Corticotropic and serotonergic responses to acute stress with/without prior exercise training in different rat strains
Acta Physiologica Scandinavica. 2000-03-01; 168(3): 421-430
DOI: 10.1046/j.1365-201X.2000.00683.x
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Martin CL(1), Duclos M, Aguerre S, Mormede P, Manier G, Chaouloff F.
Author information:
(1)Laboratoire de Physiologie de l’Exercice Musculaire et du Sport, Université
Bordeaux II, 146 rue Léo Saignat, Bordeaux Cedex, France.
The ability to cope with exercise training depends both on environmental and
genetic background; however, whether the genetic status may affect (i) the
hormonal status of trained subjects and, (ii) its responses to a heterotypic
stressor is unknown. Herein, we have used Spontaneously Hypertensive Rats (SHR)
and Lewis rats, that differ with regard to their psychoneuroendocrine profiles,
to study the influences of an 8-week training programme and/or a 1-h
immobilization stress on plasma adrenocorticotropin (ACTH) and corticosterone
levels. In addition, brain serotonin metabolism was also measured as an index of
neurochemical reactivity to stress. The amplitude of immobilization-elicited
increases in ACTH levels which differed with the rat strain (Lewis > SHR), was
amplified by prior training; besides, training decreased the strain difference in
basal corticosterone (SHR > Lewis) and affected corticosterone response to
immobilization in a strain-dependent manner. Thus, immobilization, which
increased corticosterone levels in sedentary Lewis but not in SHRs, did not
reveal interstrain differences in trained rats. Taken with the observation of a
stimulatory effect of training on adrenal weights in SHRs, but not in Lewis, it
is concluded that the effects of training on the corticotropic axis depend on the
genetic profile of the individual. Lastly, training amplified the response of
midbrain (but not striatum or hippocampus) serotonin metabolism to immobilization
in a strain-independent manner although the levels of serotonin precursor, namely
tryptophan, varied with training and immobilization in a strain-dependent manner.
This study shows that some neuroendocrine and neurochemical effects of training
undergo interindividual variability.