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PubMed2000

Neuropeptide-Y exerts antidepressant-like effects in the forced swim test in rats.

The effects of neuropeptide-Y were examined in the forced swim model of depression in rats. Following a 15-min preswim, four groups of rats were given three intracerebroventricular (i.c.v.) injections of neuropeptide-Y (0.5, 5, or 10 microg) or saline over a 24-h period. Several behaviors were subsequently measured during a 5-min forced swim. Neuropeptide-Y treatment dose dependently increased swimming and decreased immobility. The pattern of results is consistent with that produced by serotonergic antidepressant drugs in this model.

Animals↗
PubMed2001

Improved accuracy and reliability of sweepback angle, pitch angle and hand velocity calculations in swimming.

The estimation of forces in swimming using the quasi-static approach (Schleihauf, In: J. Terauds, J.P. Clarys (Eds.), Swimming III, International Series on Sports Sciences. Vol. 8, University Park Press, Baltimore, 1979, 70-109) has been popular in recent years as propulsion is an important determinant of performance. The aim of this study was to establish the accuracy and reliability of current and newly proposed procedures for the reconstruction of hand velocity, sweepback angle and pitch angle from underwater three-dimensional video analysis. A full-scale mechanical arm capable of simulating a controlled and highly repeatable underwater phase of the front-crawl stroke was filmed for a set of five trials. A seven-point model of the arm and hand was then digitised at 25 Hz. Hand velocity, sweepback angle and pitch angle were calculated using the procedures of Schleihauf (1979), Berger et al. J. Biomech. 28 (1995) 125-133 and a newly proposed procedure (Lauder). Statistical comparisons were made between procedures to establish their relative accuracy and reliability throughout the stroke. The mean absolute error in measurement of hand velocity between points on the hand was very small (+/- 0.04 and +/- 0.06 m s(-1) in the x and z directions, respectively). The mean errors in sweepback angle and pitch angle were, respectively, 9.3 degrees and 7.6 degrees (Berger), 10.1 degrees and 8.1 degrees (Schleihauf and 10.7 degrees and 7.0 degrees (Lauder). Agreement between procedures showed the standard error between Schleihauf and Lauder to be the least (Schleihauf and Lauder, 0.4 degrees; Berger and Schleihauf, 1.3 degrees; Berger and Lauder; 1.6 degrees). The use of four points in the reconstruction of the orientation of the hand (Schleihauf and Lauder procedures) was shown to be less sensitive to errors in the digitising procedure. The reconstruction procedure proposed in this study (Lauder). further reduced the sensitivity to digitising error in the reconstruction of sweepback and pitch angles in swimming.

Hand↗
PubMed1999

Hydrodynamics optimization in butterfly swimming: position, drag coefficient and performance.

A kinematic study allowed to define the three most propulsive positions during a butterfly swimming cycle, which were: the end of the external sweep, the end of the internal sweep and the end of thrust. These instantaneous positions were different for the ex-world champion Pankratov when compared to another swimmer. Using manikins and a drag-measuring device, we showed that the end of the internal sweep induced the highest drag values and that Pankratov may reduce energy expenditure by taking up a particular position during the end of the swimming cycle. These results point out the relations between swimming movements, passive drag and swimmers' performance.

Biomechanical Phenomena↗
PubMed2003

Aqueous photolysis of the sunscreen agent octyl-dimethyl-p-aminobenzoic acid. Formation of disinfection byproducts in chlorinated swimming pool water.

