A. Haemisch et K. Gartner, EFFECTS OF CAGE ENRICHMENT ON TERRITORIAL AGGRESSION AND STRESS PHYSIOLOGY IN MALE LABORATORY MICE, Acta Physiologica Scandinavica, 161, 1997, pp. 73-76
The activation of different neuroendocrine subsystems depends on the i
ndividual perception and coping with the challenging situation. the fo
rmulation of these relations by J.P. Henry represents a most useful co
ncept also for the assessment of welfare consequences of particular ca
ging variables. We investigated effects of cage enrichment on behaviou
r and neuroendocrine activations of male laboratory mice. Mice in enri
ched cages behaved more aggresive, lacked stable dominance hierarchies
and exhibited neuroendocrine alterations depending on their individua
l social position. Subdominant passive mice were characterized by an a
ugmented adrenal capacity to synthesize epinephrine despite low activi
ties of the tyrosine hydroxylase. Dominant mice showed elevated circul
ating corticosterone concentrations despite high tyrosine hydroxylase-
activities. Findings showed a dissociation of neurosympathetic and adr
enomedullary components in subdominant passive mice and a simultaneous
activation of sympathetic adrenomedullary and hypothalamo-adrenocorit
cal components in dominant mice. Within the conceptual framework of th
e Henry model this would suggest different deteriorations of welfare i
n dominant and subdominant passive mice. In the situation of intensifi
ed aggression in the enriched cages the increased epinephrine synthesi
s in subdominant mice relfect their more frequent receipt of attacks a
nd the elevated corticosterone secretion in dominant mice reflect thei
r hindered ability to control the dominant position.