and are involved in synaptic transmission. The aim of this study was to examine the effects of Omega-3 supplementation on some cognitive and physiological parameters in healthy subjects. MATERIALS AND METHODS: Subjects were tested at the beginning of the experiment and after 35 days. In this period they were supplemented with Omega-3 polyunsaturated fatty acids. A group was supplemented with olive oil (placebo). Tests involving different types of attention were used, i.e. Alert, Go/No-Go, Choice and Sustained Attention. For each test, the reaction time, the event-related potentials by electroencephalogram (EEG) and the electromyography (EMG) of the forefinger flexor muscle were recorded. The Profile of Mood States test (POMS) was also administered. RESULTS: Blood analyses showed that after Omega-3 supplementation the arachidonic acid/eicosapentaenoic acid ratio (AA/EPA) was strongly reduced. The mood profile was improved after Omega-3 with increased vigour and reduced anger, anxiety and depression states. This was associated with an effect on reactivity with a reduction of reaction time in the Go/No-Go and Sustained Attention tests. The latency of EMG activation was concomitantly reduced in the same tests plus Choice. An EEG frequency shift towards the theta and alpha band were recorded in all the tests after Omega-3. CONCLUSIONS: Omega-3 supplementation is associated with an improvement of attentional and physiological functions, particularly those involving complex cortical processing. These findings are discussed in terms of the influence of Omega-3 on the central nervous system.

Blood profiles, body fat and mood state in healthy subjects on different diets supplemented with Omega-3 polyunsaturated fatty acids.

BACKGROUND: Diets and Omega-3 polyunsaturated fatty acids have been considered as important factors to reduce the risk of cardiovascular and inflammatory diseases, but there are few details on the effects on healthy subjects. The aim of the present study was to examine the variation of several physiological parameters in healthy subjects on different diets supplemented with Omega-3 fatty acids. MATERIALS AND METHODS: The experiment was carried out on 33 subjects divided into four groups according to a double-blind cross-over design with a 1 : 1 ratio for Omega-3 (vs. placebo) and open-label parallel-groups with a 1 : 1 ratio for the Zone diet (vs. the diet suggested by the Italian National Research Institute for Nutrition and Foods). Blood samples were collected at the beginning of the experiment and after 35 (cross-over) and 70 days. The Profile of Mood States test (POMS) was also performed. RESULTS: The arachidonic acid/eicosapentaenoic acid ratio (AA/EPA) was strongly reduced by Omega-3 with a supplementary effect of the diet and in particular the Zone diet. The AA/EPA reduction was correlated with a concomitant decrease of insulin and homocysteine levels. The Zone diet reduced skinfold thickness and body fat percentage and also showed antioxidant effects. The mood state changed after Omega-3 supplementation, with an increased POMS index. This was related to a concomitant reduction of AA/EPA and was particularly evident in the Zone diet. CONCLUSION: AA/EPA and mood state are differently influenced by diet and Omega-3, body fat is particularly reduced by Zone diet, while blood parameters such as triglycerides/HDL ratio, insulin and homocysteine are related to AA/EPA variations. These findings are discussed in terms of differences in the composition of the diets and the influences of Omega-3 on physiological functions.

Heart rate variability in subjects with different hypnotic susceptibility receiving nociceptive stimulation and suggestions of analgesia.

The aim of the present study was to investigate the possible hypnotizability-related modulation of heart activity during nociceptive stimulation (pressor pain) and during nociceptive stimulation associated with the suggestion of analgesia in not hypnotized healthy individuals with a high (Highs) and a low (Lows) hypnotic susceptibility. ECG and respirogram were recorded. Standard time and frequency domain indexes were evaluated, together with the sd1 and sd2 values of the Poincaré plot over the RR series. Results showed self reports of analgesia in Highs and a significant increase of the respiratory frequency during stimulation in both groups. Very few significant differences between groups and among conditions were detected for mean RR and heart rate variability (HRV) through spectral analysis. and through the Poincaré indexes evaluation. On the contrary, a promising approach seems to be the study of the correlations among standard and Poincaré variables. In particular, different changes in (or even lost of) correlations were enlightened in Highs and Lows, suggesting a different modulation of RR in the two groups, probably due to the very low frequency components of HRV. Different roles of sympathetic and parasympathetic activities during stimulation can be suggested.

Policosanol, reaction time and event-related potentials.

