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PubMed1995

Chronic forced swim stress of rats increases frontal cortical 5-HT2 receptors and the wet-dog shakes they mediate, but not frontal cortical beta-adrenoceptors.

We studied the effects of chronic forced swim stress on 5-HT2 receptors and beta-adrenoceptors in the rat frontal cortex. The number of 5-HT2 receptors was increased immediately after the last chronic stress, but not after an acute stress. In vivo, the number of wet-dog shakes induced by a 5-HT2 receptor agonist, (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), was increased 24 h after the last chronic stress. However, the concentrations of 5-HT and 5-hydroxyindole acetic acid (5-HIAA), measured by high pressure liquid chromatography (HPLC), were not altered by this stress. Binding sites for [3H]CGP-12177, i.e., beta-adrenoceptor sites, were unchanged after both the acute and the chronic stress. These results suggest that, in the rat, the chronic forced swim stress increases the number of frontal cortical 5-HT2 receptors and the number of wet-dog shakes mediated by these receptors, while the number of frontal cortical beta-adrenoceptors is not increased by this treatment.

Amphetamines↗
PubMed1996

Nitric oxide modulates retention of immobility in the forced swimming test in rats.

Although originally developed as a possible screen for antidepressants, the Porsolt forced swimming test has more recently been extensively used as a model for studying the involvement of the endocrine system in the acquisition and retention of behavioural responses. In previous studies we have shown that while adrenalectomised rats acquire the immobile response normally, they are unable to retain it on retest next day. In the present study we show that retention of the immobile response in the Porsolt swim test is impaired in intact rats given the nitric oxide (NO) inhibitor L-N-arginine methyl ester (L-NAME), in a dose- and time-dependent manner. At a dose of 50 mg/kg levels of immobility are similar to those in adrenalectomised animals, an effect reversed by the simultaneous administration of L-arginine (50 mg/kg). L-Arginine also reverses the behavioural effect of adrenalectomy, and L-NAME blocks the ability of dexamethasone or the kappa-selective opioid ketocyclazocine to reverse the effect of adrenalectomy on retention of the immobile response. We conclude that the kappa-opioid and glucocorticoid mediated pathways previously shown to independently facilitate retention are mediated by nitric oxide.

Animals↗
PubMed1996

Antisense to the glucocorticoid receptor in hippocampal dentate gyrus reduces immobility in forced swim test.

Immobility time of rats in the forced swim test was reduced after bilateral infusion of an 18-mer antisense phosphorothioate oligodeoxynucleotide targeted to the glucocorticoid receptor mRNA into the dentate gyrus of the hippocampus. Vehicle-, sense- and scrambled sequence-treated animals spent significantly more time immobile than antisense-treated animals during the initial test. Immunolabeling of the glucocorticoid receptor in brain sections demonstrated a reduced expression of glucocorticoid receptor proteins in antisense-treated dentate gyrus compared to the contralateral sense-treated dentate gyrus or contralateral scrambled sequence-treated dentate gyrus. During the initial test the time spent on immobility was also reduced when rats were treated with the glucocorticoid receptor antagonist RU38486 (17 beta-hydroxy-11 beta-(4-dimethylamino-phenyl)17 alpha-(1-propnyl)estra-4,9-diene-3-one)) 6 h (but not 1 h) earlier. These results demonstrate the participation of glucocorticoid receptors in the expression of immobility in a forced swim test during the initial test.

Animals↗
PubMed1991

Swimming in a sub-adult monogenean of the genus Entobdella.

Swimming in a sub-adult monogenean parasite is reported for the first time. When detached from the substrate, a specimen of an undescribed species of Entobdella from the ventral skin surface of the cow-tailed ray, Dasyatis sephen, was found to propel itself vigorously through the water, head-first, by rapid dorso-ventral body undulations travelling in an antero-posterior direction. These waves pass in the opposite direction to the slower breathing (?) undulations exhibited by the attached parasite. Benedeniella macrocolpa from another elasmobranch host and benedeniines from teleost fishes merely made uncoordinated wriggling movements when detached from the substrate. The possible function of swimming in monogeneans is discussed.

Animals↗
PubMed1992

Active drag, useful mechanical power output and hydrodynamic force coefficient in different swimming strokes at maximal velocity.

