Acute Stress Situations Research Articles

Evaluation of immune and stress status in harbour porpoises (Phocoena phocoena): can hormones and mRNA expression levels serve as indicators to assess stress?

BackgroundThe harbour porpoise is exposed to increasing pressure caused by anthropogenic activities in its marine environment. Numerous offshore wind farms are planned or under construction in the North and Baltic Seas, which will increase underwater noise during both construction and operation. A better understanding of how anthropogenic impacts affect the behaviour, health, endocrinology, immunology and physiology of the animals is thus needed. The present study compares levels of stress hormones and mRNA expression of cytokines and acute-phase proteins in blood samples of harbour porpoises exposed to different levels of stress during handling, in rehabilitation or permanent human care.Free-ranging harbour porpoises, incidentally caught in pound nets in Denmark, were compared to harbour porpoises in rehabilitation at SOS Dolfijn in Harderwijk, the Netherlands, and individuals permanently kept in human care in the Dolfinarium Harderwijk and Fjord & Belt Kerteminde, Denmark. Blood samples were investigated for catecholamines, adrenaline, noradrenaline and dopamine, as well as for adrenocorticotropic hormone (ACTH), cortisol, metanephrine and normetanephrine. mRNA expression levels of relevant cell mediators (cytokines IL-10 and TNFα, acute-phase proteins haptoglobin and C-reactive protein and the heat shock protein HSP70) were measured using real-time PCR.ResultsBiomarker expression levels varied between free-ranging animals and porpoises in human care. Hormone and cytokine ranges showed correlations to each other and to the health status of investigated harbour porpoises. Hormone concentrations were higher in free-ranging harbour porpoises than in animals in human care. Adrenaline can be used as a parameter for the initial reaction to acute stress situations; noradrenaline, dopamine, ACTH and cortisol are more likely indicators for the following minutes of acute stress. There is evidence for different correlations between production of normetanephrine, metanephrine, cortisol and the expression of IL-10, HSP70 and haptoglobin.ConclusionsThe expression patterns of the selected molecular biomarkers of the immune system are promising to reflect the health and immune status of the harbour porpoise under different levels of stress.

A retrospective evaluation of informed consent for tissue donation within a year of the donor's death

By German law organ and tissue donation may only be done if explicit consent is given during lifetime, e.g. by a donor card, or if the family grants informed consent after death in line with the deceased's last will, what is discussed to mean an additional emotional load in the situation of mourning.Every year about 35 musculoskeletal tissue donations and 250 donations of corneoscleral discs (means 125 donors) are performed in the Hamburg Institute of Legal Medicine. Talking to the next of kin plays a key role in the consenting process for donation. We show our guidelines according to the family contact by telephone and present the results of a catamnestic review referring to the donors of one year's period. Methods: One year after procurement had been completed we requested the consenting person to answer a questionnaire and asked for an evaluation of the contact to the institute's coordinator and furthermore the emotional impact of the consenting process. Results: 26 (72.2% of 36 only musculoskeletal donors) and 77 (73.3% of 114 only cornea donors) consenting persons answered and gave a positive feedback in the dimensions of information, support and consent. Discussion: The telephone contact with families of deceased persons out of the Institute of Legal Medicine is perceived to be helpful in an acute stress situation caused by a sudden death and an accepted way to establish the deceaseds’ wishes in respect to donation through the relatives. Conclusion: According to the letter of the German Transplantation Act asking for donation is an obligation for every physician and our data show that this means no additional burden for relatives, if the question is placed appropriately. Forensic institutes play a key role in the recognition of tissue donors and take up the challenge to act as an interface between donors and recipients. But caring for the sufficient supply with tissue transplants needs considerable resources. Therefore additional support is necessary to fulfill this task.

