Antibiotics and probiotics-induced effects on the total fatty acid composition of feces in a rat model.

Fatty acids (FAs) play important roles as membrane components and signal transduction molecules. Changes in short chain FA (SCFA) composition are associated with gut microbiota modifications. However, the effect of bacteria-driven changes on the detailed FA spectrum has not been explored yet. We investigated the effect of antibiotics (ABx) and/or probiotics, in four treatment groups on rat stool FA composition. Principal component analysis indicated that the chromatogram profiles of the treatment groups differ, which was also observed at different time points. Linear mixed effects models showed that in the parameters compared (sampling times, treatments. and their interactions), both the weight percentage and the concentration of FAs were affected by ABx and probiotic administration. This study found that the gut microbiome defines trans and branched saturated FAs, most saturated FAs, and unsaturated FAs with less carbon atoms. These results are among the first ones to demonstrate the restoring effects of a probiotic mixture on a substantial part of the altered total FA spectrum, and also revealed a previously unknown relationship between gut bacteria and a larger group of FAs. These findings suggest that intestinal bacteria produce not only SCFAs but also other FAs that may affect the host's physiological processes.

The role of intraamygdaloid oxytocin in spatial learning and avoidance learning.

The goal of the present study is to investigate the role of intraamygdaloid oxytocin in learning-related mechanisms. Oxytocin is a neuropeptide which is involved in social bonding, trust, emotional responses and various social behaviors. By conducting passive avoidance and Morris water maze tests on male Wistar rats, the role of intraamygdaloid oxytocin in memory performance and learning was investigated. Oxytocin doses of 10 ng and 100 ng were injected into the central nucleus of the amygdala. Our results showed that 10 ng oxytocin significantly reduced the time required to locate the platform during the Morris water maze test while significantly increasing the latency time in the passive avoidance test. However, the 100 ng oxytocin experiment failed to produce a significant effect in either of the tests. Wistar rats pretreated with 20 ng oxytocin receptor antagonist (L-2540) were administered 10 ng of oxytocin into the central nucleus of the amygdala and were also subjected to the aforementioned tests to highlight the role of oxytocin receptors in spatial- and avoidance learning. Results suggest that oxytocin supports memory processing during both the passive avoidance and the Morris water maze tests. Oxytocin antagonists can however block the effects of oxytocin in both tests. The results substantiate that oxytocin uses oxytocin receptors to enhance memory and learning performance.

Novel Noninvasive Paraclinical Study Method for Investigation of Liver Diseases.

Based on a prior university patent, the authors developed a novel type of bioimpedance-based test method to noninvasively detect nonalcoholic fatty liver disease (NAFLD). The development of a new potential NAFLD diagnostic procedure may help to understand the underlying mechanisms between NAFLD and severe liver diseases with a painless and easy-to-use paraclinical examination method, including the additional function to detect even the earlier stages of liver disease. The aim of this study is to present new results and the experiences gathered in relation to NAFLD progress during animal model and human clinical trials.

Intraamygdaloid Oxytocin Increases Time Spent on Social Interaction in Valproate-Induced Autism Animal Model.

Autism spectrum disorder (ASD) is a pervasive neurodevelopmental disorder that affects about 1.5% of children worldwide. One of the core symptoms is impaired social interaction. Since proper treatment has not been found yet, an investigation of the exact pathophysiology of autism is essential. The valproate (VPA)-induced rat model can be an appropriate way to study autism. Oxytocin (OT) may amend some symptoms of ASD since it plays a key role in developing social relationships. In the present study, we investigated the effect of the intraamygdaloid OT on sham and intrauterine VPA-treated rats' social interaction using Crawley's social interaction test. Bilateral guide cannulae were implanted above the central nucleus of the amygdala (CeA), and intraamygdaloid microinjections were carried out before the test. Our results show that male Wistar rats prenatally exposed to VPA spent significantly less time on social interaction. Bilateral OT microinjection increased the time spent in the social zone; it also reached the level of sham-control animals. OT receptor antagonist blocked this effect of the OT but in itself did not significantly influence the behavior of the rats. Based on our results, we can establish that intraamygdaloid OT has significantly increased time spent on social interaction in the VPA-induced autism model, and its effect is receptor-specific.

The Role of Intra-Amygdaloid Neurotensin and Dopamine Interaction in Spatial Learning and Memory.