The aim of the present study was to compare the results of a 1-week, double-blind placebo-controlled trial investigating the effects of isopolicosanol and octacosanol on reactivity and related brain activity. In particular, reaction time (RT) and event-related potentials such as contingent negative variations (CNV) and P300 (P3) have been studied. Thirty sedentary healthy students were tested before and after treatment (3.6 mg/die for 7 days) with orally administered tablets of placebo (group A), isopolicosanol (B) and octacosanol (C). RT were studied according to three procedures: simple RT (SRT), go/no-go RT (GRT) and choice RT (CRT). Results show that before treatment, there were no significant differences between groups A, B and C. After treatment, the RT of group A was unchanged, while the RT of groups B and C were reduced. In group B, in the SRT test, the reduction of RT was accompanied by electrical data exhibiting increased amplitudes of CNV and shorter latencies of P3. These results show that the main effect on reactivity and event-related potentials can be ascribed to policosanol and is mainly evident in the SRT test.

Reactivity and event-related potentials during attentional tests in athletes.

A series of attentional tests involving reaction times (RTs) was administered to 12 high-level young (age 17-18 years) volleyball players. During the tests, event-related potentials were recorded by electroencephalogram. In a simple reaction-time test (SRT), the subjects had to respond to a letter that appeared on a white screen. Other tests (attentional shifting tests) consisted of a go/no-go reaction time and a choice reaction time (CRT), divided into a short-latency CRT and a long-latency CRT. In the pre-stimulus period of these tests, there is a shift from broad attention to selective attention, represented by a crowding of black points on the computer screen, followed by the appearance of a letter in the centre of the crowding. The results show that RT increased from SRT to CRT. In the attentional shifting tests, averaged waves of event-related potentials showed a contingent-negative-variation-like wave that was closely related to selective attention (selective attention wave, SAW) before the onset of the stimulus. After the stimulus, a P3 complex was recorded. Correlations were found between the SAW amplitude and P3 latency and amplitude, and between these parameters and RT and its variability. Higher SAW and P3 amplitudes were accompanied by a shorter RT and a lower variability. The characteristics and the correlations that exist between the various parameters are consistent with a possible use of these tests in the analysis of the attentional styles of athletes, and in the evaluation of their progress with training.

Emotional behavior in female rabbits: hippocampal EEG and neuroendocrine aspects.

Behavior, hippocampal electrical activity, plasma hormones and hippocampal choline acetyltransferase (ChAT) were considered in two groups of female rabbits, different in age and condition of breeding, both in the presence and absence of emotional stimuli. In the two groups of female rabbits (4 and 18 months old), permanent electrodes were implanted bilaterally in the two dorsal hippocampi and, one week later, the animals were exposed for three consecutive days to the following tests: Day 1, novel environment (NE); Day 2, object with odor (O); Day 3, sparrow hawk (SP). Behavior: in comparison with Day 1, exploration was decreased by the object and by the sparrow hawk in the older females and increased in the younger ones. Quiet and alert immobility was higher during the SP test, while freezing and pointing were lower in the older females than in the young ones. Electrical activity: peak frequency was lower in younger females than in the older ones. The frequency band distribution corresponding to exploration and immobility showed that in the older females the % of high frequency band increased from the first to the third day of testing, while an opposite trend was present in the younger females. In the case of freezing the hippocampal electric activity showed a more rhythmical component in younger females than in the older ones. Hormones: increased corticosterone levels after the SP test were directly correlated with exploration and inversely correlated with freezing. Dorsal hippocampal ChAT was directly correlated with quiet immobility. These data indicate a relationship between the responses to the anxious/fearful stimuli and the age and/or breeding experience of the female rabbits; this is shown by both the hippocampal electrical activity and the behavioral differences between the two groups.

Hippocampal electrical activity and behavior in the rabbit.

Different approaches to the study of the relationship between hippocampal electrical activity and behavior have shown that hippocampal EEG varies according to different behavioral aspects. In particular, a rhythmic slow activity (RSA, Theta rhythm) can be recorded during voluntary movements and to a lesser degree during immobility. In laboratory experiments, we tried to evaluate the influence on the hippocampal EEG of external stimuli evoking emotional or cognitive responses. Similar electrical responses were observed during animal hypnosis and in the presence of threatening stimuli, while some electrical parameters, such as frequency and rhythmicity, varied according to the nature of the stimulus. In order to have greater and clearer information, we adopted a neuro-ethological approach ch. which allowed us to classify behavior into several categories and to record the hippocampal EEG during natural behavior. The influence exerted on hippocampal electrical activity by novel stimuli and the electrical profiles recorded during exploratory behavior or alert or quiet immobility allowed us to classify the hippocampal EEG on the basis of frequency and rhythmicity. Moreover, the study of social behavior showed that the variations of the electrical parameters of the hippocampal activity depended on the characteristics of the stimulus and that typical electrical profiles could be observed in immobile or motor activities caused by specific stimuli. Socially dominant and subordinate rabbits could also be distinguished on the basis of hippocampal electrical parameters.