Measurement of chromogranin A in porcine saliva: validation of a time-resolved immunofluorometric assay and evaluation of its application as a marker of acute stress

The objective of this study was to develop and validate a time-resolved immunofluorometric assay (TR-IFMA) for porcine salivary chromogranin A (CgA) measurements, using a species-specific antibody, and evaluate its behaviour in an acute stress model. Polyclonal antibodies were produced in rabbits immunized with a synthetic porcine fragment of CgA359−379 and used to develop a sandwich TR-IFMA. This TR-IFMA was analytically validated and showed intra- and inter-assay coefficients of variation of 6.23% and 5.82%, respectively, an analytical limit of detection of 4.27 × 10−3 μg/ml and a limit of quantification of 24.5 × 10−3 μg/ml. The assay also demonstrated a high level of accuracy, as determined by linearity under dilution (r = 0.975) and recovery tests. When a model of experimental acute stress, in which animals were immobilized for 3 min with a nose snare (stressor stimulus), was applied, a significant increase (P < 0.05) in CgA levels in saliva was detected at 15 min post-stressor stimulus. These results indicate that the assay developed in this study could measure CgA in porcine saliva in a reliable way and that the concentrations of CgA in saliva samples of pigs increase after an acute stress situation.

Risk Factors for Stroke: Data from the Register of a Large Industrial City in Western Siberia

This study is based on the results of complex clinical, instrumented, laboratory, and statistical studies. A total of 538 patients ‐ 280 men (52.0%) and 258 women (48.0%), aged 25‐74 years ‐ with stroke were studied; all were permanent inhabitants of the territory of Novosibirsk. Patients were distributed by age as follows: 24 patients (4.2%) were young (13 (2.2%) male, 11 (2.0%) female); 185 patients (34.8%) were of middle age (114 (21.4%) male, 71 (13.4%) female), and 329 patients (61.0%) were elderly (153 (28.4%) male, 176 (32.6%) female). The incidence of arterial hypertension (AHT) was 98.9%, with identical frequencies in men and women. The incidence of smoking was significantly greater among men (71.6%) than women (6.2%) (p < 0.001). The incidence of heart disease was 54.3%, with essentially equal frequencies among men (54%) and women (54.6%). The incidence of atrial fibrillation (AF) was 13%. There were no significant differences in the incidences of AF between men (12.5%) and women (13.6%). Signs of myocardial infarction (MI) were present in 9.7% of patients (12.8% of men and 6.2% of women; p < < 0.01). The incidence of dyslipoproteinemia (DLP) was 57.4%, with a higher incidence among women (61.2%) than men (54%) (p < 0.05). Diabetes mellitus (DM) was present in 14.5% of patients, more commonly in women (22.5%) than men (7.1%) (p < 0.001). Acute and chronic stress situations during the premorbid period were present in 22.9% of patients, more frequently among men than women (28.6% and 16.7%, respectively; p < 0.05). Thus, the leading risk factors in men were AHT (98.9%), smoking (76.1%), heart disease (54%), DLP (54%), and stress (28.6%). The proportion of patients with AHT increased with age, reaching 100% among elderly patients. Attention is drawn to the significant predominance of the smoking factor among men in the young group (92.3%).

Stress induces a functional asymmetry in an emotional attention task

Anxiety is associated with an attentional bias towards angry faces. This effect is most pronounced when the face is presented in the left visual hemifield (LVHF), suggestive of a right hemisphere involvement. Little is known about the modulation of this attentional bias in situations of acute stress. In the current study 38 male participants were randomly allocated to a stress (Trier Social Stress Test; TSST) or a non-stressful control condition. Afterwards they performed an emotional dot-probe paradigm. Stress induced negative affect and a rise in salivary cortisol. Stress caused a pattern of functional asymmetry in the short stimulus onset asynchrony (SOA) interval, which was absent in the control group. Stressed participants responded faster to angry faces presented to the LVHF, but responded faster to happy faces presented to the right VHF. This could suggest that stress influences interhemispheric transfer of information that is relevant for emotion processing.