The photochemical behavior of the sunscreen agent octyl-dimethyl-p-aminobenzoic acid (ODPABA) was studied in different aqueous solutions and under different conditions. ODPABA photolysis was performed under laboratory conditions using a xenon light source and under natural sunlight conditions in sea, swimming pool as well as in distilled water. The influence of dissolved organic matter (DOM) on the degradation kinetics was also studied in the presence of various concentrations of humic acids (HA). The phototransformation was shown to proceed via pseudo-first-order reaction in all cases and the reaction rates followed the order: distilled water > swimming pool water > seawater, depending mainly on the presence of dissolved organic matter that retarded the photolysis reaction. Kinetic experiments were monitored with HPLC/UV-DAD and the half-lives (t 1/2) varied between 1.6 and 39 h in simulated solar irradiation and between 27 and 39 h in natural sunlight conditions. The product distribution during illumination was strongly dependent on the constitution of the irradiated media. Irradiation of the aqueous ODPABA solutions gave rise to several transformation products that were isolated by means of solid-phase extraction (SPE) and identified using GC-MS techniques. These were formed mainly through dealkylation and hydroxylation reactions and were detected in all aqueous solutions investigated. In the case of swimming pool water some additional byproducts were isolated and were tentatively identified as chlorinated intermediates, formed by the subsequent chlorination of the parent molecule as well as other intermediates.

4-Aminobenzoic Acid↗
PubMed1997

Evidence that adaptation to cold water swim-induced analgesia is a learned response.

Controlling for novelty of the test context, the present experiment determined if adaptation to forced cold water swim stress-induced analgesia is learned through Pavlovian conditioning. Following baseline measurement of pain sensitivity, Group A swam in Context A for 3 min and, 8 h later, sat in Context B for 3 min. The conditions were reversed for Group B. All rats were given a tail-withdrawal test immediately after swimming or sitting in each context. On the first test day, conducted 24 h after the completion of the adaptation phase, all rats swam in Context A for 3 min, and tail-withdrawal latencies were immediately obtained after the swim. On the second test day, 24 h later, all rats swam in Context B, with tail-withdrawal latencies measured immediately thereafter. Both groups showed significantly less analgesia when tested in the adaptation context in which they previously swam than in the other context. These data provide strong evidence that adaptation to stress-induced analgesia is a learned response.

Adaptation, Physiological↗
PubMed2000

Paradoxical effect of imipramine in hyperprolactinemic female rats exposed to the forced swimming test.

This study was designed to investigate the effect of hyperprolactinemia, with high or low estrogen levels, on the response to imipramine in the forced swimming test. Three groups of female rats were studied: (1) ovariectomized controls, with low serum prolactin (PRL) and estrogen levels, (2) ovariectomized, estrogen-treated rats, with high PRL and high estrogen levels, and (3) pituitary-grafted rats, with high PRL and low estrogen levels. The hyperprolactinemic groups did not show significant behavioral changes in the forced swimming test preceded by saline injection. Imipramine decreased the immobility time by 37.5% in ovariectomized controls but not in the pituitary-grafted group, and there was an increment of 48.4% in immobility time following imipramine administration in the estrogen-treated group (p<0.05). This paradoxical response to imipramine was significantly correlated with serum PRL (r = 0.59, p<0.01) but not with estradiol levels. These findings suggest that, at least in female rats submitted to the forced swimming model, PRL may induce reversed behavioral effects in response to imipramine, independently of circulating estrogen levels.

Animals↗
PubMed2000

Antidepressant-like effect of the neurosteroid 3alpha-hydroxy-5alpha-pregnan-20-one in mice forced swim test.

