Subregional differences in GABA receptor subunit expression in the rostral ventrolateral medulla of sedentary versus physically active rats.

Neurons in the rostral ventrolateral medulla (RVLM) regulate blood pressure through direct projections to spinal sympathetic preganglionic neurons. Only some RVLM neurons are active under resting conditions due to significant, tonic inhibition by gamma-aminobutyric acid (GABA). Withdrawal of GABA receptor-mediated inhibition of the RVLM increases sympathetic outflow and blood pressure substantially, providing a mechanism by which the RVLM could contribute chronically to cardiovascular disease (CVD).

Effects of a complex housing environment on heart rate and blood pressure of rats at rest and after stressful challenges.

Housing enrichment for rodents continues to be a discussion topic within the animal care community. The objective of this study was to determine the extent to which a complex housing environment affects heart rate, blood pressure, and activity of rats when undisturbed and after exposure to stressful challenges and whether autonomic controls of heart rate would be affected. Male and female Sprague-Dawley and Wistar rats with radiotelemetry transmitters were evaluated under nonenriched single-housing conditions and after acclimation to a complex environment of dim light and cohabitation with 3 conspecifics in large cages with hiding, food foraging, and nesting items.

Effects of cage enrichment on heart rate, blood pressure, and activity of female Sprague-Dawley and spontaneously hypertensive rats at rest and after acute challenges.

Here we sought to determine whether a nonsocial cage enrichment program, identical to one we previously used with male rats, was effective in reducing heart rate or systolic blood pressure (SBP) in female Sprague-Dawley rats and spontaneously hypertensive rats (SHR). Young adult rats, each instrumented with a radiotelemetry pressure transmitter, were housed individually under enriched or nonenriched conditions. Heart rate and SBP were monitored at 5- and 1-min intervals, respectively, when the rats were undisturbed or after several different types of experimental manipulations some of which are considered stressful.

Heart rates of male and female Sprague-Dawley and spontaneously hypertensive rats housed singly or in groups.

This study was conducted to confirm our previous reports that group housing lowered basal heart rate and various evoked heart-rate responses in Sprague-Dawley male and female rats and to extend these observations to spontaneously hypertensive rats. Heart rate data were collected by using radiotelemetry. Initially, group- and single-housed rats were evaluated in the same animal room at the same time.

Effect of housing rats in dim light or long nights on heart rate.

Housing laboratory animals under lighting conditions that more closely mimic the natural environment may improve their wellbeing. This study examined the effects of dim light or a long-night photocycle on resting heart rate (HR) of rats and their HR responses to acute procedures. Male and female Sprague-Dawley (SD) and spontaneously hypertensive (SHR) rats, instrumented with radiotelemetry transmitters and housed individually under a 12:12-h light:dark photocycle with 10 lx illumination (dim light) or under an 8:16-h light:dark photocycle with 200 lx illumination (long nights), were compared with control rats individually housed under a 12:12-h light:dark photocycle with 200 lx illumination.

Comparison of carbon dioxide, argon, and nitrogen for inducing unconsciousness or euthanasia of rats.

We compared CO(2), Ar, and N(2) for inducing unconsciousness and euthanasia of Sprague-Dawley rats. We determined time to unconsciousness and monitored heart rate (HR) and mean arterial blood pressure (MAP) by radiotelemetry to assess stress, recovery after exposure, and time of death. Unconsciousness (mean +/- standard error) occurred 24 +/- 3, 87 +/- 8, and 93 +/- 8 s after short-term exposure to CO(2), Ar, and N(2), respectively.

Stress-like cardiovascular responses to common procedures in male versus female spontaneously hypertensive rats.

We sought to determine the effects of gender on cardiovascular function of spontaneously hypertensive (SH) rats under basal conditions and after several common husbandry and experimental procedures. Heart rate (HR) and mean arterial blood pressure (MAP) were monitored by radiotelemetry during undisturbed periods in the morning, at night, and after acute and chronic procedures. When undisturbed in the morning and at night, female rats had significantly (P < 0.

Effects of a cage enrichment program on heart rate, blood pressure, and activity of male sprague-dawley and spontaneously hypertensive rats monitored by radiotelemetry.

To determine whether a nonsocial enrichment program affects cardiovascular responses of individually housed male Sprague-Dawley (SD) and spontaneously hypertensive (SH) rats under basal conditions and after potentially stressful procedures, we used radiotelemetry to record heart rate (HR), systolic blood pressure (SBP), and activity in the cage. Enrichment comprised a simulated burrow (Rodent Retreat), then a food foraging item ("rat cannoli") 2 days later, and a paper bag of bedding for shredding (Nestpak) after another 2 days. Data were collected under undisturbed conditions and before and after several acute and chronic manipulations mimicking common husbandry, experimental, and stressful procedures.