The Effect of Self-esteem on Psychobiological Stress Response under Acute Stress Situation

The Effect of Self-esteem on Psychobiological Stress Response under Acute Stress Situation

The impact of stress systems and lifestyle on dyslipidemia and obesity in anxiety and depression

Dyslipidemia and obesity have been observed in persons with severe anxiety or depression, and in tricyclic antidepressant (TCA) users. This likely contributes to the higher risk of cardiovascular disease (CVD) in anxiety and depressive disorders. We aimed to elucidate whether biological stress systems or lifestyle factors underlie these associations. If so, they may be useful targets for CVD prevention and intervention. Within 2850 Netherlands Study of Depression and Anxiety (NESDA) participants, we evaluated the explaining impact of biological stress systems (i.e., the hypothalamic-pituitary-adrenal [HPA] axis, autonomic nervous system [ANS] and inflammation) and lifestyle factors (i.e., tobacco and alcohol use, and physical activity) on adverse associations of anxiety and depression severity and TCA use with high and low-density lipoprotein cholesterol, triglycerides, body mass index and waist circumference. Through linear regression analyses, percentual change (%Δ) in β was determined and considered significant when %Δ>10. The inflammatory marker C-reactive protein had the most consistent impact (explaining 14-53% of the associations of anxiety and depression severity and TCA use with lipid and obesity levels), followed by tobacco use (explaining 34-43% of the associations with lipids). The ANS mediated all associations with TCA use (explaining 32-61%). The HPA axis measures did not explain any of the associations. Increased dyslipidemia and (abdominal) obesity risk in patients with more severe anxiety disorders and depression may be partly explained by chronic low-grade inflammation and smoking. TCAs may increase metabolic risk through enhanced sympathetic and decreased parasympathetic ANS activity. That the HPA axis had no impact in our sample may reflect the possibility that the HPA axis only plays a role in acute stress situations rather than under basal conditions.

Stress responses and decision making in child protection workers faced with high conflict situations

IntroductionThe assessment of children at risk of abuse and neglect is a critical societal function performed by child protection workers in situations of acute stress and conflict. Despite efforts to improve the reliability of risk assessments through standardized measures, available tools continue to rely on subjective judgment. The goal of this study was to assess the stress responses of child protection workers and their assessments of risk in high conflict situations. MethodsNinety-six child protection workers participated in 2 simulated scenarios, 1 non-confrontational and 1 confrontational. In each scenario, participants conducted a 15-minute interview with a mother played by a specially trained actor. Following the interview, the workers completed 2 risk assessment measures used in the field at the time of the study. Anxiety was measured by the State-Trait Anxiety Inventory at baseline and immediately following the completion of each interview. Physiological stress as measured by salivary cortisol was obtained at baseline as well as 20 and 30minutes after the start of each interview. ResultsParticipants demonstrated significant stress responses during the 1st scenario, regardless of whether the interview was confrontational or not. During the second scenario, the participants did not exhibit significant cortisol responses, however the confrontational interview elicited greater subjective anxiety than the non-confrontational scenario. In the first scenario, in which the workers demonstrated greater stress responses, risk assessment scores were higher on one risk assessment tool for the confrontational scenario than for the non-confrontational scenario. ConclusionThe results suggest that stress responses in child protection workers appear to be influenced by the novelty of a situation and by a parent's demeanor during interviews. Some forms of risk assessment tools appear to be more strongly associated than other with the workers’ subjective and physiological stress responses. This merits further research to determine which aspects of risk assessment tools are susceptible to the emotional elements of intake interviews.

Coping strategies as mediators of the relationship between sense of coherence and stress reactions: Israeli adolescents under missile attacks

This study aimed to explore the relationships between sense of coherence (SOC) and stress reactions as mediated by cognitive appraisal and coping strategies among adolescents facing the acute stressful situation of missile attacks. Employing the Salutogenic Model and the interactionist approach to coping, we asked what the roles of situational factors such as coping strategies and cognitive appraisal were in mediating the relationship between SOC and stress reactions. Data were gathered during January 2009 when hundreds of missiles fell in southern Israel. One hundred and thirty eight adolescents filled out questionnaires dealing with SOC, cognitive appraisal (endangerment feelings), Adolescent Coping Scale, state anxiety, state anger, and psychological distress. Overall, our model explained 55% of the variance in stress reactions. SOC had the strongest total direct and indirect effects. Previous findings have indicated SOC as playing only a limited role in explaining stress reactions in acute stress situations. The results of this study highlight the potential of SOC as a powerful resilience factor even in an acute situation, through mediation of situational factors.