The present study aimed to examine the antidepressant-like effect of the neurosteroid 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha, 5alpha THP) using the forced swim test in mice. Intracerebroventricular (ICV, 1 or 2 microg/mouse) or intraperitoneal (IP, 0.5, 1, or 2 mg/kg) administration of 3alpha, 5alpha THP dose-dependently reduced the duration of immobility in forced swim test without accompanying changes in ambulatory or rearing behaviors in the open-field test. The antidepressant-like effect of 3alpha, 5alpha THP (1 microg/mouse, ICV) was potentiated by prior administration of the GABA(A) receptor agonist, muscimol (0. 5 mg/kg, IP) and blocked by prior administration of GABA(A) receptor antagonist, bicuculline (1 mg/kg, IP). Administration of the agonist at diazepam binding inhibitor receptors, 4'-chlorodiazepam (4'CD, 15 mg/kg, IP) or N,N-di-n-hexyl-2-(4-fluorophenyl)-indol-3-acetamide (FGIN 1-27, 1 or 2 microg/mouse, ICV), the 11beta-hydroxylase inhibitor, metyrapone (150 mg/kg, IP and 1 or 2 microg/mouse, ICV) and the selective serotonin reuptake inhibitor (SSRI), fluoxetine (20 mg/kg, IP), which are known to increase the endogenous level of neurosteroids, also reduced the duration of immobility in forced swim test. The tricyclic antidepressant, imipramine (20 mg/kg, IP), which does not increase the 3alpha, 5alpha THP in the brain, also reduced the immobility time. While the antidepressant-like effect of fluoxetine, which is known to selectively increase the brain content of 3alpha, 5alpha THP, was either blocked partially by bicuculline (1 mg/kg, IP) or potentiated by muscimol (0.5 mg/kg, IP), the antidepressant-like effect of imipramine was not modified by bicuculline. These results demonstrate the antidepressant-like effect of the neurosteroid 3alpha, 5alpha THP, and suggest further evaluation for its development as a new class of antidepressant drug.

Animals↗
PubMed2000

Beta-1 adrenoceptor antagonists potentiate the anticonvulsive effect of swim stress in mice.

To explore the possible involvement of beta adrenoceptor antagonists in the previously observed anticonvulsive effect of swim stress, the mice were, prior to administration of convulsants, pre-treated with propranolol (a non-selective beta adrenoceptor antagonist), betaxolol (a selective beta-1 adrenoreceptor antagonist), or ICI 118,551 (a selective beta-2 adrenoreceptor antagonist). In control unstressed animals, only propranolol [10 mg/kg, intraperitoneally (ip)] produced a significant change. It enhanced the threshold dose of picrotoxin producing tonic hindlimb extension. However, in swim-stressed animals, propranolol enhanced doses of picrotoxin producing tonic hindlimb extension and death, while betaxolol (20 mg/kg, i.p.) enhanced doses of picrotoxin producing running/bouncing clonus, tonic hindlimb extension and death. Pre-treatment with ICI 118,551 (4 mg/kg, i.p.) failed to affect doses of picrotoxin producing convulsions and death. The results demonstrate that blockade of beta-1 adrenoceptors potentiates the anticonvulsant effect of swim stress against convulsions produced by picrotoxin, a noncompetitive GABA(A) receptor antagonist.

Adrenergic beta-1 Receptor Antagonists↗
PubMedDate not supplied

Enhanced corticosterone release after a modified forced swim test in Fawn hooded rats is independent of rearing experience.

Recent findings have demonstrated that Fawn hooded (FH/Har) rats exhibit enhanced plasma corticosterone (CORT) responses compared to Wistar rats after exposure to an open field, whereas this effect was not influenced by early social experience. In contrast, it was found that behavior in a modified version of the Porsolt Forced Swim Test (Porsolt FST) was affected by both strain and social experience. An important part of this study included modifications of the Porsolt FST that allowed separation of multiple behavioral endpoints. The present experiment was conducted to determine if FH/Har rats also exhibit enhanced CORT responses after exposure to the modified forced swim test, and whether CORT levels might predict the behavioral response in this context. After the initial exposure in the modified forced swim test FH/Har rats had higher CORT levels than Wistar rats, but this difference was not affected by isolation rearing. However, CORT levels were not correlated with the main behavioral measures assayed in this test. Nonetheless, the data confirm that FH/Har rats have altered HPA axis responses to stressors.

Animals↗
PubMed2002

The effect of Morinda officinalis How, a Chinese traditional medicinal plant, on the DRL 72-s schedule in rats and the forced swimming test in mice.