Neurotransmitter and neuromodulator neurotensin (NT) has been proved to facilitate spatial and passive avoidance learning after microinjected into the rat central nucleus of amygdala (CeA). These previous studies of our laboratory also revealed that neurotensin-1 receptor (NTS1) is involved in the mentioned actions of NT. Extensive literature confirms the interaction between neurotensinergic and dopaminergic systems, and our research group also suppose that the mesolimbic dopaminergic system (MLDS) is involved in the spatial learning and memory-facilitating effect of NT in the CeA. In the present work, NT and dopamine (DA) interaction has been examined in the Morris water maze and passive avoidance tests. Rats received 100 ng NT, 5 µg dopamine D2 receptor antagonist sulpiride in itself, sulpiride as a pretreatment before NT or vehicle solution into the CeA. NT microinjection significantly decreased target-finding latency in the Morris water maze test and significantly increased entrance latency in the passive avoidance test, as was expected based on our previous findings. The DA D2 receptor antagonist pretreatment was able to inhibit both effects of NT. The results confirm the facilitatory effect of NT on spatial learning and memory and let us conclude that these actions can be exerted via the DA D2 receptors.

The antipsychotic drug sulpiride in the ventral pallidum paradoxically impairs learning and induces place preference.

Sulpiride, as a D2-like dopamine (DA) receptor (D2R) antagonist, is an important antipsychotic drug in the treatment of schizophrenia. Recently, we have shown that the activation of D2Rs in the ventral pallidum (VP) modulates the activity of the ventral tegmental area (VTA) DAergic neurons. According to our hypothesis, intra-VP sulpiride can influence the motivational and learning processes, pervasively modifying the behavior of examined animals. In the present study, sulpiride was microinjected into the VP of male Wistar rats in three different doses. Morris water maze (MWM) test was applied to investigate the effects of sulpiride on spatial learning, while conditioned place preference (CPP) test was used to examine the potential rewarding effect of the drug. In order to show, whether the animals can associate the rewarding effect with an area which can be recognized only on its spatial location, we introduced a modified version of the CPP paradigm, the spatial CPP test. Our results show that the intra-VP sulpiride dose-dependently impairs learning processes. However, the largest dose of sulpiride induces place preference. Results of the spatial CPP paradigm demonstrate that the animals cannot associate the rewarding effect of the drug with the conditioning area based on its spatial location. In the CPP paradigm, locomotor activity decrease could be observed in the sulpiride-treated rats, likely because of a faster habituation with the conditioning environment. In summary, we can conclude that intra-VP sulpiride has a dual effect: it diminishes the hippocampus-dependent spatial learning processes, in addition, it has a dose-dependent rewarding effect.

Effect of D1- and D2-like Dopamine Receptor Antagonists on the Rewarding and Anxiolytic Effects of Neurotensin in the Ventral Pallidum.

BACKGROUND: Neurotensin (NT) acts as a neurotransmitter and neuromodulator in the central nervous system. It was shown previously that NT in the ventral pallidum (VP) has rewarding and anxiolytic effects. NT exerts its effect in interaction with dopamine (DA) receptors in numerous brain areas; however, this has not yet been investigated in the VP. The aim of this study was to examine whether the inhibition of D1-like and D2-like DA receptors of the VP can modify the above mentioned effects of NT. METHODS: Microinjection cannulas were implanted by means of stereotaxic operations into the VP of male Wistar rats. The rewarding effect of NT was examined by means of a conditioned place preference test. Anxiety was investigated with an elevated plus maze test. To investigate the possible interaction, D1-like DA receptor antagonist SCH23390 or D2-like DA receptor antagonist sulpiride were microinjected prior to NT. All of the drugs were also injected independently to analyze their effects alone. RESULTS: In the present experiments, both the rewarding and anxiolytic effects of NT in the VP were prevented by both D1-like and D2-like DA receptor antagonists. Administered on their own, the antagonists did not influence reward and anxiety. CONCLUSION: Our present results show that the activity of the D1-like and D2-like DA receptors of the VP is a necessary requirement for both the rewarding and anxiolytic effects of NT.

The Role of Intraamygdaloid Oxytocin and D2 Dopamine Receptors in Reinforcement in the Valproate-Induced Autism Rat Model.

