Decrease In Swimming Speed Research Articles

Age-related decrease in spontaneity observed in senescence-accelerated mice (SAMP10) and the involvement of the dopaminergic system in behavioral disorders

We studied age-related behavioral changes in senescence-accelerated P10/Ta mice (SAMP10) reared under specific pathogen-free (SPF) conditions. Unlike SAMP8/Ta (SAMP8), the SAMP10 did not exhibit low anxiety-like behavior in the plus-maze test and the impairment of the passive avoidance task of SAMP10 was milder than that of SAMP8. SAMP10 showed more age-related abnormal behavior than did SAMP8, such as a decrease in shock sensitivity, increases in the duration of immobility during the tail suspension and the forced swimming tests and a decrease in swimming speed in a water maze task. SAMP10 showed a significant decrease in dopamine content in the anterior cortex. Furthermore, the behavioral depression observed in SAMP10 was ameliorated by dopaminergic stimulants such as apomorphine and a sustained release formulation of thyrotropin-releasing hormone (TRH-SR), at doses having no significant effects on spontaneous motor activity. These findings suggest that the dopaminergic function may contribute to behavioral depression. The present results indicate that SAMP10 shows a greater age-related decrease in the responsiveness to averse or stressful stimuli than do the R1 and P8 strains, which suggests that SAMP10 may be a useful animal model of age-related behavioral depression or decrease in spontaneity.

Estrogen treatment alleviates NMDA-antagonist induced hippocampal LTP blockade and cognitive deficits in ovariectomized mice

Estrogen is implicated in hippocampus-dependent spatial learning as well as structural organization and electrophysiological properties of the rat hippocampus but little is known about its mechanisms of action in mice. In this study, we investigated pharmacologically whether estrogen interacts with the hippocampal N-methyl- d-aspartate (NMDA) receptors in ovariectomized mice as postulated for rats. Female C57BL/6J mice were ovariectomized at 5 months, and 2 weeks before testing at 12 months, half of them received subcutaneous estrogen pellets containing 0.18 mg of 17β-estradiol. The competitive NMDA-antagonist, 3-((±)-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP), was administered at 5.0 and 10.0 μM to block induction of long-term potentiation (LTP) in the hippocampal slice and intraperitoneally at 0.5, 2.0, and 5.0 mg/kg to impair spatial learning in the water maze. Estrogen treatment shifted the dose–response curve to CPP in both experiments. First, 10 μM CPP blocked the initiation of LTP in all mice, but 5 μM only in ovariectomized non-estrogen-treated mice. Second, final level of acquisition and probe trial performance in the water maze were less affected by high doses of CPP in the estrogen-treated ovariectomized mice than in non-treated group. In control tests for motor side effects, estrogen treatment did not reduce the tendency of CPP to decrease locomotor activity in the open field and impair balance on a rotating rod, and estrogen by itself decreased swimming speed as did CPP, but these effects did not interact. Our findings support the notion that estrogen treatment increases the number of active NMDA-receptors in the mouse hippocampus.

The effect of progressive hypoxia on swimming activity and schooling in Atlantic herring

Schools of herring exposed to progressive hypoxia show a peak in velocity during severe hypoxia, at 15–34% oxygen saturation, followed by a decrease in swimming speed until school disruption occurred. The observed increase in swimming speed during severe hypoxia reveals a graded response, since the lower the fish's swimming speed prior to severe hypoxia (U95−50, the speed at oxygen saturations between 95 and 50%), the greater the relative increase in swimming speed. The oxygen saturations at which both peak velocity and school disruption occurred were lower for fish with lowest U95−50, suggesting that the fish with the slowest speed U95−50 reach their critical PO2 (at which there is respiratory distress) last, i.e. at lower oxygen saturation. At a functional level, it is suggested that herring encountering hypoxia increase their speed in order to find more favourable conditions, and the magnitude of this increase is modulated by their respiratory distress. It is also hypothesised that the observed increase in speed may be related to an increase in the rate of position shifting within the school. Since the oxygen saturation at which the response to hypoxia occurs and the magnitude of the response are related to the fish's preferred speed prior to severe hypoxia, it is suggested that such a preferred speed should be measured in experiments testing the effect of hypoxia on fish behaviour.