Cardiac survival strategies: an evolutionary hypothesis with rationale for metabolic therapy of acute heart failure

ABSTRACT Acute coronary occlusion, causing a heart attack, is best treated by prompt intervention and re-opening of the blocked artery. Such acute reperfusion, although saving many threatened heart cells from death, also paradoxically causes lethal reperfusion injury due to calcium overload in the mitochondria. There are protective molecular rescue paths that lessen the extent of such reperfusion injury. We discuss the evolution of these pathways during primitive times when heart attacks were rare. We believe that these paths evolved to counter acute stress situations in our ancestors when stimulated by intense physical effort, environmental conditions or hunting hazards, often accompanied by blood loss and hypotension. To test our hypothesis, we developed an underperfused model of acute heart failure with low perfusion pressure in the isolated rat heart to simulate the hypotensive response. We also increased the contents of free fatty acids (FFA) in the perfusate to supraphysiological levels to mimic the rapid fear-driven elevation of FFA in the hunter. FFA have a deleterious effect on a failing heart while glucose is proposed as protecting the acutely failing heart. We found that glucose given to the acutely failing heart improved the functional recovery by increasing the heart rate and contractility. We hypothesise that similar metabolic principles may protect against acute heart failure as against regional ischemia with lethal injury. We further suggest that the requirement for protection against acute stress in primitive persons led to the evolution of the molecular pathways now known to protect from lethal reperfusion injury.

Prolactin is Involved in the Systemic Inflammatory Response in Myocardial Infarction

Prolactin may contribute to an atherogenic phenotype. Furthermore, previous studies have shown that prolactin levels increase in situations of acute stress and inflammation. We therefore aimed to investigate the relationship between prolactin, acute stress and inflammation in patients with myocardial infarction. We performed a case-control study in 40 patients with myocardial infarction and 39 controls, aged 41-84 years. Blood for assessment of prolactin and high sensitive C-reactive protein (hsCRP) was drawn at inclusion, that is, during the acute phase of the event, and 2-3 weeks later. Unexpectedly, prolactin levels at inclusion did not differ between cases and controls (7.0 ng/ml and 6.0 ng/ml, respectively, p=0.28). 2-3 weeks later prolactin levels in cases had not decreased. However, univariate regression analysis indicated that hsCRP is associated with prolactin levels (regression coefficient β 0.11; [95% CI 0.01; 0.21]; p=0.03) in cases during the acute phase of myocardial infarction. Our findings may suggest that prolactin is involved in the systemic inflammatory response, which takes place during myocardial infarction; however, this association may not be strong enough to induce higher prolactin levels in patients with myocardial infarction.

Chronic URB597 treatment at adulthood reverted most depressive-like symptoms induced by adolescent exposure to THC in female rats

We have recently shown that chronic THC administration in adolescent female rats induces subtle but lasting alterations in the emotional circuit ending in depressive-like behaviour at adulthood. Here we describe other relevant depressive-like symptoms present in these animals. Adult female rats pretreated with THC display passive coping strategy towards acute stressful situations as demonstrated by their behaviours in the first session of the forced swim test, develop a profound anhedonic state as demonstrated by the reduced consumption of palatable food and present a decrease in social functioning. Besides the emotional symptoms, adolescent exposure to THC induced a significant deficit in object recognition memory. Since it has been reported that deficits in adult hippocampal neurogenesis may underlie the cognitive dysfunction seen in depression, we then survey cell proliferation in the dentate gyrus of the hippocampus. Adolescent THC exposure significantly reduced the number of BrdU-positive cells in THC-treated rats as well as hippocampal volume. We suggest that this complex depressive-like phenotype is triggered by a long-lasting decrease in CB1 receptor functionality in specific brain regions. To test whether an increase in the endocannabinoid signalling could ameliorate the depressive phenotype, adult female rats pre-exposed to THC were injected with URB597 (0.3mg/kg ip) and then tested in behavioural assays. URB597 was able to reverse most depressive-like symptoms induced by adolescent THC exposure such as the passive coping strategy observed in THC exposed animals in the forced swim test as well as anhedonia and the reduced social activity.These results support a role for the endocannabinoid system in the neurobiology of depression and suggest the use of URB597 as a new therapeutic tool with antidepressant properties.