The present study observed the antidepressant-like action of the medicinal plant Morinda officinalis in the differential reinforcement of low rate 72-s (DRL 72-s) schedule, a behavioral screen selective and sensitive to antidepressant drugs, and the forced swimming test, a well-known animal model of depression. In the DRL 72-s schedule in rats, the plant extract (25-50 mg/kg), similar to clinically effective antidepressant drug desipramine (5-10 mg/kg), significantly reduced response rate and efficiency ratio while at the same time increasing reinforcement rate. In the forced swimming test in mice, the plant extract (50 mg/kg), like the effect of desipramine (20 mg/kg), also elicited a significant reduction in the duration of immobility. A tendency to this phenomenon could be seen at the dose of 100 mg/kg. Meanwhile, the plant extract, in the effective doses for the forced swimming test, had no effects on spontaneous motor activity in mice. These findings provide further support for the conclusion that M. officinalis extract possesses the antidepressant effect.

Animals↗
PubMed1997

Sex and genotype determine the selective activation of neurochemically-distinct mechanisms of swim stress-induced analgesia.

A growing literature documents the important influence of organismic factors such as sex and genotype on pain sensitivity and pain modulation. We recently determined that 3-min forced swims in 15 degrees C water produce non-opioid (i.e., naloxone-insensitive) analgesia in outbred Swiss-Webster mice of both sexes; this form of stress-induced analgesia (SIA) is significantly attenuated by the N-methyl-D-aspartate (NMDA) antagonist, dizocilpine (MK-801) in males, but not females. A pilot study designed to confirm the non-opioid and (in male mice) NMDAergic nature of 15 degrees C swim SIA in the C57BL/6J and DBA/2J inbred strains used widely in gene mapping was conducted, using the hot-plate (54 degrees C) assay of nociception. In female mice of both strains, 15 degrees C swim SIA was insensitive to antagonism by either naloxone (10 mg/kg, i.p.) or dizocilpine (0.1 mg/kg. i.p.). In male C57BL/ 6J mice, the observed SIA was naloxone-insensitive, but was attenuated by dizocilpine. This pattern of results is virtually identical to that obtained using Swiss-Webster mice in this and previous studies. However, male DBA/2J mice displayed SIA that was significantly attenuated by naloxone, but insensitive to dizocilpine antagonism. These findings support the hypothesis that genetic factors and sex, in addition to stressor parameters, can determine the selective recruitment of alternative central mechanisms of pain inhibition.

Analgesia↗
PubMed1981

Effect of swimming on forced expiration and sputum clearance in cystic fibrosis.

Ten children with cystic fibrosis participated in swimming training over 7 weeks. Ventilatory status, assessed by spirometry, had improved significantly after the course. 10 weeks after the end of the training most measurements had returned to their preswimming levels. In the majority of the children sputum production on swimming days was higher than on nonswimming days. Regular swimming can assist in mucus clearance and improve ventilatory function in children with cystic fibrosis.

Adolescent↗
PubMedDate not supplied

Mysids and trace metals: disruption of swimming as a behavioural indicator of environmental contamination.

Mysids are used frequently in standard laboratory studies of acute exposure to chemical contaminants. Their value for sub-lethal measures of biological response to predict the potential effects of environmental toxicants, however, has yet to be determined. In estuaries, mysids maintain their optimum position independent of the forces of river flow and tides; therefore, any disruption of swimming behaviour will have significant implications for their survival and position maintenance. In the present study, the effects of cadmium on the swimming behaviour of the hyperbenthic estuarine mysid Neomysis integer, which occupies the heads of European estuaries, are presented. Following 7 day exposure to cadmium, swimming behaviour (ability and orientation) was disrupted at 0.5 microgram Cd(aq)2+ l-1, a significantly lower cadmium concentration than that causing mortality (7 day LC50 of 2.58 micrograms Cd(aq)2+ l-1). The results of this investigation highlight the advantages of behavioural toxicity tests for predicting the influence of pollutants and support the use of mysids for estuarine monitoring.