BACKGROUND: autism spectrum disorder (ASD) is a neurodevelopmental disorder affecting around 1 out of 68 children and its incidence shows an increasing tendency. There is currently no effective treatment for ASD. In autism research, the valproate (VPA)-induced autism rodent model is widely accepted. Our previous results showed that intraamygdaloid oxytocin (OT) has anxiolytic effects on rats showing autistic signs under the VPA-induced autism model. METHODS: rats were stereotaxically implanted with guide cannulae bilaterally and received intraamygdaloid microinjections. In the present study, we investigated the possible role of intraamygdaloid OT and D2 dopamine (DA) receptors on reinforcement using VPA-treated rats in a conditioned place preference test. OT and/or an OT receptor antagonist or a D2 DA antagonist were microinjected into the central nucleus of the amygdala (CeA). RESULTS: valproate-treated rats receiving 10 ng OT spent significantly longer time in the treatment quadrant during the test session of the conditioned place preference test. Prior treatment with an OT receptor antagonist or with a D2 DA receptor antagonist blocked the positive reinforcing effects of OT. The OT receptor antagonist or D2 DA antagonist in themselves did not influence the time rats spent in the treatment quadrant. CONCLUSIONS: Our results show that OT has positive reinforcing effects under the VPA-induced autism rodent model and these effects are OT receptor-specific. Our data also suggest that the DAergic system plays a role in the positive reinforcing effects of OT because the D2 DA receptor antagonist can block these actions.

The D2-like Dopamine Receptor Agonist Quinpirole Microinjected Into the Ventral Pallidum Dose-Dependently Inhibits the VTA and Induces Place Aversion.

BACKGROUND: The ventral pallidum (VP) is a dopaminoceptive forebrain structure regulating the ventral tegmental area (VTA) dopaminergic population activity. We have recently demonstrated that in the VP, the D2-like dopamine (DA) receptor agonist quinpirole dose dependently facilitates memory consolidation in inhibitory avoidance and spatial learning. According to our hypothesis, quinpirole microinjected into the VP can modulate the VTA DAergic activity and influence motivation and learning processes of rats. METHODS: Quinpirole was microinjected at 3 different doses into the VP of male rats, and controls received vehicle. Single unit recordings were employed to assess VTA DAergic activity. To investigate the possible reinforcing or aversive effect of quinpirole in the VP, the conditioned place preference paradigm was used. RESULTS: Our results showed that intra-VP quinpirole microinjection regulates VTA DAergic neurons according to an inverted U-shaped dose-response curve. The largest dose of quinpirole decreased the population activity and strongly reduced burst activity of the DAergic neurons in the first hour after its application. In contrast, the 2 smaller doses increased DA population activity, but their effect started with a delay 1 hour after their microinjection. The CPP experiments revealed that the largest dose of quinpirole in the VP induced place aversion in the rats. Furthermore, the largest dose of quinpirole induced an acute locomotor activity reduction, while the medium dose led to a long-duration increase in locomotion. CONCLUSIONS: In summary, quinpirole dose dependently regulates VTA DAergic activity as well as the motivation and motor behavior of the rats at the level of the VP.

Novel probiotic treatment of autism spectrum disorder associated social behavioral symptoms in two rodent models.

The prevalence of autism spectrum disorder (ASD) has rapidly increased in the past decades, and several studies report about the escalating use of antibiotics and the consequent disruption of the gastrointestinal microbiome leading to the development of neurobehavioral symptoms resembling to those of ASD. The primary purpose of this study was to investigate whether depletion of the gastrointestinal microbiome via antibiotics treatment could induce ASD-like behavioral symptoms in adulthood. To reliably evaluate that, validated valproic acid (VPA) ASD animal model was introduced. At last, we intended to demonstrate the assessed potential benefits of a probiotic mixture (PM) developed by our research team. Male Wistar rats were used to create antibiotics treated; antibiotics and PM treated; PM treated, VPA treated; VPA and PM treated; and control groups. In all investigations we focused on social behavioral disturbances. Antibiotics-induced microbiome alterations during adulthood triggered severe deficits in social behavior similar to those observed in the VPA model. Furthermore, it is highlighted that our PM proved to attenuate both the antibiotics- and the VPA-generated antisocial behavioral symptoms. The present findings underline potential capacity of our PM to improve social behavioral alterations thus, indicate its promising therapeutic power to attenuate the social-affective disturbances of ASD.

Intraamygdaloid Oxytocin Reduces Anxiety in the Valproate-Induced Autism Rat Model.

