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PubMed1998

Swimming stress that causes hyperglycemia increases in vivo release of noradrenaline, but not acetylcholine, from the hypothalamus of conscious rats.

The effects of acute swimming stress (10 min) on noradrenaline release from the medial basal hypothalamus (MBH; consisting of the ventromedial and dorsomedial hypothalamus) and acetylcholine release from the lateral hypothalamic area (LHA) were investigated in freely moving rats by using in vivo microdialysis techniques. Serum glucose, noradrenaline and adrenaline concentrations were also determined. Acute swimming stress produced significant hyperglycemia, with increases in serum noradrenaline and adrenaline concentrations. The release of noradrenaline from the MBH was significantly stimulated during the swimming stress. On the other hand, the swimming stress has no significant effect on the release of acetylcholine from the LHA. These findings support the idea that hypothalamic noradrenergic neurons play an important role in the sympathoadrenal hyperglycemic response to stressful stimuli. Moreover, it is suggested that hypothalamic cholinergic neurons are not involved in the responses of serum glucose, noradrenaline and adrenaline concentrations to swimming stress.

Acetylcholine↗

PubMed2001

Paradoxical effects of chronic corticosterone on forced swim behaviours in aged male and female rats.

The effects of chronically administered corticosterone on forced swim test and open field test behaviours were explored in aged male and female rats. Though corticosterone has typically been associated with depressive behaviours, recent data have suggested a putative antidepressive effect of corticosterone. The current study used the forced swim test as a model of antidepressant efficacy in order to explore this. Aged male and female rats received either corticosterone (20 mg/kg) or the vehicle for 10 days before testing in the forced swim test, then for an additional 3 days before testing in the open field test. On day 11, each animal was individually tested on the duration of swimming, immobile, and struggling behaviours, and on day 14, for the display of rearing and line crossing behaviours. Results revealed that corticosterone significantly increased swimming and decreased immobility behaviour in females, but failed to do so in males. Additionally, there was a main effect of corticosterone on struggling behaviour such that it decreased it in males. There were no effects of corticosterone or sex on open field test behaviours, suggesting that the present findings are not accounted for by a general effect of corticosterone on motor behaviour. Overall, the data suggest that chronically administered corticosterone possesses effects that are sex-specific, and that it may exert mildly antidepressive effects in females, but the opposite effects in males. These data are consistent with emerging evidence that corticosterone may play a paradoxical antidepressive effect.

Aging↗

PubMed1975

Effects of swimming on dystrophic Syrian hamster heart.

Morphological and histopathological heart changes were determined for sixteen dystrophic Syrian hamsters (B10 14.6 strain) and sixteen normal hamsters. Eight animals were randomly assigned to each of the following groups: dystrophic swim (DYS-SWM), dystrophic sedentary (DSY-SED), normal swim (NOR-SWM), and normal sedentary (NOR-SED). The daily swimming program consisted of an initial 30-minute swim which was gradually extended to 60 minutes by the end of eight weeks. Weights up to 3% body weight were attached during swimming to increase the work load. Sedentary animals received no experimental treatment. Four animals in each group were sacrificed at 4 and 8 weeks after the initiation of treatments. In comparison with the two groups of sedentary animals, the NOR-SWM group had a greater heart weight/body weight ratio at both 4 and 8 weeks (P less than .05), while the DYS-SWM group had an increased ratio only at 8 weeks (P less than .05). Subjective histopathological evaluation of heart lesions showed that the DYS-SED group had many large areas of inflammatory reaction with infrequent diffuse areas of calcification. In contrast, the DYS-SWM group had fewer and smaller areas of inflammatory reaction with moderate amounts of calcification.

Animals↗

PubMed2004

Impacts of beach closures on perceptions of swimming-related health risk in Orange County, California.

Following a major beach closure due to bacterial contamination, a survey of beachgoers was conducted in Huntington Beach, California in 1999 to assess perceived health risk from swimming. Responses were compared to those of beachgoers at the unaffected Laguna Main Beach. No significant differences were found in risk perception. Respondents were aware of the closures (83%), yet the majority (83%) felt the water was safe for swimming. Proximity of residence to the beach was strongly associated with closure awareness (Spearman's rho=0.427, p<0.0001). Although 83% of respondents felt that water quality was important in deciding to go to the beach, only 25% of respondents who did not plan to swim cited pollution or contamination as a reason not to swim. Most respondents (70%) trusted local health agency officials' decisions about when to open/close beaches. Surveyed beach visitors were likely to bathe (84%) and were not highly concerned with swimming-related health risks.