By comparing the time of the same distance swum with and without an added resistance, under the assumption of an equal power output in both cases, the drag of 73 top swimmers was estimated. The active drag Fr(a.d.) at maximal swimming velocities varied considerably across strokes and individuals. In the females Fr(a.d.) ranged from 69.78 to 31.16 N in the front-crawl, from 83.04 to 37.78 N in dolphin, from 93.56 to 45.19 N in breaststroke, and from 65.51 to 37.79 N in back-stroke. In the males Fr(a.d.) ranged from 167.11 to 42.23 N in front-crawl, from 156.09 to 46.95 N in dolphin, from 176.87 to 55.61 N in breaststroke, and from 146.28 to 46.36 N in back-stroke. Also, the ratio of Fr(a.d.) to the passive drag Fr(a.d.) as determined for the analogical velocity in a tugging condition (in standard body position-front gliding) shows considerable individual variations. In the female swimmers variations in Fr(a.d.)/Fr(p.d.) ranged from 145.17 to 59.94% in front-crawl, from 192.39 to 85.57% in dolphin, from 298.03 to 124.50% in breaststroke, and from 162.87 to 85.61% in back-stroke. In the male swimmers variations in Fr(a.d.)/Fr(p.d.) ranged from 162.24 to 62.39% in front-crawl, from 191.70 to 70.38% in dolphin, from 295.57 to 102.83% in breaststroke, and from 198.82 to 74.48% in back-stroke. The main reason for such variations is found in the individual features of swimming technique and can be quantitatively estimated with the hydrodynamic force coefficient, which thus provides an adequate index of technique.

Adolescent↗
PubMed1996

Minimum-time running and swimming: an optimal control approach.

During analysis of the competitor's velocity in a run, strong assumptions are imposed upon the runner's tactic. It is assumed that the competitor uses his/her maximal propulsive force in short-distance events. The runner's velocity is assumed constant in long-distance races. None of these assumptions is satisfied during middle-distance races. In this study, the competitor's velocity, minimizing the time taken to cover the distance, is determined by means of extremization of linear integrals using Green's theorem (Miele's method). The model of the competitor's motion is based on two differential equations: the first one derives from Newton's second law, the second one is the equation for power balance. The theory is illustrated with two examples referring to competitive running and swimming. The minimum-time competitive run can be broken into three phases: -the acceleration, -the cruise with the constant velocity, and -the negative kick at the end of the race. The problem has a similar solution in competitive swimming, however, the acceleration is replaced by the gliding phase.

Acceleration↗
PubMed1995

Environmental and biological monitoring of chloroform in indoor swimming pools.

The presence of chloroform as the result of disinfection with sodium hypochlorite was demonstrated in the water and ambient air of indoor swimming pools. Environmental monitoring was performed in 12 indoor swimming pools in northern Italy and the level of human exposure was assessed. Biological monitoring performed by gas chromatography on human plasma and alveolar air samples evidenced that the uptake of chloroform in swimmers varies according to the intensity of the physical activity and age. The elimination of chloroform in alveolar air in one subject showed a very short half-life (from 20 to 27 min) and a complete clearance within 10 h after the end of exposure.

Breath Tests↗
PubMed1984

Beta-adrenoceptor mediated inhibition of behavioral action of desipramine and of central noradrenergic activity in forced swimming rats.

The immobility-reducing action of desipramine (DMI) in forced swimming rats was attenuated by intracerebroventricular (i.c.v.) injection of isoproterenol (ISO) and potentiated by i.c.v. atenolol (ATE), a beta 1-adrenoceptor antagonist. The effect of ISO was blocked by ATE. When administered i.c.v. in normal rats, ISO reduced the contents of 3-methoxy-4-hydroxyphenylethyleneglycol sulfate (MHPG-SO4), a major metabolite of noradrenaline, in the septal area, thalamus and hypothalamus while ATE had no effect in most of the brain regions. However, in forced swimming rats treated with DMI, ISO reduced MHPG-SO4 in 6 out of 8 brain regions tested and conversely, ATE increased the levels in the amygdala, septal area and hypothalamus. Similar to the behavioral effect, the effect of ISO was antagonized by ATE. These results support the hypothesis that central beta 1-adrenergic mechanisms inhibit the immobility-reducing action of DMI by reducing the activity of noradrenergic neurons in the brain.

Animals↗
PubMed1992

Relationship between hypothalamic noradrenergic activity and the sympathetic activity in interscapular brown adipose tissue after cold-swim stress in rats.