Cerebral oligaemia episode triggers free radical formation and late cognitive deficiencies.

Sixty minutes of cerebral oligaemic hypoxia, induced by bilateral clamping of the carotid arteries (BCCA) in pentobarbital-anaesthetized normotensive rats, induces a late progressive cognitive decline when compared with sham-operated controls. Analysis at BCCA of hippocampal metabolism using microdialysis showed increased release of glutamate, aspartate and gamma-aminobutyric acid, followed by a progressive rise in the formation of hydroxyl free radicals measured as 2,3-dihydroxybenzoic acid (2,3-DHBA), their reaction product with salicylate, though only in the re-perfusion phase. In the striatum increased dopamine release occurred during BCCA, whereas glutamate and aspartate showed an increase only during the late re-perfusion phase. gamma-Aminobutyric acid (GABA) concentration increased during BCCA and early re-perfusion. An increase in 2,3-DHBA was seen during BCCA, and persisted over 2 h of re-perfusion. Six and 13 months after surgery, though not as early as 3 months, BCCA-treated rats perform worse than sham-operated controls in a water-maze, where decreased swimming speed reveals striatal dysfunction, while hippocampal dysfunction manifested as diminished spatial bias. These results show that cerebral oligaemia, similarly to cerebral ischaemia, leads to increased extracellular dopamine, aspartate and glutamate, and the production of hydroxyl radicals in structures associated with learning and memory processes. Unlike cerebral ischaemia, in cerebral oligaemia the appearance of spatial memory deficits is delayed.

Simultaneous evaluation of spatial working memory and motivation by the allocentric place discrimination task in the water maze in rats.

In order to evaluate learning and memory deficits separately from and simultaneously with motivational, motor and sensory impairments in identical animals, we developed the allocentric place discrimination task test using a water maze in rats. For this assessment task, two similar, visible platforms, one was fixed and the other was floating, were simultaneously present in a pool, and the working memory of the allocentric place discrimination task was evaluated. After training, the task accuracy was high about 85% correct and animals were used repeatedly. The accuracy decreased significantly when the pool was surrounded with a black curtain. Muscarinic receptor antagonist scopolamine 0.5 mg/kg selectively impaired the accuracy. Muscle relaxant dantrolene 10 mg/kg selectively decreased swimming speed. Under low motivational condition (warm water), still time increased and swimming speed decreased, but the accuracy was not affected. Similar to warm water, opioid receptor agonist morphine 15 mg/kg increased still time and decreased swimming speed. These results suggest that the allocentric place discrimination task is useful in evaluating spatial working memory ability independently of and concurrently with also visual, motor ability and motivation in identical animals.

Effects of oral administration of the competitive N-methyl- d-aspartate antagonist, CGP 40116, on passive avoidance, spatial learning, and neuromotor abilities in mice

The effects were investigated of the potent competitive N-methyl- d-aspartate (NMDA) receptor antagonist CGP 40116 [D-(E)-2-amino-4-methyl-5-phosphono-3-pentenoic acid] on the performance of mice in water maze and passive avoidance tasks, and in wire suspension, rotarod, and cage activity tests. The drug was administered per os (p.o.) in its anticonvulsant dose range. CGP 40116 dose-dependently impaired passive avoidance learning when given before, but not when given after training. The antagonist (5, 10, and 20 mg/kg, administered 4 h before each training session) dose-dependently affected water maze acquisition, and impaired retention test performance in both hidden- and visible-platform water maze tasks. In addition, the drug dose-dependently decreased swimming speed during water maze acquisition. Repeated administration of CGP 40116 (20 mg/kg, p.o.) persistently decreased cage activity and wire suspension test performance, whereas motor coordination and equilibrium on the rotarod apparatus remained unimpaired. In our administration protocol, no tolerance was found to the effects of the drug on passive avoidance learning and neuromotor abilities. The parallel effects of CGP 40116 on memory and motor performance are discussed, and it was concluded that the antagonist impairs neuromotor abilities and also induces memory impairments which cannot be entirely reduced to motor interference.

Characterization of polar-flagellar-length mutants in Vibrio alginolyticus.