BACKGROUND: Autism spectrum disorder (ASD) is a lifelong neurodevelopmental disorder affecting about 1.5% of children, and its prevalence is increasing. Anxiety is one of the most common comorbid signs of ASD. Despite the increasing prevalence, the pathophysiology of ASD is still poorly understood, and its proper treatment has not been defined yet. In order to develop new therapeutic approaches, the valproate- (VPA) induced rodent model of autism can be an appropriate tool. Oxytocin (OT), as a prosocial hormone, may ameliorate some symptoms of ASD. METHODS: In the present study, we investigated the possible anxiolytic effect of intraamygdaloid OT on VPA-treated rats using the elevated plus maze test. RESULTS: Our results show that male Wistar rats prenatally exposed to VPA spent significantly less time in the open arms of the elevated plus maze apparatus and performed significantly less head dips from the open arms. Bilateral OT microinjection into the central nucleus of the amygdala increased the time spent in the open arms and the number of head dips and reduced the anxiety to the healthy control level. An OT receptor antagonist blocked the anxiolytic effects of OT. The antagonist by itself did not influence the time rats spent in the open arms. CONCLUSIONS: Our results show that intraamygdaloid OT has anxiolytic effects in autistic rats.

Role of received social support in the physical activity of coronary heart patients: The Health Action Process Approach.

Physical activity (PA) plays a crucial role in the management of coronary artery disease (CAD). The Health Action Process Approach provides a useful framework for understanding and predicting the process of health behaviors. The aim of the current study was to unveil the role of received social support in the HAPA model, concerning the physical activity of CAD patients. A longitudinal sample of 117 CAD patients filled out a questionnaire during three measurement points (baseline, 2 months, and 6 months later). The constructs within the model were measured by the previously validated HAPA scales. PA was assessed with four items, which were also included in the HAPA questionnaire. To test the direct and indirect associations between the variables, structural equation modeling with latent variables was employed. Received social support was proven to have a significant and strong effect on both action planning and action control, suggesting a synergistic effect on the individual factors, as well as increasing the explained variance of PA. Results confirmed the important role of received social support in the PA of CAD patients. It could be presumed that strengthening the social support from family and friends could support the regular physical activity of CAD patients.

Effects of D2 dopamine receptor activation in the ventral pallidum on sensory gating and food-motivated learning in control and schizophrenia model (Wisket) rats.

Dopamine D2 receptors (D2Rs) of the ventral pallidum (VP) play important role in motivational and learning processes, however, their potential role in triggering schizophrenic symptoms has not been investigated, yet. In the present experiments the effects of locally administered D2R agonist quinpirole were investigated on behavioral parameters related to sensorimotor gating, motor activity and food-motivated labyrinth learning. Two weeks after bilateral implantation of microcannulae into the VP, the acute (30 min) and delayed (3, 21 and 24 h) effects of quinpirole microinjection (1 µg/0.4 µL at both sides) were investigated in Wistar and schizophrenia model (Wisket substrain) rats in prepulse inhibition (PPI) and the reward-based Ambitus tests. Quinpirole administration did not modify the impaired sensorimotor gating in Wisket rats, but it led to significant deficit in Wistar animals. Regarding the locomotor activity in the Ambitus test, no effects of quinpirole were detected in either groups at the investigated time points. In contrast, quinpirole resulted in decreased exploratory and food-collecting activities in Wistar rats with 21 and 24 h delay. Though, impaired food-related motivation could be observed in Wisket rats, but quinpirole treatment did not result in further deterioration. In summary, our results showed that the VP D2R activation in Wistar rats induces symptoms similar to those observed in schizophrenia model Wisket rats. These data suggest that Wisket rats might have significant alterations in the functional activity of VP, which might be due to its enhanced dopaminergic activity.

Disturbance of taste reactivity and other behavioral alterations after bilateral interleukin-1ß microinjection into the cingulate cortex of the rat.

The anterior cingulate cortex (ACC), is known to be intimately involved in food-related motivational processes and their behavioral organization, primarily by evaluating hedonic properties of the relevant stimuli. In the present study, the involvement of cingulate cortical interleukin-1ß (IL-1ß) mediated mechanisms in a) gustation associated facial and somato-motor behavioral patterns of Wistar rats were examined in taste reactivity test (TR). In addition, b) conditioned taste aversion (CTA) paradigm was performed to investigate the role of these cytokine mechanisms in taste sensation associated learning processes, c) the general locomotor activity of the animals was observed in open field test (OPF), and d) the potentially negative reinforcing effect of IL-1ß was examined in conditioned place preference test (CPP). During the TR test, species specific behavioral patterns in response to the five basic tastes were analyzed. Response rates of ingestive and aversive patterns of the cytokine treated and the control groups differed significantly in case of the weaker bitter (QHCl, 0.03 mM), and the stronger umami (MSG, 0.5 M) tastes. IL-1ß itself did not elicit CTA, it did not interfere with the acquisition of LiCl induced CTA, and it also failed to cause place preference or aversion in the CPP test. In the OPF paradigm, however, significant differences were found between the cytokine treated and the control groups in the rearing and grooming, the number of crossings, and in the distance moved. Our results indicate the involvement of cingulate cortical IL-1ß mechanisms in the control of taste perception and other relevant behavioral processes.

