Environmental Effects on Animals Used in Biomedical Research

Abstract

Summary I. Reliability of the results of bio‐medical research clearly depends upon the animals used showing as standard responses as is possible. 2. The majority of animals used in this field are small, homoiothermic mammals which have sensitive and strong homeostatic mechanisms. If a change in ambient conditions is of sufficient magnitude to unbalance homeostasis, then the neuroendocrine system is stimulated so as to restore it, and this can interfere with the response to test conditions or agents. 3. The homeostatic effectors involved are diverse and can include both physiological and behavioural changes in the animal. These can affect metabolic rate, body temperature, activity, food consumption, hormone concentration, wake/sleep patterns, maturation, posture, lactation and many other bodily functions. Any of these changes is potentially capable of influencing experimental results. 4. The evidence presented shows how environmental factors may affect the outcome of experiments in the fields of animal behaviour, cancer research, immunology, pathology, pharmacology, psychology, reproduction, teratology and toxicology; particular attention is paid to the effects of ambient temperature, relative humidity, air movement and quality, light and sound. 5. While a constant, reproducible environment would be ideal, there is little possibility of controlling all the variables; nevertheless all investigators should minimize those environmental variables that have been shown to be important. 6. To enable other investigators to repeat experiments or carry out comparative studies, environmental conditions pertaining during an experiment should be adequately described in any publications.

Effects of long-term construction noise on health of adult female Wistar rats

“…The effects of sound on animal physiology and behavior depend not only on its intensity (or loudness), which is measured in decibels (dB), its frequency, which is measured in hertz (Hz), and its duration and pattern (including vibration potential), but also on the hearing ability of the animal species and strain, the age and physiological state of the animal at the time of exposure, to what sounds the animal has been exposed during its lifetime (noise exposure history of the animal) and to the predictability of the acoustic stimulus (Clough 1982, Gamble 1982, Voipio 1997, Turner et al 2005, Burn 2008. Meaningful sounds at relatively low-intensity levels can have a considerable impact on animal physiology and behaviour by engaging limbic structures and higher centers involved in determining context and meaning (Turner et al 2005).…”

Effects of Noise on Rabbit’s Blood

“…Such levels of noise can induce physiological and behavioral responses in laboratory rodents such as increased plasma corticosterone levels, reduction in body weight, decrease in gastric secretion, changes in immune response and tumor resistance, and a decrease in reproductive function. Behavioral responses include increases in total activity, grooming themselves and their cage-mates, and rearing onto their hind legs [7][8][9][10][11][12]. These changes are similar to those seen in rodents exposed to other stressful situations [13,14].…”

Effect of high wavelengths low intensity light during dark period on physical exercise performance, biochemical and haematological parameters of swimming rats

“…Despite the acute phase modulation on WBC caused by exercise, we have shown that the lighting environment was capable of promoting these increases in a chronic manner, as found in some diseases. Light is a very important environmental signal for circadian rhythm, promoting significant physiological and behavioural alterations (8,20,26). The high WBC counts in animals exposed to experimental illumination was probably generated by the stress of constant light during dark period, even through the light source was carefully determined.…”

“…Rat circadian rhythms are well characterised by high core body temperature (25, 36), spontaneous activity (21), food intake, heart rate and locomotion (25) during dark period, representing 62% of total sleep time in the daylight period (38). Circadian modulations of these parameters are mainly synchronised by environmental light for these mammals (8,20,26). During the wakefulness period these nocturnal laboratory animals are usually kept under total darkness, promoting an optimum environment for the rat but adverse conditions for visualisation-based assessments.…”

“…Circadian modulations of these parameters are mainly synchronised by environmental light for these mammals (8,20,26). During the wakefulness period these nocturnal laboratory animals are usually kept under total darkness, promoting an optimum environment for the rat but adverse conditions for visualisation-based assessments.…”