Vibrio alginolyticus has two types of flagella, polar (Pof) and lateral (Laf). From a Laf-defective mutant (Pof+Laf-), polar-flagellar-length mutants which have short Pof and long Pof were isolated. The mean lengths of the helical axis in wild-type, short and long Pof were 5.5.0.9 μm, 2.5.0.6 μm and 11.2.3.6 μm, respectively. The swimming speeds of the short- and long-Pof mutants were slower than that of the wild-type strain. The relationship between swimming speed and flagellar length in a population of mutant cells was examined. In the short-Pof mutant, the decrease of swimming speed seemed to be derived from the decrease in flagellar length. In the long-Pof mutant, there was almost no correlation between swimming speed and flagellar length, and the slow swimming was explained by the helical shape of the flagella, whose pitch and radius were 1.4 μm and 0.062 μm, respectively, whereas those of the wild-type flagella were 1.5 μm and 0.16 μm. The relative amounts of the various molecular components of the long Pof were different from those of the wild-type or the short Pof. This seems to be the reason for the difference in flagellar shape and length, though the mutation may be pleiotropic and affect flagellar function or regulation.

Analysis of bacterial swimming speed approaching a solid–liquid interface

AbstractPrevious experimental studies have found that surface interactions significantly affect the transport of motile bacteria through small tubes, along solid surfaces, and through porous media. However, the role that hydrodynamic forces play in the interactions between solid surfaces and motile bacteria remains unclear. In this study, the swimming speeds of populations of Escherichia coli bacteria were measured near (< 10 μm) and far (>10 μm) from a flat glass surface at four ranges of orientations to the surface (0°–45°, 45°–90°, 90°–135°, and 135°–180°). Populations of bacteria close to the surface and moving in the orientation range most perpendicular (0–45°) to the surface experienced the greatest change in the swimming speed when compared to the population in the same orientation range located far from the surface. The decrease in swimming speed experienced by this population was on the same order as that predicted by hydrodynamic models of bacterial swimming near surfaces.

The functional morphology of caudal lamellae in coenagrionid (Odonata:Zygoptera) damselfly larvae

During their later instars, coenagrionid damselfly larvae reduce their relative investment in lamellae. Caudal lamellae play a role in swimming by allowing a larva to take advantage of its body size when at least one lamella is present, and this benefit increases with larval size. The removal of the first and/or second lamella generally results in a fixed and measurable decrease in swimming speed. When all lamellae are removed, larvae suffer a dramatic reduction in swimming speed. Ischnura posita(Hagen) and Enallagma civile(Hagen) always swim faster than equal sized Telebasis salva(Hagen) and Argia translata(Hagen) when at least one lamella is present. The swimming speed of the three lentic forms I. posita, E. civile,and T. salvais more affected by lamella loss than the lotic form A. translata.These last three relationships do not change ontogenetically. Caudal lamellae surface area does not increase as fast ontogenetically as would be expected for a gas exchange organ. The breaking joints, which hold the lamellae to the body, do not grow isometrically with body size, but do grow isometrically with lamellar mass. This suggests that the lamellae may be retained in proportion to investment (mass).

Activity and swimming speed at time of first feeding of halibut (Hippoglossus hippoglossus) larvae

Atlantic halibut larvae show an increase in activity, together with a decrease in swimming speed during active periods, occurring from day 26 onwards, which corresponds approximately to 50% yolk absorption.

Anoxic Depression of Spontaneous Locomotor Activity in Crucian Carp Quantified by A Computerized Imaging Technique

ABSTRACT The crucian carp (Carassius carassius L.) is one of the most anoxia-tolerant fishes. An important strategy used by the crucian carp to survive anoxia is to lower its rate of energy consumption. Anoxia-tolerant fish are known to utilize simultaneously two different strategies for reducing energy consumption during anoxia, the first being a reduction in locomotor activity and the second being a depression of cellular energy demands. Nevertheless, the reduction in locomotor activity during anoxia has never been measured quantitatively. This lack of information is apparently because technical problems have prevented the measurement of spontaneous locomotor activity in fish. It is now possible to use computerized video-imaging techniques to record the movement of an animal continuously. By the use of such a technique, we show that crucian carp respond to anoxia (330min at 9°C) by rapidly decreasing their locomotor activity (spontaneous swimming distance) to about 50% of that displayed during normoxia. Frequency diagrams of spontaneous swimming speed showed no bimodality and indicated a general decrease in swimming speed from a median value of 1.82 m min−1 during normoxia to 0.82 m min−1 during anoxia. It is tentatively estimated that the anoxic depression of locomotor activity corresponds to a 35–40% reduction in total energy consumption. The role of locomotor activity in fish energy budgets is discussed.