Selective adaptation of male rats to repeated social encounters and experimental manipulations.

The objective of the present study was to determine how rats adapt to repeated encounters with an unfamiliar male or group of males and to experimental manipulations. Male rats were instrumented with radiotelemetry transmitters to monitor heart rate (HR), mean arterial blood pressure (MAP), and movements in the home cage as indices of arousal and stress. Groups of eight singly housed rats were exposed in their home cages to encounters with an unfamiliar rat or a group of three rats of the same strain, age, and sex for a period of 18 h (1600 to 1000 h) on four consecutive days.

Recovery of male rats from major abdominal surgery after treatment with various analgesics.

The objective of this study was to compare the recovery of male rats after a major abdominal surgical procedure (the implantation of a radiotelemetry transmitter) when treated with buprenorphine, butorphanol, or ketoprofen and subcutaneous fluids (5% dextrose) or with subcutaneous fluids only. The parameters for assessing recovery were heart rate (HR), mean arterial blood pressure (MAP), home cage activity, food and water consumption, and body weight. HR, MAP, and activity were continuously monitored by radiotelemetry methods, food and water intakes were determined daily, and body weights were measured once or three times a week.

Does cage size affect heart rate and blood pressure of male rats at rest or after procedures that induce stress-like responses?

The objective of this study was to compare cardiovascular function and home-cage behavior of male Sprague-Dawley rats under resting conditions or after common husbandry and experimental procedures when the animals were housed with 3 other rats in cages with 920 or 1250 cm2 of floor space. Heart rate (HR), mean arterial blood pressure (MAP), and movement in the cage were monitored continuously by using radiotelemetry. The cardiovascular data are reported for a 1-h period in the morning before any human interventions, for the entire 12-h dark period, and before and after the following acute husbandry and experimental procedures: routine cage change; simulated cage change; restraint and subcutaneous (s.

Are "by-stander" female Sprague-Dawley rats affected by experimental procedures?

The objective of this study was to test the hypotheses that female rats are stressed by being in the same room as animals subjected to common husbandry and experimental procedures and that the level of stress is affected by housing density. Two commonly used indices of stress, heart rate (HR) and mean arterial blood pressure (MAP), were determined by using radiotelemetry for 2 h before and 3 h after rats witnessed the following procedures: decapitation, simulated decapitation, cage change, simulated cage change, restraint and subcutaneous injection, removal of rats to another room for injection, restraint and tail-vein injection, handling and weighing, and handling and vaginal lavage. In addition, home cage behaviors (sleeping, awake, moving, rearing, and grooming) were scored once each minute for 15 min before and 45 min after the procedures.

Stress-like responses to common procedures in individually and group-housed female rats.

The objective of this study was to assess the cardiovascular function and behavior of female Sprague-Dawley rats housed individually or with one or three cage mates under resting conditions and when subjected to common husbandry and experimental procedures and potentially stressful olfactory stimuli. Heart rate (HR) and mean arterial blood pressure (MAP) were assessed continuously by using radiotelemetry and are reported for the following periods: for 1 hour each day prior to any human interaction; for 12 h each day during the dark phase of the 12:12-h light: dark photoperiod; and for 2 h before and 3 h after acute husbandry and experimental procedures. Home-cage behaviors (sleeping, awake but not moving, moving, rearing, and grooming) were scored once each minute for 15 min before and 45 min after the acute procedures.

Does witnessing experimental procedures produce stress in male rats?

The objective of this study was to test the hypotheses that male rats are stressed by being in the same room as animals subjected to common husbandry and experimental procedures and that the level of stress is affected by housing density. Two commonly used indices of stress, heart rate (HR) and mean arterial blood pressure (MAP), were determined by using radiotelemetry for 2 h before and 3 h after rats witnessed the following procedures: decapitation, decapitation and necropsy, cage change, restraint and subcutaneous injection, and restraint and tail-vein injection. In addition, home cage behaviors (sleeping, awake, moving, rearing, and grooming) were scored once each minute for 15 min before and 45 min after the procedures.

Stress-like responses to common procedures in male rats housed alone or with other rats.

The objective of this study was to assess the cardiovascular function and behavior of male Sprague-Dawley rats housed individually or with one or three cagemates during resting conditions and when subjected to common husbandry and experimental procedures and potentially stressful olfactory stimuli. Heart rate (HR), mean arterial blood pressure (MAP), and movement in the cage were collected by using radiotelemetry for 24 h on an experiment-free day and for 2 h before and 3 h after the following acute procedures: cage change, restraint and subcutaneous injection, restraint and tail-vein injection, exposure to the odor of urine and feces from stressed rats, and exposure to the odor of dried rat blood. Home cage behaviors (sleeping, awake, moving, rearing, and grooming) were scored once each minute for 15 min before and 45 min after the acute procedures.