Adult↗

PubMedDate not supplied

Failure of neonatal clomipramine treatment to alter forced swim immobility: chronic treadmill or activity-wheel running and imipramine.

We examined whether chronic running on a treadmill or activity wheel would attenuate the increased swim immobility that has been reported after neonatal clomipramine (CLI) treatment. Male Sprague-Dawley pups (N = 60) were injected with the monoamine reuptake inhibitor clomipramine hydrochloride (40 mg/kg per day i.p.) from 8 to 21 days of age. Another group (N = 12) received saline vehicle. At age 4 weeks, the CLI pups were randomly assigned to experimental conditions: (1) sedentary; (2) 24-h access to an activity wheel; (3) sedentary that received the antidepressant drug imipramine hydrochloride (10 mg/kg twice daily) during the last 10 days of the experiment; (4) activity wheel + imipramine; (5) treadmill running (30 m/min for 1 h at 0 degrees incline, 6 days/week). At age 16 weeks, rats underwent the Porsolt swim test 48 h after the last imipramine injection and/or the last exercise session. The increase in swim immobility among CLI-treated rats was small (one quarter of SD) and not statistically significant (p>0.10). The results are not consistent with our previous finding of antidepressant-like effects of activity-wheel running based on brain noradrenergic adaptations and enhanced male copulatory performance after neonatal CLI treatment. The lack of change in swim performance after clomipramine questions the generalizability of the CLI model of depression and the validity of the forced swim test as a behavioral measure of depression when it is used after neonatal CLI injection or chronic activity-wheel running.

Adrenergic Uptake Inhibitors↗

PubMed1982

Swimming in Aplysia brasiliana: analysis of behavior and neuronal pathways.

Swimming of Aplysia brasiliana was analyzed using time-lapse video and computer graphics techniques to quantify the cyclical movements of different regions of the parapodia. Both the speed of swimming and the period of oscillation are temperature dependent, whereas the metachronal offset is not. The parapodial arterial supply is described; ligation of parapodial arteries does not affect the parapodial motions. Peripheral and central lesions indicated that (1) the anterior parapodial nerve plays the major role in parapodial flapping, (2) a separate neuronal oscillator resides in each pedal ganglion, (3) bilateral coordination is mediated via the pedal commissure, and (4) the swimming "command" pathway is the cerebro-pedal connective. During regular parapodial flapping the speed of level midwater swimming is constant throughout the cycle, suggesting that swimming is not produced by jet propulsion. An alternative propulsion model is advanced.

Animals↗

PubMed1997

Sex differences in the effects of gonadectomy and acute swim stress on GABAA receptor binding in mouse forebrain membranes.

Gonadectomy of male mice resulted in a significant increase in GABAA receptor binding in forebrain membranes at GABA concentrations of 100-1000 nM, whereas gonadectomy of female mice resulted in no significant change in such binding. Acute swim stress (3 min swim at 32 degrees C) in gonadectomised female mice resulted in a significant increase in GABAA receptor binding in forebrain membranes at GABA concentrations of 400-1000 nM and in the plasma levels of corticosterone, whereas this stress produced no significant change in such binding or steroid levels in gonadectomised male mice. The surgical stress of sham gonadectomy produced significant increases in GABAA receptor binding in forebrain membranes at GABA concentrations of 100-1000 nM in both sexes, such that the acute swim stress induced increase in GABAA receptor binding in unoperated females is not observed. Hormone replacement studies in swim stressed gonadectomised females indicate that intraperitoneal injection of oestrogen (beta-oestradiol, 10 micrograms) or progesterone (6 alpha-methyl-17 alpha-hydroxy-progesterone acetate, 1 mg) significantly decreased GABAA receptor binding in forebrain membranes at GABA concentrations of 100-1000 nM compared to swim stressed, gonadectomised females injected with the sesame oil vehicle. The injection of a combination of oestrogen (1 microgram) and progesterone (0.1 mg) produced a greater reduction in GABAA receptor binding than the injection of either steroid hormone alone. These results indicate that, in addition to neurosteroids and corticosteroids, gonadal steroids contribute to the modulation of GABAA receptor binding in the brains of male and female mice.

Animals↗

PubMed1999

The physiology and biomechanics of competitive swimming.

Fast swimming, either in the pool, in open water swimming, or in water polo and synchronized swimming, requires maximizing the efficiencies with which the human body can move through a liquid medium. A multitude of factors can affect the ability to swim fast as well as the final outcome. Physiology and biomechanics are the present tools used by sports scientists to determine which factors are important to fast swimming and, subsequently, to determine how the swimmer may maximize these factors to improve performance.