Cholinergic effects on spatial exploration and its memory.

In their first swim in an unfamiliar circular swimming pool, control rats showed declines in average swimming speed and in the time spent in the perimeter of the pool. Both declines were antagonized by the muscarinic antagonist scopolamine, but not by methylscopolamine, a muscarinic antagonist that crosses the blood-brain barrier only poorly, indicating that these declines depend upon central cholinergic activity. In the first minute of a second swim 3 days later, control rats spent a much longer time in the central region of the pool than in the first minute of the first swim. This modification of behaviour by previous experience suggests that a long-term memory of the first swim was formed. Scopolamine, but not methylscopolamine, administered before the first swim attenuated this modification of behaviour. Pilocarpine, administered shortly after scopolamine before the first swim, significantly normalized all the scopolamine-induced changes, whereas oxotremorine and arecoline normalized only habituation of perimeter preference; agonists administered alone decreased swimming speed and perimeter preference without affecting their rates of decline. The results suggest that in this test, different cholinergic mechanisms are involved in habituation of swimming speed and habituation of perimeter preference.

Separating the Effects of Temperature and Viscosity on Swimming and Water Movement by Sand Dollar Larvae (Dendraster Excentricus)

ABSTRACT The small size and slow movement of aquatic, microscopic organisms means that the viscosity of water has a predominant influence on their motion. Temperature, through its effects on physiological processes, also influences motion. Because water viscosity is physically coupled to temperature, changes in temperature can influence the activity of microscopic organisms through both physiological and physical means. To partition these effects, we artificially altered seawater viscosity and, at two temperatures, we measured swimming speed and water movement by larvae of the sand dollar Dendraster excentricus. Over an environmentally relevant, 10-degree drop in water temperature (22 to 12°C), swimming speed was reduced by approximately 40% and water movement was reduced by 35%. 40% of the decrease in swimming speed and 55% of the decrease in water movement were accounted for by increases in viscosity alone. The physical effects of viscosity can therefore make up a large component of the effect of temperature on activity of microscopic organisms. If uncorrected for effects of viscosity, temperature coefficients such as Q10 values can overestimate the influence of temperature on the physiological processes that underlie the generation of motion at small spatial scales. These changes in viscosity may cause substantial reductions or increases in swimming and feeding rates that are biologically relevant. Environmental variation in viscosity due to temperature fluctuations could lead to temperature responses or adaptations that are nonphysiological.

Thermal constraints on swimming performance and escape response of northern water snakes (Nerodia sipedon)

We examined the influence of body temperature on swimming speed of northern water snakes (Nerodia sipedon) and determined how variation in water temperature influenced their escape response. In a laboratory experiment, swimming speed increased as a function of water temperature and body size. Swimming speed was less thermally dependent at temperatures approximating the snakes' normal range of activity, suggesting that selection has favoured increased performance breadth at this range. In the field, basking snakes retreated to water when approached. Despite a decrease in swimming speed at lower temperatures, and the cost associated with reduced metabolic rate due to loss of body temperature, however, flight distances were independent of water temperature. We found that basking snakes retreated to water sooner when perched at lower heights, possibly indicating that N. sipedon are more vulnerable to predators when on low perches. Predicting water snake escape behaviour may require not only knowledge of variation both among snakes and in their environment, but also a better understanding of the interaction between the snakes and their natural predators.