Animals↗
PubMed1998

The effects of social isolation on the forced swim test in Fawn hooded and Wistar rats.

Although the forced swim test (FST) has long been used as a preclinical screen of antidepressant efficacy, locomotor stimulants are known to produce confounding effects using the traditional dependent measure in this test: immobility. It has recently been suggested that measurement of struggling behavior may be a better index of antidepressant activity. The present experiments examined behavior in the forced swim test in two potential animal models of depression: the Fawn hooded rat, and the isolation-reared rat. No evidence was found to support these assertions, indeed immobility was decreased in Fawn hooded compared to Wistar rats, however this appeared to be caused by increased struggling behavior in Fawn hooded socials and increased swimming in Fawn hooded isolates. Although these differential results are highly suggestive of different underlying causes of decreased immobility in Fawn hooded rats depending on rearing conditions, the data suggests that the underlying psychological functions assumed to be represented by behavior assessed in this paradigm may not be adequately discriminated.

Animals↗
PubMed2001

The antidepressant activity of inositol in the forced swim test involves 5-HT(2) receptors.

The effect of inositol as an antidepressant was previously demonstrated in both animal models of depression-like behavior and in clinical trials. Unlike most antidepressant drugs, inositol does not have a clear target in the synapse and was not demonstrated to alter monoamine levels in the brain. The present study attempted to draw a psychopharmacological profile of inositol's behavioral effects by exploring the interactions between the drug and specific receptor agonists and antagonists in the forced swim test. Rats received inositol treatment (or control) in combination with the serotonergic metabolism inhibitor PCPA or with the noradrenergic neurotoxin DSP-4. Results indicated that PCPA but not DSP-4 abolished the ability of inositol to cause a reduction in immobility time in the forced swim test. In mice, the specific 5-HT(2A)/5-HT(2C) antagonist ritanserin, but not the 5-HT(1A)/5-HT(1B)/beta adrenergic antagonist pindolol, abolished inositol's effect in the forced swim test. The 5-HT(2A)/5-HT(2C) agonist DOI and the 5-HT(1A) agonist 8-OH-DPAT did not have any significant effects on inositol's activity. The present data indicates that the antidepressant effect of inositol may involve 5-HT(2) receptors. It is thus possible that the effects of reuptake antidepressant drugs and the effects of inositol may have a common final pathway.

Animals↗
PubMed1998

Nonassociative learning processes affecting swimming probability in the seaslug Tritonia diomedea: habituation, sensitization and inhibition.

The role of nonassociative learning processes in determining whether or not a chemical stimulus will elicit the Tritonia diomedea swimming response was examined in a variety of conditioning experiments. Iterative presentation of a chemical stimulus resulted in a reduced swimming probability (SP). By the criteria of Thompson and Spencer (Thompson RF, Spencer WA. Psychol. Rev. 1966;73:16-43) and others, this iterative reduction of SP was concluded to be the result of habituation. Site-specificity and a below zero effect implicated sensory pathways in habituation memory storage. The iterative reduction in SP was reversible, confirming that a sensitization-like process can also influence SP. It was further concluded that a short-term decrement in swimming cycle number was most likely due to a constraint in the effector pathway. Experience with a tactile stimulus had a long-lasting decremental effect on SP. This heterostimic reduction of SP was amplified in a multistimic paradigm that included both chemical and tactile stimuli during training. The chemical stimuli alone did not alter SP in this experiment. Multistimic reduction lasted for a week and was reversed temporarily by an excitatory chemical stimulus. The long-lasting reduction of SP by tactile stimulation appears to be the result of a novel nonassociative inhibitory process, which was distinguished from other learning processes by its duration and specificity. A total of three distinct learning processes are postulated to account for the role of simple types of experience in determining SP in Tritonia: habituation, sensitization, and nonassociative inhibition.