Hippocampal electrical activity in rabbits during exploration of a semi-natural environment.

The hippocampal EEG shows characteristic profiles during different behavioural items. A class of hippocampal neurones is active when the animal is in specific places of an environment (place units). However, there are only a few neurones and the role of the hippocampal EEG in spatial information processing remains to be explained. In the present experiment we studied the exploratory behaviour of rabbits (implanted with chronic electrodes in the hippocampus) in an open-air, semi-natural environment. Hippocampal EEG was recorded by telemetry and related to exploratory behaviour by superimposition onto video. Six rabbits were introduced singly to the semi-natural environment and each remained there for 3 days. Their behaviour and EEG was analysed for three 30 min sessions (at 0, 6 and 56 h). Exploration was the main behaviour in the first observation and decreased progressively in the following sessions. The environment was divided into three zones which were explored differently through time. The hippocampal EEG, recorded during exploration, presented an increase of frequency from the first to the second observation. However, since EEG frequency increased when the animal explored the central area of the enclosure, a response in the place domain cannot be excluded.

Response of cat cortical neurons to position and movement of the femur.

The contribution of joint afferents to the response of cortical neurons in area 3a to mechanical stimulation of the contralateral hindlimb was evaluated in cats anesthetized with sodium pentobarbital and paralyzed with pancuronium bromide. The hindlimb projection to the pericruciate cortex was established by recording the evoked potentials to electrical stimulation of the sciatic nerve and some of its branches, the bicepssemitendinosus and the quadratus femoris. Out of 169 neurons, 63 responded exclusively to cutaneous stimuli (superficial), whereas the others could be activated by local pressure of hindlimb muscles and/or by joint rotation (deep). Deep neurons were classified as slowly adapting (SA) or rapidly adapting (RA) units. In the neurons responding exclusively to joint rotation, the site of the receptive field could not be identified with certainty. In 13 deep neurons, their firing was affected by rotation of multiple joints of the contralateral hindlimb. In an attempt to identify the source of activation of cortical neurons, partial denervations and muscle disconnections were performed in five animals to isolate and stimulate the hip capsule. In these preparations, in 14 of 15 cortical neurons the source of activation was localized in the periarticular muscles, with no response to mechanical stimulation of the joint capsule. Only one neuron (SA) could be selectively excited by punctate pressure on the hip capsule. Our results suggest that in neurons of area 3a of the cat, the information about the position of the femur relies mainly on muscle afferents.

Hippocampal cholineacetyltransferase activity, agonistic behaviour and social stress in male rabbits.

Agonistic behaviour was observed in pairs of unfamiliar male rabbits living in an outdoor enclosure. Attack, Chase, Follow and Cross-over were scored. On the basis of their frequencies the subjects in the pair were assigned a first or second rank-position. Hippocampal cholineacetyltransferase (ChAT) and plasma levels of corticosterone were considered in relation to rank. ChAT levels in the dorsal hippocampus varied in relation to agonistic behaviour. Second-ranking subjects had significantly higher levels of ChAT than the first-ranking animals and had levels of corticosterone which were markedly higher at the end of the experimental period than at the beginning. A negative correlation was found between Attack and ChAT levels in the dorsal hippocampus. These results suggest the presence of social stress in the second-ranking animals and indicate a state of activation of the hippocampus in relation to agonistic behaviour.

Immune and endocrine aspects of social and territorial behavior in male rabbits.

Although there have been some studies of the relation between behavior and mitogen-induced lymphocyte proliferation and immunoglobulin synthesis, few data are available about the effect of behavior on specific lymphokine production. In this study, we describe the effect of social and territorial behaviors on interferon-gamma (IFN-gamma) production by concanavalin A-stimulated peripheral blood mononuclear cells (PBMCs) in pairs of socially naive male rabbits living in a seminatural open-air environment. We also assayed PBMC glucocorticoid receptors (GcRs) and plasma corticosterone (C). Three groups of behaviors were identified: agonistic (Mount and Follow), affiliative (Groom) and territorial (Mark and Dig). Mount was correlated with Follow, while Mark was correlated with Dig. Groom was correlated with all the other behaviors. Groom, Mark, Mount and Follow were all positively correlated with PBMC GcRs. Groom and PBMC GcRs were each negatively correlated with plasma C. The two rabbits in each pair could be distinguished in terms of territorial behavior, since one animal always had a higher score. The animals with the higher level of territorial behavior within the pairs exhibited a significant increase in IFN-gamma production at the end of the experimental period. They also showed a positive correlation between the percentage variations of IFN-gamma production and PBMC GcRs. It is suggested that social factors, especially territorial behavior, affect adrenocortical activity and IFN-gamma production.