Noradrenaline (NA) activities in both hypothalamus and interscapular brown adipose tissue (IBAT) were simultaneously assessed before and after cold-swim stress in rats. The technique of gas chromatography-mass spectrometry was employed for the analysis of NA and its primary neuronal metabolite, 3,4-dehydroxy-phenylethylenglycol (DHPG), and the ratio of DHPG to NA was used as an index of NA activity. The ratios of DHPG/NA in both hypothalamus and IBAT were significantly elevated 5 and 20 min after cold-swim stress. Moreover, we found that there is a highly significant positive relationship between the hypothalamic DHPG/NA ratio and the ratio of DHPG/NA in IBAT (r = 0.872, p less than 0.0001). This observation strongly supports the concept in which hypothalamic NA neurons play an important role in modulating the sympathetic outflow.

Adipose Tissue, Brown↗
PubMed1993

Cold water swim stress inhibits the nociceptive responses to intrathecally administered somatostatin, but not substance P.

The effects of cold water swim stress (CWSS) on the nociceptive responses to i.t. administered substance P (SP) and somatostatin (SST) were examined. Male ICR mice, weighing about 30 g, were forced to swim in water at 20 degrees C for 3 min. In unstressed mice, i.t. injection of SP (0.1 nmol) and SST (1 nmol), respectively, produced nociceptive-related behaviors. Although CWSS had no effect on the intensity of the SP-induced nociceptive responses, CWSS significantly reduced the intensity of the SST-induced nociceptive responses. The effect of CWSS on the SST-induced nociceptive responses was blocked by naloxone (5 mg/kg, s.c.) and naltrindole (1 mg/kg, s.c.), a selective delta-opioid receptor antagonist, but not by beta-funaltrexamine (20 mg/kg, s.c.), a selective mu-opioid receptor antagonist. These results indicate that CWSS may selectively reduce the SST-induced nociceptive responses primarily through delta-opioid receptors.

Animals↗
PubMed1994

Differential mediation of cold water swim stress-induced antinociception by delta-opioid receptor subtypes in diabetic mice.

The involvement of delta-opioid receptor subtypes in cold water swim stress (CWSS)-induced antinociception in diabetic mice was compared with that in non-diabetic mice. Three-minute swim stress produced significant antinociception in both diabetic and non-diabetic mice as determined by the tail-pinch test. However, the extent of CWSS-induced antinociception in diabetic mice was significantly greater than that in non-diabetic mice. Pretreatment with naltriben, a selective delta 2-opioid receptor antagonist, significantly attenuated CWSS-induced antinociception in both non-diabetic and diabetic mice. In contrast, although 7-benzylidenenaltrexone, a selective delta 1-opioid receptor antagonist, significantly attenuated CWSS-induced antinociception in diabetic mice, it had no effect in non-diabetic mice. These results suggest that CWSS-induced antinociception in non-diabetic mice is mediated by delta 2-opioid receptors, whereas CWSS-induced antinociception in diabetic mice is mediated by both delta 1- and delta 2-opioid receptors. Furthermore, the enhanced CWSS-induced antinociception in diabetic mice may be due to the activation of delta 1-opioid receptors.

Analgesia↗
PubMed1987

Evidence that dopamine mechanisms in the nucleus accumbens are selectively involved in the effect of desipramine in the forced swimming test.

Bilateral injections of 5 or 1 (but not 0.5) micrograms sulpiride into the nucleus accumbens reduced the effect of a 7-day treatment with 10 mg/kg/day desipramine in the forced swimming test. Bilateral injections of 5 or 1 micrograms sulpiride in the caudate-putamen did not modify the anti-immobility effect of desipramine. The data support the hypothesis that dopamine mechanisms in the limbic regions of the brain of the rat are involved in the effect of repeated treatment with desipramine in the forced swimming test.

Animals↗
PubMed1992

The role of serotonin and dopamine in brain in the antidepressant-like effect of clonidine in the forced swimming test.

The effect of clonidine (0.1 mg/kg, i.p.), as a three-injection course, on behaviour in the forced swimming test was studied in rats injected intracerebroventricularly (i.c.v.) with 150 micrograms 5,7-dihydroxy-tryptamine (5,7-DHT) to destroy serotonin (5-HT) neurones or treated with 100 mg/kg (i.p.) (+/-)-sulpiride or 0.5 micrograms/0.5 microliter (-)-sulpiride in the nucleus accumbens. Clonidine significantly increased struggling and reduced floating and the effects were antagonized by both treatments with sulpiride but not by 5,7-DHT which markedly depleted 5-HT in brain. The results suggest that the mesolimbic dopaminergic system but not 5-HT neurones, plays a permissive role in the antidepressant-like effect of clonidine in the forced swimming test.

