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PubMedDate not supplied

Alterations in core body temperature, locomotor activity, and corticosterone following acute and repeated social defeat of male NMRI mice.

Repeated social defeat of male NMRI mice, coupled with the stress of continuously living opposite a dominant animal, induces a citalopram-reversible increase in anxiety. The experiments reported in the present paper were performed in an attempt to further validate this paradigm by studying the effects of acute and repeated social defeat on corticosterone and the circadian rhythms of core body temperature and locomotor activity, measured by telemetry. Acute social defeat induced a large (controls: 37.14+/-0.29 degrees C; subordinates: 39.79+/-0.33 degrees C) increase in core body temperature and corticosterone (controls: 30.14+/-2.70 ng/ml; subordinates: 89.62+/-9.25 ng/ml). Repeated social defeat (24 defeats) induced a chronic elevation in core body temperature across 24-h (controls: 36.62+/-0.04 degrees C; subordinates: 37.11+/-0.16 degrees C) in subordinate animals and a very large increase in corticosterone (controls: 28.60+/-1.27 ng/ml; subordinates: 441.52+/-8.86 ng/ml). These results illustrate that the chronic social defeat procedure described in this paper induces a state of chronic stress in the subordinate animals. Further studies are warranted to ascertain if the chronic hyperthermia and increases in corticosterone observed in the subordinate animals could be attenuated by chronic antidepressant treatment, thus further extending the predictive validity of this model.

Animals↗

PubMed2002

Alleviating effects of plant-derived fragrances on stress-induced hyperthermia in rats.

In the present study, the effects of exposure to plant-derived odors on the autonomic and behavioral responses to novel environment were examined in rats. Male rats (n=42) carrying a telemetry transmitter were individually housed, and on the test day each rat was transferred to a new cage containing bedding that had been sprayed immediately before testing with 200 microl of 0.03% dilution of either lavender essential oil, green leaf odor (a mixture of hexenol and hexenal), alpha-pinene, or solvent (triethyl citrate) as a control. Following the transfer to this novel environment, the body temperature of the rats increased by nearly 1 degrees C, showing a stress-induced hyperthermia. Stress-induced hyperthermia was attenuated by the green odor and the alpha-pinene, but not by the lavender or solvent. There was no clear effect of fragrances on heart rate or behavioral responses. These results suggest that plant-derived fragrances, such as green odor and alpha-pinene, have calming effects on autonomic stress response to novel environments.

Animals↗

PubMed2002

A study of VitalView for behavioural and physiological monitoring in laboratory rats.

We describe the use of a commercially available telemetry and data acquisition system to record heart rate, body temperature and activity of freely behaving rats with transmitters that operate without batteries (transponders). The system uses PDT 4000HR E-Mitters (Mini Mitter, OR, USA) to acquire animal temperature, heart rate and motor activity data. E-Mitters obtain power from a radiofrequency field produced by an ER-4000 energizer/receiver so that transponders can collect data on heart rate, body temperature and gross motor activity. ER-4000 energizers/receivers are designed to be placed below the animals' cage. Data output from receivers is managed by a Windows PC-based data acquisition system, VitalView. In this study, we report that a good correlation exists between VitalView and Powerlab for the determination of heart rate and between intra-abdominal (telemetric) and colonic body temperature (rectal digital thermometer) in rats. Assessment of this system by using agents that have well-documented effects on heart rate, body temperature and locomotor activity have also been determined. An additional feature of VitalView is the incorporation of behavioural inputs (feeding monitors to monitor duration and frequency of feeding and a lickometer to monitor drinking bouts) into the data acquisition system designed primarily to acquire data from the implanted transponders. Circadian rhythms for all parameters were established in rats with E-Mitters implanted. VitalView may be used for the determination of multiple parameters in freely behaving animals using transponders, which operate without batteries. This capability is unique in its field and represents a recent advance in biotelemetric monitoring of laboratory animals.

Animals↗

PubMed2003

Cardiovascular and metabolic responses to fasting and thermoneutrality in Ay mice.