Biomechanical Phenomena↗

PubMed2002

Release patterns of excitatory and inhibitory amino acids within the hypothalamic supraoptic nucleus in response to direct nitric oxide administration during forced swimming in rats.

The effect of direct intrahypothalamic nitric oxide (NO) administration on the release of selected amino acids in the hypothalamic supraoptic nucleus (SON) with and without concomitant forced swimming was investigated. Adult male Wistar rats were chronically fitted with U-shaped microdialysis probes in the SON and forced to swim for 10-min in 20-degree C warm water. Thirty-min microdialysis samples were collected before, during and after the forced swimming period while NO was administered into the SON via microdialysis. The results show that NO administration in combination with forced swimming affects the release of aspartate, glutamate, taurine, and gamma aminobutyric acid (GABA) in different patterns. Whereas the release of the excitatory amino acids aspartate and glutamate was triggered only during NO administration and forced swimming, the inhibitory amino acids GABA and taurine were found in the extracellular fluid in increased concentrations also after the treatment. These data indicate that NO administration differently affects the release of excitatory and inhibitory amino acids within the SON. Thus, SON neurons which contain high concentrations of neuronal NO synthase, might contribute to the regulation of their own secretory activity by releasing NO that controls the orchestrated release of excitatory and inhibitory amino acids from axon terminals of afferences and interneurons as well as release from glial cells.

Animals↗

PubMed1997

Motor activity and quantitative autoradiographic analysis of muscarinic receptors in the brain of rats subjected to the forced swimming test.

A cholinergic dysfunction has been involved in the neurobiological mechanisms of stress and depression. In the present study, we determined the autoradiographic distribution of muscarinic cholinergic receptors in the brain of rats subjected to the forced swimming test for 15 days. Motor activity was automatically analyzed daily before swimming. In the forced swimming test group, both total horizontal activity and ambulatory movements exhibited a significant decrease, when the data from 1st and 15th day were compared. Neither the affinity of [3H]-quinuclidinyl benzilate nor the maximal number of receptors were affected by the forced swimming test in the caudate-putamen, cortex, and hippocampus. The distribution of [3H]-quinuclidinyl benzilate binding sites did not show significant differences in the 30 analyzed areas. Further analysis of muscarinic receptor subtypes after forced swimming test would be necessary to discard any cholinergic involvement.

Animals↗

PubMedDate not supplied

Effects of prenatal exposure to deltamethrin on forced swimming behavior, motor activity, and striatal dopamine levels in male and female rats.

The effects of prenatal exposure of rat pups to 0.08 mg/kg deltamethrin (DTM) on physical, reflex and behavioral developmental parameters, on forced swimming and open-field behaviors, and on striatal monoamine levels at 60 days of age were observed. Maternal and offspring body weight, physical and reflex development were unaffected by the exposure to the pesticide. At 21 days of age, open-field locomotion frequency and immobility duration of male and female offspring were not different between control and exposed animals. However, male rearing frequency was increased in experimental animals. A decreased immobility latency to float and in general activity after the swimming test in male offspring was observed at adult age; no interference was detected in the float duration during the swimming test. In addition, these animals presented higher striatal 3,4-dihydroxyphenylacetic acid (DOPAC) levels without modification in dopamine (DA) levels and an increased DOPAC/DA ratio. These data indicate a higher activity of the dopaminergic system in these animals. Noradrenaline (NA) levels were increased, while MHPG levels were not detectable in the system studied. Serotonin (5-HT) and 5-hydroxyindolacetic acid (5-HIAA) levels, as well as the homovanillic acid (HVA)/DA ratio, were not modified by the exposure to the pesticide. No changes were observed in swimming and open-field behaviors nor were there any changes in striatal monoamines or their metabolites in the female experimental group. In relation to the pesticide formula, the present data showing that prenatal exposure to DTM alters latency to float and the activity of striatal dopaminergic system might reflect a persistent effect of the pesticide on animal motor activity, mainly in males. On the other hand, the decrease in general activity observed in experimental male rats suggests higher levels of emotionality induced by previous exposure to the swimming behavior test in relation to control animals. Data gathered in the present study may be important for the assessment of the safety of pyrethroid insecticides.

Administration, Oral↗

PubMed2002

The neuropeptide Y (NPY) Y1 receptor subtype mediates NPY-induced antidepressant-like activity in the mouse forced swimming test.