5,7-Dihydroxytryptamine↗
PubMed1982

Involvement of endogenous opioids with forced swimming-induced immobility in mice.

The present study investigated the involvement of endogenous opioid mechanisms with the immobility response induced in mice by forced swimming. Pretreatment with the narcotic antagonist naloxone (0.625--40.0 mg/kg) caused a dose-dependent decrease in the duration of immobility in mice subjected to a 10 min swim test. This effect was more pronounced in C57BL/6J mice than in BALB/C mice. A low dose of morphine (0.15 mg/kg) potentiated immobility whereas higher doses (0.625/10.0 mg/kg) had no demonstrable effect on immobility in these strains. The results suggest that release of endogenous opioids may be a physiological event promoting natural cataleptic-like behaviors in mice.

Animals↗
PubMed1986

A simple rapid swim test to determine spatial preference in the rat.

A swim test is described for the evaluation of spatial preference in untreated male rats. The test is rapid, objective and simple to perform and was able to distinguish right-left preferences in 47 rats. It is encouraged that the swim test be compared to or used in conjunction with other spatial preference tests.

Animals↗
PubMed1987

Forced swimming alters vaginal estrous cycles, body composition, and steroid levels without disrupting lordosis behavior or fertility in rats.

The purpose of the present studies was to examine how exercise affects reproductive physiology and behavior. In four separate experiments, exercise regimens of forced swimming or swimming plus running, were gradually increased in duration to a maximum of 2.5 hours. Vaginal cycles were monitored daily and after eight weeks animals were tested for sexual behavior, ability to breed, changes in body composition, circulating levels of estradiol, progesterone, and corticosterone. Total body lipids were lowered in animals that both ran and swam and parametrial fat pad weight was reduced in all exercising animals. Although exercise lowered circulating levels of ovarian steroids, elevated corticosterone levels and disrupted vaginal cycles, exercised animals exhibited normal sexual behavior and bred successfully. These data indicate that intense exercise can, under certain conditions, disrupt the mechanisms controlling vaginal cycles while the neuroendocrine mechanisms controlling sexual receptivity, ovulation, and fertility remain intact.

Animals↗
PubMed1988

Gender-specific and gonadectomy-specific effects upon swim analgesia: role of steroid replacement therapy.

Both gender-specific and gonadectomy-specific effects have been observed for the analgesic responses following continuous and intermittent cold-water swims (CCWS and ICWS respectively): female rats display significantly less analgesia than males, and gonadectomized rats display significantly less analgesia than sham-operated controls. The present study evaluated the effects of steroid replacement therapy with testosterone propionate (TP: 2 mg/kg, SC) upon CCWS and ICWS analgesia on the tail-flick and jump tests and hypothermia in sham-operated or gonadectomized male and female rats. Thirty days following surgery, rats received either no treatment, a sesame oil vehicle or TP for 14 days prior to, and then during testing. Relative to the no treatment condition, repeated vehicle injections in sham-operated rats eliminated the gender-specific, but did not affect the gonadectomy-specific effects upon CCWS and ICWS analgesia. TP reversed the deficits in CCWS and ICWS analgesia observed in both castrated and ovariectomized rats on both pain tests. TP only potentiated CCWS analgesia in sham-operated males on the tail-flick test. TP potentiated CCWS and ICWS hypothermia in gonadectomized rats and in male sham-operated rats. These data indicate that gonadal steroids play a major modulatory role in the etiology of swim analgesia, and that the observed gender effects are sensitive to possible adaptational variables.

Analgesia↗
PubMed1991

Gradient of alarm substance in the forced swimming test.

Three studies were conducted with rats to study the effects of a proposed alarm substance released during the forced swimming test. In the first study, rats were retested in water previously swum in but which had been subsequently diluted to varying degrees. When water was diluted by more than 25% the proposed alarm substance could no longer be detected. In the second study, rats were retested at various times after initial testing. This study showed that the alarm substance was still active by eight days after it had been initially released. The final study tested animals to see if the alarm substance could be depleted by repeated testing. Testing animals for more than an hour did not result in depletion of the alarm substance. These three studies suggest that the proposed alarm substance secreted by rats during the forced swimming test has considerable biological significance.

Animals↗