EFFECT OF ENVIRONMENTAL STRESSORS ON TIME-COURSE, VARIABILITY AND FORM OF SELF-GROOMING IN THE RAT - HANDLING, SOCIAL CONTACT, DEFEAT, NOVELTY, RESTRAINT AND FUR MOISTENING
Amm. Vanerp et al., EFFECT OF ENVIRONMENTAL STRESSORS ON TIME-COURSE, VARIABILITY AND FORM OF SELF-GROOMING IN THE RAT - HANDLING, SOCIAL CONTACT, DEFEAT, NOVELTY, RESTRAINT AND FUR MOISTENING, Behavioural brain research, 65(1), 1994, pp. 47-55
Grooming is often related to dearousal following stressors. Interestin
gly, electrical and chemical stimulation of the paraventricular nucleu
s of the hypothalamus (PVH), at levels that are known to activate the
hypothalamus-pituitary adrenal axis (HPA), also elicits grooming. At t
he level of the PVH, the neuroendocrine stress response is apparently
still linked to the behavioural response to stressors. However the pre
cise nature of this relation is not fully understood. Here we report o
n grooming in rats following exposure to different stressors which are
known to activate the HPA axis. Stressors such as handling, restraint
, novelty, encounters with aggressive or non-aggressive conspecifics,
or moistening the fur, change the amount and time course of grooming u
pon return in the home cage, as compared with controls that are just h
andled. However the amount of grooming is not directly related to the
strength of the stressor. Defeated intruders groom less upon return in
their home cage. Novelty and non-aggressive encounters with conspecif
ics reduce the variation in the amount of grooming between rats. The t
ime course of grooming over the 20-min observation period also differs
between treatments. Following restraint, or exposure to non-aggressiv
e conspecifics, grooming first increases and then decreases. Moistened
rats immediately start grooming which subsequently decreases. Rats us
ed as intruders in the territory of another rat maintain a constant lo
w level of grooming. Rats placed in a novel cage steadily increase gro
oming during the 20-min observation period. These results suggest that
grooming cannot be simply understood as an immediate response necessa
ry to reduce arousal following stressors. Following exposure to a stre
ssor, grooming rather seems temporary suppressed. If grooming has a re
storative function, it is a delayed function, which is not directly re
lated to the strength of the stressor.