Prefrontal cortex, caloric restriction and stress during aging: Studies on dopamine and acetylcholine release, BDNF and working memory

This study was designed to investigate whether long-term caloric restriction during the life span of the rat changes the effects of an acute mild stress on the release of dopamine and acetylcholine in the prefrontal cortex (PFC) and on working memory performance. Spontaneous motor activity was also monitored and levels of BDNF measured in the prefrontal cortex, amygdala and hippocampus. Male Wistar rats (3 months of age) were housed during 3, 12, 21 and 27 months (6, 15, 24 and 30 months of age at the end of housing) in caloric restriction (CR; 40% food intake restriction) or control conditions. After behavioural testing, animals were further subdivided into two other groups. In one of the groups BDNF protein levels were determined. In the other group rats were implanted with guide cannulas into the PFC to perform microdialysis experiments. In CR rats the release of dopamine produced by handling stress did not differ from the response found in control rats of 6, 15 and 24 months of age. The release of acetylcholine was not changed at the ages of 6 and 15 months but reduced at the age of 24 months. Stress did not change dopamine or acetylcholine release in CR and control rats of 30 months of age. BDNF levels were increased in the hippocampus and amygdala, but not in the PFC, of 6 and 15 months CR rats. Spontaneous motor activity was increased in all groups of CR rats. Age, however, decreased motor activity in CR and control rats. Both experimental groups showed similar working memory performance in a delayed alternation task in basal conditions and after a situation of acute stress. These results suggest that CR does not modify the function of the PFC in response to an acute stress nor the changes found as a result of the normal process of aging.

Coping Resources as Explanatory Factors of Stress Reactions During Missile Attacks: Comparing Jewish and Arab Adolescents in Israel

The aim of this study was to explore coping resources as explanatory factors in reducing emotional distress of adolescents in an acute stress situation. We compared two ethnic groups-Jewish and Arab-Bedouin Israelis-during intensive missile attacks in January 2009. Data were gathered from 138 Israeli-Jews and 84 Israeli-Arab Bedouins, 12-18years old, who filled out self reported questionnaires among which state anxiety, state anger, and psychological distress (SPD) were measures of emotional distress, and sense of coherence (SOC) and hope index served as measures of coping resources. Findings indicated no differences between the two groups on state anxiety, SPD and hope levels. Arab Bedouins reported higher levels of state anger and lower levels of sense of coherence. The coping resources, however, explained the stress reactions differently among the two groups. While SOC made a major contribution in explaining stress reactions among Jewish adolescents, hope index explained stress reactions only for the Arab group. The findings are discussed against the background of the salutogenic theory and the cultural differences between the two ethnic groups.

Impact of glucocorticoids on brain function: Relevance for mood disorders

Exposure to stressful situations activates two hormonal systems that help the organism to adapt. On the one hand stress hormones achieve adaptation by affecting peripheral organs, on the other hand by altering brain function such that appropriate behavioral strategies are selected for optimal performance at the short term, while relevant information is stored for reference in the future. In this chapter we describe how cellular effects induced by stress hormones--in particular by glucocorticoids--may contribute to the behavioral outcome after a single stressor. In addition to situations of acute stress, chronic uncontrollable and unpredictable stress also exerts profound effects on structure and function of limbic neurons. The impact of chronic stress is not a mere cumulative effect of what is seen after acute stress exposure. Dendritic trees are expanded in some regions but reduced in others. In general, cells are exposed to a higher calcium load upon depolarization, but show attenuated responses to serotonin. Synaptic strengthening is largely impaired. In this viewpoint we speculate how cellular effects after chronic stress may be maladaptive and could contribute to the development of psychopathology in genetically vulnerable individuals.