The effects of noradrenergic neurotoxin, DSP-4, on the performance of young and aged rats in spatial navigation task

The present study investigated whether an overactive noradrenergic system is related to the impairment in learning/memory in aged subjects. The effects of partial noradrenaline depletion (using the noradrenergic neurotoxin DSP-4) on the acquisition of a water maze task was investigated in young and aged rats, and hippocampal noradrenaline content was correlated with spatial learning performance in similar rats. DSP-4 treatment impaired markedly the acquisition of the water maze task in aged rats, but improved it slightly in young rats. DSP-4 treatment decreased swimming speed, and this effect tended to be more marked in young rats. In the group of control rats, hippocampal noradrenaline tended to correlate positively with spatial bias in aged rats (the rats with the highest noradrenaline content in the hippocampus tended to have the best spatial learning/memory), but negatively in young rats. These results do not support the hypothesis that spatial learning/memory impairment is due to an overactive noradrenergic system in aged rats. Further studies are needed to clarify the reasons of the marked age-related difference in the effects of DSP-4 on the performance of water maze task in rats.

Behavioral responses of the marine tintinnid Favella sp. to phytoplankton: influence of chemical, mechanical and photic stimuli

Computerized motion analysis was used to experimentally investigate the locomotory responses of a tintinnid, Favella sp., to phytoplankton and to chemosensory and mechanosensory stimuli associated with the presence of phytoplankton. When exposed to increased concentrations of the dinoflagellate Heterocapsa triquetra (strain HT984), Favella show transient change in behavior which result in a decrease in swimming speed, increase in turning rate and a decrease in net to gross displacement ratio; this should result in the aggregation of Favella in patches of the dinoflagellate. Similar behavioral responses are elicited by exposure to exudates of H. triquetra and to plastic beads of approximately the same size as the alga. When Favella was exposed to other phytoflagellates or their exudates, the behavioral responses were less pronounced or absent. Favella do not respond to beads < 6 μm; for larger beads, the response appears to depend on the concentration of beads. Favella do not exhibit a phototaxis or photokinesis but they do have diel behavior patterns that may be entrained by the light cycle. These diel changes in locomotory behavior may increase the probability of encounter with food patches.

Swimming pattern as an indicator of the roles of copepod sensory systems in the recognition of food

The roles of copepod sensory systems in the recognition of food were investigated using the “Bugwatcher”, a video-computer system designed to track and describe quantitatively the swimming patterns of aquatic organisms. The swimming behavior of the copepodPseudocalanus minutus in the presence of phytoplankton is characterized by a decrease in average swimming speed and an increase in “pause” behaviors compared to its swimming behavior in filtered seawater. Copepods exposed to chemosensory stimulation alone (filtered phytoplankton exudate) exhibited an increase in average swimming speed and an increase in the number of “burst” swimming behaviors. When exposed to a novel, non-food chemosensory stimulus (morpholine), no change in swimming behavior was observed unless the copepods had been conditioned to this odor in the presence of phytoplankton. Copepods exposed to mechanosensory stimulation alone (plastic spheres) exhibited a decrease in swimming speed and an increase in pause behaviors. When exposed to both forms of stimulation simultaneously (phytoplankton exudate and plastic spheres), a further decrease in swimming speed and increase in pause behaviors occurs, yielding a swimming pattern similar to that found in the presence of phytoplankton. This analysis of swimming pattern indicates that both chemoreception and mechanoreception contribute to the recognition of food inP. minutus.

Decreased Swimming Speed Following Augmentation Mammaplasty

Decreased Swimming Speed Following Augmentation Mammaplasty

Effect of Dummy Telemetry Transmitters on Stamina of Atlantic Salmon (Salmo salar) Smolts

Effects of three different-sized, internally placed dummy ultrasonic transmitters and one size externally placed dummy radio transmitter on swimming performance of Atlantic salmon (Salmo salar) smolts were determined. Critical swimming speeds were similar for fish in control groups and two of the groups tagged with internal transmitters. The widest internal dummy tag (19 mm long × 10 mm diameter) caused a significant (P &lt; 0.05) decrement in swimming performance; the size representing the smallest available transmitters (33 mm long × 8 mm diameter) did not. Linear regression analysis of this latter group demonstrated that larger smolts carried the transmitter better than smaller smolts. Results indicated that fish longer than about 20 cm can successfully be tagged with the available transmitter. Externally placed dummy radio transmitters caused a highly significant (P &lt; 0.01) decrease in swimming speed compared with that of controls.