Cognitive performance of the MAM-E17 schizophrenia model rats in different age-periods.

Cognitive disturbances are among the most important features of schizophrenia, and have a significant role in the outcome of the disease. However, the treatment of cognitive symptoms is poorly effective. In order to develop new therapeutic opportunities, the MAM-E17 rat model of schizophrenia can be an appropriate implement. In the present study we investigated several cognitive capabilities of MAM-treated rats using radial arm maze (RAM) task, which corresponds to the recent research directives. Because of the diachronic appearance of schizophrenia symptoms and the early appearance of cognitive deficiencies, we carried out our experiments in three different age-periods of rats, i.e. in prepuberty, late puberty and adulthood. The performance of MAM-E17 rats was similar to control rats in the acquisition phase of RAM task, except for puberty. However, after rearrangement of reward positions (in the reverse paradigm) the number of errors of MAM-treated rats was higher in each age-period. In the reverse paradigm MAM-treated groups visited more frequently those non-rewarding arms, which were previously rewarding. Our results suggest that working memory of MAM-E17 rats is impaired. This deficit depends on the difficulty of the task and on the age-period. MAM-E17 rats seem to be more sensitive in puberty in comparison to controls. Diminished behavioral flexibility was shown as well. These behavioral results observed in MAM-E17 rats were similar to those of cognitive deficiencies in schizophrenia patients. Therefore, MAM-E17 model can be a useful implement for further research aiming to improve cognition in schizophrenia.

Determination of frail state and association of frailty with inflammatory markers among cardiac surgery patients in a Central European patient population.

INTRODUCTION: With the aging of the population, the screening of frail patients, especially before high-risk surgery, come to the fore. The background of the frail state is not totally clear, most likely inflammatory processes are involved in the development. METHODS: Our survey of patients over age of 65 who were on cardiac surgery were performed with Edmonton Frail Scale (EFS). Patients' demographic, perioperative data, incidence of complications and correlations of inflammatory laboratory parameters were studied with the severity of the frail state. RESULTS: On the basis of EFS, 313 patients were divided into non-frail (NF,163,52%), pre-frail (PF,89,28.5%) and frail (F,61,19.5%) groups. Number of complications in the three groups were different (NF:0.67/patient, PF:0.76/patient, F:1.08/patient). We showed significant difference between NF and F in both intensive care and hospital stay, but there was no statistical difference between the groups in hospital deaths (NF:5/163, PF:3/89, F:5/61). We also found a significant difference between NF and F patients in preoperative fibrinogen-, CRP- and white blood cell count levels. CONCLUSIONS: We first present the incidence of frailty in patients with heart surgery in a Central-European population. According to our results, inflammatory processes are likely to play a role in the development of the frail state.

QRFP administration into the medial hypothalamic nuclei improves memory in rats.

Even though several of RFamide peptides have been shown to modify memory and learning processes in different species, almost nothing is known regarding cognitive effects of recently discovered neuropeptide QRFP. Considering multiple physiological functions of QRFP, localization of QRFP-synthesizing neurons in the hypothalamus and its' widely spread binding sites within the CNS, the present study was designed to investigate the possible role of QRFP in the consolidation of spatial memory. As target area for microinjection, the medial hypothalamic area, including dorsomedial (DMN) and ventromedial (VMN) nuclei, has been chosen. At first, the effects of two doses (200 ng and 400 ng) of QRFP were investigated in Morris water maze. After that receptor antagonist BIBP3226 (equimolar amount to the effective dose of neuropeptide) was applied to elucidate whether it can prevent effects of QRFP. To reveal possible changes in anxiety level, animals were tested in Elevated plus maze. The higher dose of QRFP (400 ng) improved short-term memory consolidation in Morris water maze. Pretreatment with antagonist BIBP3226 abolished cognitive effects of QRFP. The neuropeptide did not affect anxiety level of rats. This study provides unique evidence regarding the role of QRFP in the consolidation of memory and gives the basis for further investigations of neuropeptide's cognitive effects.