Environmental enrichment, prefrontal cortex, stress, and aging of the brain

As a result of living in an enriched environment, the brain of animals undergoes molecular and morphological changes leading to improvements in learning and memory. These improvements correlate well with increase in neurogenesis, synaptic density, or neurotrophic factors. We review here, in the context of the literature, the experiments performed in our own laboratory on the effects of environmental enrichment on the dynamics of dopamine and acetylcholine in the prefrontal cortex under a situation of acute mild stress. In these last studies we found that the release of dopamine and acetylcholine under stress is reduced in animals housed in an enriched environment. We also reported that the stress-induced release of dopamine but not acetylcholine is lower in aged rats compared with young rats. These results suggest that environmental enrichment reduces the reactivity to stress of the prefrontal dopaminergic and cholinergic systems in the rat. We further hypothesize that the positive effects on stress coping behaviors of housing animals in an enriched environment are associated with reductions, rather than increases, in the release of dopamine and acetylcholine in the prefrontal cortex. Finally we propose that a reduction in the stress-induced release of dopamine observed during aging in control animals might be an index of a better adaptation to stressful stimuli.

Cardioprotective effect of EGb 761 on myocardial ultrastructure of young and old rat heart and antioxidant status during acute hypoxia

Acute hypoxia is a threatening clinical case of emergency and may result in ultrastructural damage, with complete loss of cellular and organ functions. However, little is known about the differences in hypoxia tolerance between young and old myocardia and the protective effects of radical scavenging agents in acute hypoxic stress situations. We investigated the age-dependent differences of the myocardial ultrastructure and antioxidative status (superoxide-dismutase (SOD) activity and malondialdehyde (MDA) content) of young (6 months) and old (22-24 months) Wistar rats (Crl (Wi)Br) after acute respiratory hypoxia of 20 min at 5% v/v O2 in N2O mixture, and the protective effect of Ginkgo biloba extract (EGb 761). Ultrastructural-morphometric and biochemical age analysis only revealed a decrease in the sarcoplasma volume fraction, an increase in homogeneous intramitochondrial areas, significant higher SOD activity and lower MDA levels in the group of old rats. Pretreatment with EGb 761 led to a significant decrease in MDA content in both control groups. Acute hypoxic stress increased the volume fractions of sarcoplasmatic reticulum, t-tubules, vacuoles, and lipid droplets, and caused mitochondrial swelling, with a more significant increase in degenerated and homogeneous intramitochondrial areas in the old group. SOD activity decreased only in the old hypoxic group; MDA content fell in both. Pretreatment with EGb 761 reduced ultrastructural-morphometric hypoxic damage in both groups, significantly below the levels of control. Young rat myocardium showed significantly higher SOD activity after hypoxia than untreated or older specimens. Better hypoxia tolerance is demonstrated by the young myocardium, and an obvious hypoxia-protective effect of EGb 761 in both age groups.

Previous Trauma Exposure and PTSD Symptoms as Predictors of Subjective and Biological Response to Stress

The immediate and long-term effects of traumatic exposure and subsequent posttraumatic stress reactions in people in high-risk occupations are well-documented. What is less evident is the impact of this traumatic exposure and subsequent traumatic stress symptoms on workers' response to acute stress situations. This study aimed to examine the association between prior traumatic exposure related to policing, current posttraumatic stress symptoms and biological markers of stress, and subjective appraisal of stress before, during, and after exposure to acutely stressful stimuli. A stressful policing situation was created through the use of a video simulator room. Participants' responses to the simulated emergency were evaluated by monitoring heart rate, collecting salivatory samples for cortisol analysis, and repeated administration of a subjective measure of anxiety. Biological indicators of stress, as measured by cortisol level and heart rate, were not associated with previous trauma exposure or trauma symptoms; however, biological response was associated with subjective anxiety. Vulnerability to psychological stress responses during an acute stress situation was also associated with lower levels of social support, previous traumatic exposures, and preexisting symptoms of traumatic stress. The importance of these factors became more pronounced as time progressed after the event. Previous trauma exposure did not put individuals at increased risk of biological distress during an acute stress situation. However, previous trauma and reduced social supports were associated with continuing psychological distress, confirming previous research and raising concerns about the cumulative negative effects of traumatic exposure on psychological health in emergency responders.