Several lines of evidence support a role for reduced melanocortin signaling in the regulation of metabolic rate and cardiovascular function during negative energy balance. We tested the hypothesis that agouti yellow (B6.Cg-A(y)) mice would exhibit blunted physiologic responses to fasting and thermoneutrality. Male B6.Cg-A(y) mice (A(y); n=11, 34+/-2 g) and lean B6 littermates (B6; n=7, 26+/-2 g) were implanted with telemetry devices and housed in metabolic chambers (T(a)=23 degrees C) to determine the effects of a 24-h fasting and exposure to thermoneutrality (T(a)=30 degrees C) on mean arterial pressure (MAP), heart rate (HR), AP and HR variability (time and frequency domain), oxygen consumption (VO(2)), and locomotor activity. A(y) mice exhibited elevated baseline light-period MAP (A(y): 113+/-4; B6: 99+/-3 mm Hg) and VO(2) (A(y): 1.82+/-0.08 vs. B6: 1.45+/-0.13 ml/min) with no difference in HR (A(y): 530+/-12 vs. B6: 548+/-19 bpm). At 12-24 h after food removal, A(y) mice displayed normal fasting-induced bradycardia (A(y): -106+/-12; B6: -117+/-19 bpm) and reduction in VO(2) (A(y): -0.19+/-0.04 vs. B6: -0.28+/-0.05 ml/min), but with augmented hypotension (A(y): -9+/-2 vs. B6: -0.5+/-2 mm Hg) and blunted hyperactivity (A(y): 27+/-23 vs. B6: 122+/-42 m/11 h). Fasting was associated with increased HR variability in both time and frequency domain in B6 but not A(y) mice. Exposure to thermoneutrality produced comparable reductions in MAP, HR, and VO(2) in both strains. We conclude that inhibition of melanocortin signaling is not requisite for, but participates in, the metabolic and cardiovascular responses to negative energy balance.

Agouti Signaling Protein↗

PubMed1999

Prostaglandin E2-induced fever in young and old Long-Evans rats.

Aging is associated with a blunted or absent fever response to naturally occurring infections or to the peripheral administration of bacterial products and proinflammatory cytokines. We have recently shown that old Long-Evans rats are not defective in their capacity to develop a fever in response to brain administration of interleukin-1beta (IL-1beta). Here, we investigated the fever response of young (3-5-month) and old (24-26-month) Long-Evans rats to the intracerebroventricular (i.c.v.) microinfusion of prostaglandin E2 (PGE2), a final common mediator for the production of fever in the brain. Core body temperature was monitored by telemetry in freely moving rats. i.c.v. administered PGE2 (100 ng) induced comparable increases in body temperature in young and old Long-Evans rats. In the two groups, PGE2-induced fever was similar both in latency-to-peak fever and maximal fever response. These data, and the previous data on IL-1beta, demonstrate that the brains of old and young rats are similar with respect to fever generation in response to the i.c.v. administration of two classes of immunomodulators.

Aging↗

PubMed2000

Effect of dose and day of treatment on uterine response to oxytocin in mares.

To determine the effect of dose and day of oxytocin treatment on intrauterine pressure, 6 normal mares were treated with 10 or 25 IU oxytocin 2 days before ovulation, on the day of ovulation and 2 days after ovulation. Intrauterine pressure (IUP) was measured using micro-tip-catheters (one placed intrauterine, a second and third serving as reference sensors in the vagina and external to the mare) and transmitted by telemetry for 30 min to establish a baseline before saline was administered, iv, and for an additional 30 min after saline administration. Oxytocin was then given, iv, and IUP was recorded for 60 min. No change in IUP was observed after saline injection. The administration of both 10 (n=16) and 25 (n=10) IU oxytocin induced a response (P<0.01). The intensity of response depended on the day of administration (P<0.01) and the dose of oxytocin (P<0.001). The variation of response was significantly greater after 10 IU oxytocin (CV 15.78%) compared with 25 IU oxytocin (CV 6.42%). The uterine response was greatest on Day 2 prior to ovulation and lowest on Day 2 after ovulation. The response was negatively correlated to increasing plasma progesterone (10 IU oxytocin: r = -0.435, 25 IU oxytocin: r = -0.265). There was no correlation between the uterine response and plasma estradiol-17beta concentration (P<0.01). In conclusion the results of this study show that oxytocin administration to mares before ovulation provides a greater response than after ovulation. A decline in the intensity of response after ovulation can be compensated for with a higher dose of oxytocin. Furthermore, the use of the multiple catheter technique is an effective method for assessing changes in uterine pressure.