Characterization of lymphocyte subpopulations and cardiovascular markers in pericardial fluid of cardiac surgery patients.

BACKGROUND: Composition of pericardial fluid (PF) may reveal immunological processes influencing oxidative stress and microcirculation of different tissues of the heart and may play a role in the course of myocardial infarction, atherosclerosis, and aortic stenosis. PATIENTS AND METHODS: We investigated lymphocyte populations, cardiovascular markers and immunoglobulin composition in PF and blood samples of patients undergoing CABG operation and compared them to those who had aortic valve surgery. RESULTS: The amount of CD8 + T, NK, memoT and activated T-cytotoxic cells were elevated in PF compared to blood, but naiveT and activated T-helper cell ratio were lower in PF. Amount of activated T-helper cells and regulatory T-lymphocytes were elevated in CABG participants in both PF and blood. INKT cells represented the only regulatory lymphocyte population reaching significantly higher concentration in PF than in blood. IL-6 and MCP1 level were elevated in PF compared to blood and MCP1 plasma level was markedly elevated in CABG group. CONCLUSIONS: Our study describes a comprehensive immunological analysis of PF in humans for the first time. We showed that the investigated lymphocyte populations and cardiovascular markers in PF have significantly different distribution compared to blood, and lymphocyte populations show different compartmentization in coronary disease and aortic stenosis.

Ventromedial prefrontal cortex is involved in preference and hedonic evaluation of tastes.

The ventromedial prefrontal cortex (vmPFC) of rats has reciprocal connections with the gustatory and the hedonic impact coding structures. The main goal of the present study was to investigate the involvement of local neurons of vmPFC and their catecholaminergic innervations in taste preference and taste reactivity test. Therefore, kainate or 6-hydroxydopamine (6-OHDA) lesions were performed in the vmPFC by iontophoretic method. In the first experiment, taste preference was tested to 250 mM and 500 mM glucose solutions over water in two-bottle choice test. In the second experiment, taste reactivity was examined to 4 concentrations of glucose solutions (250 mM, 500 mM, 750 mM and 1000 mM) and 4 concentrations of quinine solutions (0.125 mM, 0.25 mM, 1.25 mM and 2.5 mM). Our results showed, that kainate microlesion of vmPFC did not modify the preference of 250 mM and 500 mM glucose solutions in two-bottle choice test. In contrast, 6-OHDA microlesion of vmPFC resulted in increased preference to the higher concentration of glucose (500 mM) solution over water. Results of taste reactivity test showed that kainate lesion resulted in more ingestive and less rejective responses to 750 mM glucose solution and elevated rejectivity to the higher concentrations (1.25 mM and 2.5 mM) of quinine solutions. 6-OHDA lesion of vmPFC increased the number of ingestive responses to highly concentrated (500 mM, 750 mM and 1000 mM) glucose solutions and decreased the number of ingestive responses to the lower concentration (0.125 mM) of quinine solution. The present data provide evidence for the important role of vmPFC neurons and catecholaminergic innervation of the vmPFC in the regulation of hedonic evaluation of tastes and in the hedonic consummatory behavior.

The role of social support in the dietary behavior of coronary heart patients: an application of the health action process approach.

Dietary behaviour plays a crucial role in both the onset and the management of coronary artery disease (CAD). To develop effective interventions to modify dietary behaviours of patients, it is fundamental to identify and examine the predictive factors that are relevant to healthy dietary behaviour. The Health Action Process Approach provides a useful framework for understanding and predicting the process of health behaviour. The aim of the current study is to clarify the role and effect of received social support in the HAPA model. A longitudinal sample of 117 CAD patients filled out a questionnaire at three time points. Along with HAPA constructs, dietary behaviour was assessed with a food frequency questionnaire. To investigate the longitudinal associations of the constructs, structural equation modelling with latent variables was employed. In the final model, outcome expectancies and pre-action self-efficacy jointly predicted behavioural intention. In the post-intentional phase, social support served as a mediator between intention and action planning. Moreover, coping planning mediated the relationship between action planning and dietary behaviour. These results confirmed the mediator role of social support in the intention-behaviour relationship. This finding suggests that social support can be a crucial component to facilitate healthy dietary behaviour.