The present study was undertaken to investigate the possible antidepressant-like effects of neuropeptide Y (NPY) in the mouse forced swimming test, an animal model widely used for the screening of potential antidepressant drugs. In addition, experiments were performed, using agonists and selective antagonists, to assess the potential role of NPY Y(1) and Y(2) receptor subtypes in this model. Complementary studies were performed in an open field apparatus to rule out any changes in locomotor activity that might have interfered with the interpretation of data from the mouse forced swimming test. Intracerebroventricular injections (0.03 nmole-3 nmole) of NPY, [Leu(31)Pro(34)]PYY (Y(1) agonist), NPY(13-36) (Y(2) agonist), BIBP3226, BIBO3304 (Y(1) antagonists) and BIIE0246 (Y(2) antagonist) were performed 30 min prior to testing in the mouse forced swimming test and open field. NPY administration significantly reduced immobility time in a dose dependent manner (p <.01 vs. control group), as did [Leu(31)Pro(34)]PYY (p <.01 vs. control group) and BIIE0246 (p <.05 vs. control group). In contrast, BIBO3304, BIBP3226 and NPY(13-36) did not display any activity at the doses tested. However, pretreatment with BIBO3304 or BIBP3226 significantly blocked the anti-immobility effects of NPY. Data from the open field demonstrated that BIIE0246 increased horizontal ambulation at the dose found to be active in the forced swimming test. Taken together, our results demonstrate that NPY displays antidepressant-like activity in the mouse forced swimming test, and suggest that this activity is mediated by the NPY Y(1) receptor subtype.

Animals↗

PubMed2002

Acute swimming stress induces changes in noradrenergic mechanisms in order to maintain the response pattern of the rat vas deferens to norepinephrine.

This study investigated mechanisms involved in the maintenance of the functional response pattern of the postjunctional alpha(1)-adrenoceptor in vas deferens isolated from rats submitted to acute swimming stress. The plasma corticosterone levels increased approximately three times after the swimming stress in the nontreated rats as well as after swimming stress in the rats pretreated with desipramine (DMI), yohimbine (YO), or DMI with YO. No alteration was detected in the sensitivity to norepinephrine (NE) in the vasa deferentia from the stressed rats or stressed rats treated with DMI or DMI with YO, in relation to their respective control. However, when the vasa deferentia were previously incubated with DMI, a reduction in sensitivity to NE in organs from stressed rats was observed. Vasa deferentia excised from rats pretreated with YO before the swimming stress showed an increase in postjunctional alpha(1)-response that was abolished by prazosin (PZ). Thus, the neuronal uptake, the prejunctional alpha(2)-adrenoceptors (mediating prejunctional inhibition), the occupancy and functional response of the postjunctional alpha(1)-adrenoceptors, and the emotional stress component were very important for the determination of the noradrenergic response pattern in vas deferens from rats submitted to acute swimming stress.

Animals↗

PubMed2004

Red muscle recruitment during steady swimming correlates with rostral-caudal patterns of power production in trout.

Rainbow trout (Oncorhynchus mykiss) and brook trout (or charr, Salvelinus fontinalis) display different rostral-caudal patterns of power production by the red or aerobic muscle during steady swimming. The anterior muscle of rainbow trout produces much less power for swimming than the posterior, while in brook trout there is no variation in power output. To determine if red muscle recruitment is associated with anterior-posterior patterns of power production, electromyography (EMG) was used to record red muscle activity at three body positions across a range of swimming speeds in fish of each species. The initial recruitment of the anterior red muscle in swimming rainbow trout was predicted to lag behind, i.e. occur at higher speeds, that of the posterior due to the variation in power production, but no variation in recruitment was expected for brook trout. Burst of red muscle EMG activity occurring with each tailbeat was analyzed for frequency (tailbeat frequency), duty cycle (DC) (duration of burst relative to the period of the tailbeat) and burst intensity (BI) (magnitude of the measured EMG activity). Brook trout swam with higher tailbeat frequencies and longer values of DC than rainbow trout. Both species showed a pattern of longitudinal variation in DC, with longer DC values in the anterior red muscle. BI also differed significantly along the length of rainbow trout but not brook trout. In the former, BI of anterior muscle was significantly less than the posterior at lower steady swimming speeds. The EMG data suggest that power production and muscle recruitment are related. In rainbow trout, where there is longitudinal variation in muscle power output, there are also significant rostral-caudal differences in red muscle recruitment.

Analysis of Variance↗

PubMed1998

Relative distribution of blood flow in rats during surface and submerged swimming.