Effect of deltorphin on behavior and hippocampal electrical activity in rabbits.

To clarify the role of delta-opioid receptors on modulation of hippocampal electrical activity and behavior, deltorphin (DT), a naturally occurring heptapeptide that selectively binds to delta-opioid receptors, was intravenously (IV) administered to rabbits. For this purpose, at 8-day intervals, the effects of IV administration of normal saline and IV infusion of synthetic DT (1 mg/kg b.wt. for 2 min) on the spontaneous behavior in neutral environment, both in absence of any external stimulus and after the introduction of a stuffed predator, were examined in seven adult male rabbits, on separate and successive occasions. During each session of experimental procedure, hippocampal EEG was also recorded by telemetry. Behavioral activity showed an increase in alert and reactive immobility after the peptide injection in comparison with that observed during control period (saline administration). Under DT treatment the frequency of hippocampal electrical activity decreased, and a reduction in rhythmicity of electrical pattern was also observed in presence of stressful stimulus. These findings show that DT may affect neural and behavioral elements related to the control of attentional and emotional processes, suggesting a modulating role of delta-opioid receptors.

Effect of dermorphin on behavior and hippocampal electrical activity in rabbits.

Dermorphin, a naturally occurring heptapeptide that selectively binds to mu-opioid receptors, was injected intravenously 0.4 mg/kg in male rabbits. Eight days before injection the spontaneous behavior of the animals was observed in a neutral environment in the absence of external stimuli. At the same time, hippocampal EEG was recorded by telemetry. After dermorphin injection, the same experimental procedure was repeated. Behavior showed a strong increase in quiet immobility and a concomitant reduction in voluntary activities as compared to control periods. Treatment did not affect either the pattern or the frequency of hippocampal electrical activity.

Self-directed behaviour and hippocampal electrical activity in rabbits living in a semi-natural environment.

Rabbits living in a semi-natural environment show a variety of behavioural elements related to voluntary or automatic movements. The aim of the present experiment was to study the hippocampal electrical correlates of self-directed activities occurring during spontaneous behaviour and emotional responses (the presence of a second rabbit of the same sex: intruder). Behaviour was divided into two broad categories. One included autocleaning elements such as scratching, shaking, washing and self-grooming. The other was characterized by consummatory activities: eating and drinking. Hippocampal activity was recorded by telemetry and the EEG periods related to specific behavioural elements were selected and analyzed. The electrical parameters were different for the various behavioural elements, for example rhythmic and irregular EEG patterns were recorded in different percentages during autocleaning and consummatory activities. Differences were also observed in the frequency peak distributions of power spectra. Confrontations influenced the occurrence of self directed behavioural elements and modified the pattern and frequency of hippocampal EEG during autocleaning activities. Results show that environmental variations can affect automatic behaviours and influence the mechanisms of hippocampal function.

Hippocampal electrical activity during social interactions in rabbits living in a seminatural environment.

The aim of the present experiment was to study the effect on the electrical activity of the hippocampus of interactions between male rabbits. The behavioral and electrical correlates of social interactions were studied in 13 animals living in a seminatural environment. Rabbits carrying chronic microelectrodes implanted in the hippocampus were introduced singly into a large, natural open air enclosure and their spontaneous behavior observed until they had adapted to the environment. Hippocampal EEG was recorded by telemetry. Subsequently, a second rabbit (intruder) was introduced into the enclosure. Hippocampal EEG and the concomitant behavior of the resident were stored and analyzed. Alerting reactions, approaching and conflictual elements were characterized by typical electrical patterns and parameters. Power spectra of hippocampal EEG showed a significant increase in frequency passing progressively from environment-related behaviors to more specific elements directed towards the intruder. Behavioral elements belonging to the same modality, such as running, chase and flight had different hippocampal EEG frequency distributions. Seven residents showed a clear prevalence of offensive reactions (offensive rabbits) and six defensive elements (defensive rabbits). Defensive animals showed very high frequency levels during nose and flight. Exploration of offensive rabbits in the period preceding and following the introduction of the intruder was characterized by higher EEG frequency values than exploration of defensive animals.

Hippocampal electrical activity and behavior in rabbits living in a seminatural environment: reactions in the presence of a dog.