Animals↗
PubMed2000

Effects of pre-acclimation to aluminium on the physiology and swimming behaviour of juvenile rainbow trout (Oncorhynchus mykiss) during a pulsed exposure.

Anthropogenic acidification of the freshwater environment causes aluminium to be mobilised into the aquatic environment. When pH falls below 5.5, exposure to aluminium concentrations as low as 12.5 microg.l(-1) can cause serious physiological disturbances in freshwater fish. However, under constant laboratory exposures fish can acclimate and recover physiological status within 5-30 days. In reality, fish in the wild are likely to experience chronic sub-lethal exposure, with occasional elevations (pulses) to much higher levels. The experiment described here investigated the effects of an environmentally realistic, 4-day pulse exposure to a high level of aluminium (36 microg.l(-1)) in two groups of juvenile rainbow trout. One group was exposed to a lower level of aluminium (24 microg.l(-1)) for 16 days before and 10 days after the pulse ('aluminium-acclimated' fish). A second group was exposed to pH 5.2 alone for 16 days before and 10 days after the pulse ('aluminium-naïve' fish). A third group exposed to pH 5.2 alone for 30 days (no aluminium added) acted as controls. Triplicate groups of 24 juvenile rainbow trout (2.3-16.7 g) were randomly allocated to one of these three treatments. Swimming behaviour was monitored throughout and samples were taken on days 14, 20, 22, 26 and 30 for assessment of physiological status. No treatment effects were recorded in the control group (pH 5.2 alone). Fish in the 'aluminium-acclimated' treatment became hypo-active upon initiation of the exposure to 24 microg.l(-1) aluminium, but recovered after just 4 days of this exposure. Subsequent challenge on day 16 with the 36 microg.l(-1) aluminium 'pulse' caused these fish to became hypo-active again, but they recovered normal swimming behaviour whilst still subject to the 4-day pulse. The 'aluminium-naïve' fish also became hypo-active during the pulse exposure (36 microg.l(-1) aluminium). However, they did not exhibit any recovery of swimming behaviour, either during the pulse, or even 6 days after the cessation of the pulse, despite a rapid depuration of gill aluminium load (within 2 days of the pulse finishing). Mortality was low in the aluminium-acclimated fish (4%) and significantly higher in the aluminium-naïve fish (26%). Haematological disturbances were most extreme in the aluminium-naïve fish and had not recovered to control levels 6 days after the end of the pulse. This study provides new evidence, using behavioural responses, that previous exposure to low levels of aluminium may be an important factor abating the impact of aluminium on fish in the natural environment.

Adaptation, Physiological↗
PubMed2002

Effects of altered gravity on the swimming behaviour of fish.

Humans taking part in parabolic aircraft flights (PAFs) may suffer from space motion sickness-phenomena (SMS, a kinetosis). It has been argued that SMS during PAFs might not be based on microgravity alone but rather on changing accelerations from 0 g to 2 g. We test here the hypothesis that PAF-induced kinetosis is based on asymmetric statoliths (i.e., differently weighed statoliths on the right and the left side of the head), with asymmetric inputs to the brain being disclosed at microgravity. Since fish frequently reveal kinetotic behaviour during PAFs (especially so-called spinning movements and looping responses), we investigated (1) whether or not kinetotically swimming fish at microgravity would have a pronounced inner ear otolith asymmetry and (2) whether or not slow translational and continuously changing linear (vertical) acceleration on ground induced kinetosis. These latter accelerations were applied using a specially developed parabel-animal-container (PAC) to stimulate the cupular organs. The results suggest that the fish tested on ground can counter changing accelerations successfully without revealing kinetotic swimming patterns. Kinetosis could only be induced by PAFs. This finding suggests that it is indeed microgravity rather than changing accelerations, which induces kinetosis. Moreover, we demonstrate that fish swimming kinetotically during PAFs correlates with a higher otolith asymmetry in comparison to normally behaving animals in PAFs.

Acceleration↗