Animals↗

PubMedDate not supplied

Ground and on-orbit command and data handling architectures for the Active Rack Isolation System microgravity flight experiment.

The Active Rack Isolation System [ARIS] International Space Station [ISS] Characterization Experiment, or ARIS-ICE for short, is a long duration microgravity characterization experiment aboard the ISS. The objective of the experiment is to fully characterize active microgravity performance of the first ARIS rack deployed on the ISS. Efficient ground and on-orbit command and data handling [C&DH] segments are the crux in achieving the challenging objectives of the mission. The objective of the paper is to provide an overview of the C&DH architectures developed for ARIS-ICE, with the view that these architectures may serve as a model for future ISS microgravity payloads. Both ground and on-orbit segments, and their interaction with corresponding ISS C&DH systems are presented. The heart of the on-orbit segment is the ARIS-ICE Payload On-orbit Processor, ARIS-ICE POP for short. The POP manages communication with the ISS C&DH system and other ISS subsystems and payloads, enables automation of test/data collection sequences, and provides a wide range of utilities such as efficient file downlinks/uplinks, data post-processing, data compression and data storage. The hardware and software architecture of the POP is presented and it is shown that the built-in functionality helps to dramatically streamline the efficiency of on-orbit operations. The ground segment has at its heart special ARIS-ICE Ground Support Equipment [GSE] software developed for the experiment. The software enables efficient command and file uplinks, and reconstruction and display of science telemetry packets. The GSE software architecture is discussed along with its interactions with ISS ground C&DH elements. A test sequence example is used to demonstrate the interplay between the ground and on-orbit segments.

Acceleration↗

PubMedDate not supplied

Abnormal small-bowel motility demonstrated by radiotelemetry in a patient with irritable colon.

Jejunal motility was recorded for 47 h by telemetry from a tethered ingested radio-pill in a patient with irritable colon. In fasted controls, motor complexes are as frequent at night as during the day; the patient with irritable colon had a pronounced reduction in complexes when awake. Two prolonged episodes of pain were associated with irregular contractile activity, and ended when cyclical interdigestive activity resumed. This study suggests that irritable colon may be a disorder affecting the upper digestive tract.

Colon↗

PubMed1998

Influence of sino-aortic barodenervation on the cardiovascular effects of imidazoline-like drugs.

Earlier findings have shown that hypotensive effects of centrally acting drugs, such as clonidine, are enhanced in animals after denervation of arterial baroreceptors. The purpose of this study was to investigate the dynamic of changes in arterial pressure, heart rate and hypotensive effects of clonidine, rilmenidine and moxonidine in Wistar rats after sino-aortic denervation (SAD) using radio-telemetry. SAD was followed by significant elevation of arterial pressure lability (the standard deviation of the mean arterial pressure), while the baseline mean arterial pressure (MAP) and heart rate in barodenervated rats (12 days after SAD) was similar to intact rats. The hypotension produced by clonidine, rilmenidine and moxonidine was much greater in SAD rats than in intact rats. The study suggests that baroreflex mechanisms are not only important for maintaining levels of blood pressure in the very short term, but also for buffering the effects of centrally acting antihypertensive drugs.

Animals↗

PubMed2003

Sleep after differing amounts of conditioned fear training in BALB/cJ mice.

Shock training and auditory cues associated with shock produce alterations in sleep that can be long-lasting in BALB/cJ (C) mice. We examined sleep in C mice after different amounts of shock training, and after cues with different strength cue-shock associations. Mice were implanted with transmitters for determining sleep via telemetry. After baseline sleep recording, the mice were trained (between 08:00 and 09:00 h) to associate a cue (tone) with footshock in either single shock training (SST: a single tone-shock pairing) or multiple shock training (MST: 15 tone-shock pairings) conditions. For testing, the mice were presented 15 cues (tone only) in their home cage between 10:45 and 11:00 h on post-training days 6, 13, 20, 27, and 34 (Cue 1 to Cue 5) following shock training. Sleep was recorded for two days after shock training or cue presentation. A separate group of mice received 15 tone-shock pairings and had their sleep recorded for 10 consecutive uninterrupted days. Both SST and MST mice showed decreases in rapid eye movement sleep (REM) after shock training, with the larger effect in the MST mice. Only MST mice showed significant reductions in REM in response to the fearful cues, and longer-term alterations in sleep could be observed even on the day after cue presentation. These results indicate that reminders of an aversive event can impact sleep for prolonged periods, and that the degree of the impact varies with amount of training.