The relative distribution of blood flow was investigated in conscious rats with a radiological imaging technique that utilizes technetium-99m ethyl cysteinate dimer (99mTc-ECD). The objective of the study was to determine the effects of locomotory activity on the distribution of blood flow during a dive response. We compared the relative distribution of systemic flow in rats at rest, surface swimming and during periods of voluntarily initiated underwater swimming. The pattern of blood flow differed considerably between the three groups of rats. In resting controls, blood flow was widely distributed throughout the whole body with the thoraco-abdominal region receiving the largest fraction of cardiac output. During surface swimming blood shifted towards the exercising limbs, while during underwater swimming systemic blood flow was largely restricted to the head and thorax. However, the active front and hind limbs were not rendered totally ischemic. This suggests that the demands of exercising skeletal muscle partially over-ride the peripheral vasoconstriction during asphyxic diving in conscious rats. Furthermore, relative blood flow to the head increased during underwater swimming, which supports the view that there is a preferential maintenance of blood flow to the brain.

Abdomen↗

PubMed1993

Grommets, swimming and otorrhoea--a review.

Ever since Armstrong reintroduced the concept of grommet insertion parents have been asking 'may my child swim?', yet there is still no consensus as to the correct answer. This paper reviews the work that has been done on this subject in the last 25 years. A review of the rates of otorrhoea following grommet insertion, irrespective of swimming, shows a variation from 12 to 64 per cent. Evidence suggests that pressures of 12-23 cm H2O are needed to push water through a grommet and that it is unlikely that water will enter the middle ear during surface swimming. Only bath water seems to cause significant inflammatory changes to middle ear mucosa. Not a single paper comparing swimmers with non-swimmers shows an increased rate of otorrhoea in those patients who swam; to the contrary, rates of otorrhoea were repeatedly higher in those patients who did not swim. The evidence suggests that swimming without ear protection can be safely permitted for children with grommets.

Adolescent↗

PubMed1985

Cholinergic receptor blockade in the rat impairs locale but not taxon strategies for place navigation in a swimming pool.

Normal rats and rats drugged with atropine sulfate, a cholinergic muscarinic blocker, were evaluated in the Morris water task for their use of spatial navigation strategies. Atropine-treated rats were impaired on a place response of swimming to a platform hidden in a pool filled with opaque water. With extended training, they did learn the place response, though not with control precision, as shown by better than chance heading angles upon swim initiation, searches in the old location for a platform that had been moved, and by correct swims from novel starting locations. Acquisition could not be accounted for by habituation to the drug. In contrast with the acquisition deficit, pretrained rats were relatively unimpaired by the drug. In separate experiments, the strategies used by the drugged animals were examined. Atropine-treated rats were not impaired in acquisition or retention of a cue task, swimming to a visible platform, or a position response task, turning left to locate a platform, but both control and atropine-treated rats were unable to reverse position responses. Possibly, atropine-treated rats can use cue and position response strategies in part or in combination to acquire a place response. Atropine-treated rats were unable to acquire a place learning set, which involved swimming to a new location each day, a response that is eventually performed by normal rats in approximately one trial. They also were unable to perform a learning-set response, which they had acquired when undrugged. Insofar as the impairments following atropine are characteristic of a deficit in the use of a locale strategy, that is, making rapid use of relational properties of distal cues, whereas their successes are characteristic of the use of taxon strategies, that is, cue or position responses, the results suggest that locale systems of navigation are more importantly dependent on cholinergic brain mechanisms than taxon strategies. The resistance of preacquired place responses to atropine may suggest that normally rats acquire place responses by using a locale strategy but effect rehearsed responses by using taxon strategies. Finally, characteristic differences in acquisition, retention, and reversal of atropine-treated and control rats using different navigational strategies suggest new possibilities for interpreting various performance features displayed by animals after other types of treatment.

Animals↗

PubMed1997

Tinea pedis outbreak in swimming pools in Japan.

This study was conducted to show a higher prevalence of interdigital tinea pedis in athletes by comparing athletes and non-athletes, and to examine swimming pools as a route of infection. The subjects were 282 athletes, 137 non-athletes, and 140 students enrolled in a swimming class at the University of Tsukuba. This study included the taking of cotton-swab samples from the interdigital skin surfaces of both feet and cultures, microscopical examinations of scales collected from subjects with lesions, and questionnaires. There was a significant difference between athletes and non-athletes in the prevalence of the relevant pathogens, and a higher risk of infection was shown in athletes. The study also found that 63.6% of the swimming class students were carriers, and that 85.0% of their dermatophytes were Trichophyton mentagrophytes. In addition, dermatophytes were also isolated from the floors of the swimming pool and the public baths. The results of these controlled studies suggested that there was a significant risk of dermatophytosis in both athletes and non-athletes using the swimming pool.

Adult↗