The aim of the present experiment was to correlate behavioral and electrical events recorded in the presence of a threatening stimulus, namely a dog presented to rabbits living in a seminatural environment. Behavioral and concomitant EEG, recorded by telemetry, were studied in rabbits carrying chronic electrodes implanted in the hippocampus, before, during, and after the introduction of a dog into the environment around the enclosure. The threatening stimulus caused a variety of emotional responses in the rabbits, associated with high rhythmicity and high frequency levels in the hippocampal EEG. After removal of the dog the state of alarm of the animals persisted with long periods of alert immobility characterized by a further increase in hippocampal EEG frequency. Data show that emotional and environmental aspects can affect the hippocampal electrical activity recorded during specific behavioral elements.

Immobility reactions in socially behaving rabbits: Relation to hippocampal electrical activity.

The presence of an intruder conspecific of the same sex caused a series of conflict reactions in rabbits living in a semi-natural environment. In some animals, defensive responses were predominant and two immobility reactions were observed. One consisted of freezing when the intruder was exploring at a distance; the other consisted of subdued posture in close contact with the intruder. Hippocampal EEG, recorded by telemetry, showed two different profiles. During freezing, rhythmic slow activity prevailed and during subdued posture an irregular pattern was predominant. Frequency increased when the intruder was in close contact with the resident. Aspects such as distance or behaviour of the intruder were found to affect both behavioural strategies and hippocampal electrical responses.

Different effects of ACTH fragments on hippocampal EEG and behavior.

The hippocampal electrical activity and behavior of rabbits have been studied in the presence of novel and emotional stimuli. The effects of these stimuli have been recorded in controls and in groups of animals treated with ACTH (4-10)(10 micrograms/100 g, i.m.) and ACTH (1-24) (10 micrograms/100 g, i.m.). Recordings were made immediately and 30 min after injection. ACTH (4-10) injection failed to evoke any significant behavioral or electrical response. Rabbits recorded 30 min after ACTH (1-24) injection showed a reduction of hippocampal RSA (rhythmic slow activity) frequency and behavioral activity. In particular, reduction of exploration, self-grooming, motor activity and approaches to the new object have been observed. Since ACTH is characterized by a corticotropic action these results can be due to corticosteroid stimulation.

Cholinergic and glutaminergic control of hippocampal RSA during behavior in rabbits.

An experimental model, with novel environmental stimuli, has been used in order to study the effects of cholinergic and glutaminergic modulation on hippocampal electrical activity and behavior. The test consisted in the introduction of a rabbit in an experimental cage in the absence of external stimuli (neutral environment) followed by the introduction into the cage of a novel object containing odorous vegetable branches, a stuffed sparrow-hawk and a live cat. The effects of drug treatments on hippocampal rhythmic slow activity (RSA) parameters (total amount, episode durations and frequency) were studied. Physostigmine (0.1 mg/kg) increased RSA amount both during immobility and movements and was effective only on the frequency of the immobility related RSA. Scopolamine (0.4 mg/kg) reduced the percentage of RSA occurring during immobility and movements and the frequency of the movement related RSA. Glutamic acid diethyl ester (GDEE) (400 micrograms), injected into the dorsal hippocampus, had qualitative effects similar to those obtained with scopolamine, but, quantitatively, they were less pronounced. The combination between GDEE and scopolamine potentiated the effects of the two drugs. Results support the assumption that cholinergic septal input is responsible for hippocampal RSA and the glutaminergic entorhinal input to the hippocampus modulates RSA, probably under cholinergic control.

Hippocampal electrical activity and behavior in the presence of novel environmental stimuli in rabbits.

Male rabbits have been used in a simultaneous study of their behavioral and neural activity in different experimental situations related to attention and emotionality. The electrical activity of the dorsal hippocampus and frontal cortex was recorded in the following experimental situations: Neutral Environment (response to a novel environment); Object (response to a novel stimulus); Stuffed sparrow hawk; and live cat. Results show that behavioral and electrical responses depend upon: (a) the nature of the stimulus; and (b) whether or not the stimulus is moving. As for the immobile stimuli, the stuffed animal presentation significantly reduced both behavioral activity and percentage and frequency of rhythmic slow activity (RSA); prolonged periods of ECoG synchronization were also recorded. The introduction of the live cat greatly increased the percentage and frequency of RSA, especially when the cat was looking at the rabbit. The experimental situations caused differences in the distribution of RSA frequencies as well. The percentage of high RSA frequencies (greater than 6.5 Hz during immobility; greater than 7.2 Hz during movement) recorded in response to the immobile stimuli was negatively correlated to the amount of RSA. Results are discussed in the light of attentional and emotional theories.