Acoustic Stimulation↗

PubMed1997

Endogenous CCK inhibits colonic contractions in unrestrained conscious rats.

As cholecystokinin octapeptide (CCK-OP) and feeding have been reported to relax the circular muscle contractions of the proximal colon in unrestrained conscious rats under fasting conditions, the, action of cholecystokinin, released after duodenal infusion of a low residual diet of clinimeal, was studied on the motor activity of the proximal colon in unrestrained conscious rats. We used an implantable telemetry system with a miniature strain gauge force transducer introduced into the rat proximal colon. By using a specific radioimmunoassay system for CCK, plasma levels of CCK before and after duodenal infusion of clinimeal (0.5, 1.0, 2.0 ml) were determined at 0, 5, 10, 20, 30, 60 min in the portal blood. The clinimeal infusion caused a significant increase in CCK levels of the portal plasma during 5 and 30 min. This increase was in a dose-dependent manner. In accordance with this increase in plasma CCK, the motor activity of the proximal circular muscle was suppressed significantly. A bolus injection of the CCK A receptor antagonist, loxiglumide, CR 1505 (0.1, 0.5 and 1.0 mg/kg ip), prior to clinimeal blocked the inhibitory action of CCK on the motor activity in a concentration-dependent manner. These data suggest that endogenous CCK released by a residual diet is involved in the mechanism of inhibition of motor activity in the proximal colon.

Animal Feed↗

PubMed2002

Software for temporal gait data analysis.

This study presents a computer program, developed to support a low-cost, portable telemetry system that has been designed to assess footfall timing. This software frees the user from data processing and allows concentration on data analysis. The new technique has been applied with accuracy and reliability to the analysis of the gait of orthopedic patients, athletes, mountaineers, etc. The subroutines developed for data acquisition, storage and analysis are explained in detail, and an example is presented.

Data Interpretation, Statistical↗

PubMed2002

The effects of acute and chronic alpha melanocyte stimulating hormone (alphaMSH) on cardiovascular dynamics in conscious rats.

Alpha melanocyte stimulating hormone (alphaMSH) has been demonstrated to have regulatory functions in the periphery and central nervous system (CNS). alphaMSH plays a central role in the regulation of metabolic balance such as decreasing food intake, increasing sympathetic outflow and hypothalamic/pituitary function. Our laboratory has investigated the actions of alphaMSH on sympathetic and cardiovascular dynamics using anesthetized animals. In this study we determined both the acute and chronic effects of alphaMSH on cardiovascular and metabolic dynamics in conscious unrestrained rats. Animals were each implanted with a radio-telemetry transmitter for recording of cardiovascular parameters and subsequently instrumented with intracerebroventricular (ICV) cannulas. The acute ICV administration of alphaMSH significantly increased the mean arterial pressure (MAP) and heart rate (HR) when compared to artificial cerebrospinal fluid (ACSF) controls. On the other hand chronic alphaMSH infusion resulted in an initial increase in MAP and HR lasting for 2 days followed by a decrease in MAP. Chronic alphaMSH administration decreased physical activity and food intake but not weight gain. We conclude that in the conscious unrestrained animal the acute administration of alphaMSH increased MAP and HR, however, chronic infusion is associated with decreased MAP, physical activity and food intake.

Animals↗

PubMed2000

Effects of ambient light on body temperature regulation in resting and exercising rats.

We investigated the effects of environmental light and darkness on thermoregulation during both daytime and nighttime by monitoring body temperature (T(b)) and physical activity of rats using a telemetry system. Experiments were performed in both resting and exercising rats. In resting rats, lights-off during the daytime resulted in an increase in both T(b) and activity. Conversely, during the nighttime, T(b) decreased with the lights-on stimulus despite the fact that the activity was left unchanged. Treadmill exercise (10 m/min) always increased T(b) from the basal resting level. In both daytime and nighttime, exercising rats exhibited a persistent T(b)-rise when lights were on. However, in the lights-off condition at nighttime, the T(b) of exercising rats increased to a level significantly higher than that of exercising rats with the lights-on. Our results suggest that light at nighttime causes the suppression of T(b) in both resting and exercising rats.