Humic substances

Changing environmental conditions and handling stress are well known to cause chronic or acute stress situations in fish with subsequent infections. These requires a therapy by means of antibiotics and chemicals. In contrast to the huge number of pathogens, only a few substances are permitted for application as therapeutics in German aquaculture. Hence, there emerges an urgent need for highly effective and residueless alternatives. The prophylactic stimulation and training of the defense system of fish by alternative approaches becomes increasingly necessary. One approach is the application of dissolved humic substances (HS) of natural or artificial origin. For example, there exist several reports on the positive effect of HS to fishes. These effects shall be considered in detail. Furthermore, the impact of HS on the constitution of parasites and pathogens will be displayed. The reports on this issue are diverse, if not inconsistent. We try to shed some light on these discrepancies. The last aspect covered by this review is the outdated paradigm that calcium ions act as antidotes. In the presence of HS, even the opposite effect may occur. To overcome old paradigms on HS and their potential interactions with fish and fish parasites, we reviewed recent international literature, as well as 'grey' literature. We also include results from own former and ongoing studies. HS are able to increase the physiological condition of the individuals and to reduce adverse physiological and histological consequences caused by stress; the mechanism behind remains obscure. HS detoxify heavy metals and organic pollutants. Damages caused by several fish pathogens, such as bacteria and parasites, can be repaired more quickly in the presence of HS. Some parasites--mainly fungi--appear to be directly affected by HS. Comparing the fungicidal effects of HS from various sources, evidence is increasing that the aliphatic moiety may be the effective structures. However, further research is necessary to relate more physiological and anti-pathogenic effects to the chemical characteristics of HS. HS are not real alternatives to strong traditional therapeutics. However, they show different advantages in repairing secondary, stress induced damages in fish. The ecophysiological relevance of HS in either aquatic systems or aquaculture is getting conspicuously. The lack of therapeutic and antiparasitic substances in aquaculture requires new strategies and ways of thinking. The search for alternatives to the 'traditional' chemical therapeutics calls for the intensive research. Inevitably, this search will lead to an intensive contemplation on HS as 'health promoting substances' and/or even therapeutics. Basic research is needed to detect the functional groups of the HS responsible for the effects observed. Health promoting effects of first investigations made in vitro to affect pathogens via application of HS and several field studies with HS raises hopes for a broader utilisation of HS to reduce stress consequences in fish and fish pathogens residuelessly.

Effects of swim stress on mRNA and protein levels of steroid 5α-reductase isozymes in prefrontal cortex of adult male rats

The metabolite of progesterone, allopregnanolone, is among the most potent known ligands of the γ-aminobutyric acid receptor complex (GABA A-R) in the central nervous system. This neuroactive steroid is markedly increased in an animal model of acute stress. Allopregnanolone is synthesized from progesterone by steroidogenic enzymes 5α-reductase (5α-R) and 3α-hydroxysteroid dehydrogenase (3α-HSD), with the former being the rate-limiting enzyme in this reaction sequence. In this paper, a quantitative RT-PCR method coupled to laser-induced fluorescence capillary electrophoresis (LIF-CE) and Western blot were used to measure both mRNA and protein levels of 5α-R type 1 (5α-R1) and 5α-R type 2 (5α-R2) isozymes in prefrontal cortex of male rats after acute swim stress situations. Our results demonstrate that both 5α-R isozymes are significantly higher in prefrontal cortex of male rats after acute swim stress in comparison with control rats. These data may open up a new research line that could improve our understanding of the role of 5α-R isozymes in processes that accompany stress situations.