Animals↗

PubMed2003

Cardiovascular function and circadian patterns in rats after area postrema lesions or prolonged food restriction.

The role of the area postrema (AP) in baseline cardiovascular function was evaluated by radio telemetry in rats with lesions of AP (APX), along with the effect of APX on circadian patterns of cardiovascular function and ingestive behavior. Despite lesion-induced hypophagia and body weight loss, APX did not affect circadian patterns of mean arterial pressure (MAP), heart rate (HR), or ingestion but did cause a substantial decrease (-60 bpm) in resting HR. The bradycardia was not attributable to weight loss, as resting HR in weight-matched controls, though decreased from baseline, was significantly greater than that in rats with APX. In weight-matched controls, HR increased slightly when weight returned to baseline; however, the bradycardia persisted in rats with APX. These results suggest that AP contributes to resting HR, independent of weight loss or changes in circadian patterns of HR or MAP.

Animals↗

PubMed1999

The effect of indomethacin on the cytokine cascade and body temperature following burn injury in rats.

This study investigates the hypothesis that indomethacin's ability to prevent "fever" following burn injury in rats is mediated via decreased plasma concentrations of IL-6, the putative mediator of increased body temperature. Sprague-Dawley rats had radio transmitters and osmotic pumps containing indomethacin placed in the peritoneal cavity. Seven days later full thickness scald burns to 50% of the body surface area were produced. Following burn injuries, daily blood samples were obtained from a carotid catheter for assay of lipopolysaccharide (LPS), interleukin-1alpha (IL-1alpha), IL-1beta, tumor necrosis factor-alpha (TNF-alpha) and IL-6. In addition, body temperature (T(B)) and activity index were obtained every five minutes by telemetry. There were four experimental groups: burn + indomethacin (B-In); burn + polyethylene glycol (Peg) (B-Peg); control + indomethacin (C-In); and control + Peg (C-Peg). Burned animals demonstrated a significant two-fold increase in plasma IL-1alpha levels (p=0.004) and a seven-fold increment in IL-6 (p=0.0001) through the 7th PBD, and indomethacin administration had no significant effect upon the cytokine plasma levels. There were no significant increases in IL-1beta, TNF-alpha or LPS in any group. Indomethacin eliminated the chronic increase in T(B) following burn injury, and this effect was not produced by changes in plasma levels of the endogenous pyrogens IL-1alpha and IL-6.

Analysis of Variance↗

PubMed1999

Hypothalamic serotonergic activity correlates better with brain temperature than with sleep-wake cycle and muscle tone in rats.

The activity of the serotonergic system varies in phase with the sleep-wake cycle, which is associated with changes in several physiological functions, including electroencephalographic activity, brain temperature, and locomotion. The aim of the present study was to clarify which of these parameters correlates better with serotonergic activity in spontaneous conditions. Voltammetric recordings by telemetry of serotonergic metabolism in the medial preoptic area and polygraphic recordings of sleep-wake activity (by means of electroencephalographic delta band, brain cortical temperature and neck electromyographic activity recordings) were simultaneously performed in freely moving rats. Univariate analyses of variance revealed that each variable under investigation was statistically correlated with serotonergic metabolism. When the variables were entered into the model simultaneously, both partial correlation and step-wise multiple regression analyses indicated that the highest correlation exists between serotonergic metabolism and brain cortical temperature. The present data show that serotonergic activity in the medial preoptic area is closely linked to physiological changes in brain temperature.

Analysis of Variance↗

PubMedDate not supplied

[Considerations relating to the choice of criteria of automatic detection in tele-E.E.G (author's transl)].

The authors retrace their pragmatic approach, by stages, to analysis the "unsorted" signal of cerebral activity, transmitted by telemetry. They use the selective properties of frequency filters associated with energy level thresholds, in order to obtain discrimination of the events appearing in the E.E.G. They emphasise the learning of objective reading, in its electrical composition, of the E.E.G. signal, and the need for good function of the telemeasure systems which transmit the information. The final stage involves a discriminator of paroxysmal electrical activity, programmable in its selective functions and in its association logic, essential for analysis by calculator, for statistical studies and in order to detect any electro-clinical correlation.

Electroencephalography↗