6-Hydroxydopamine Lesion of Ventral Tegmental Area Dopaminergic Cell Bodies does not Impair Neuroendocrine Responses to Environmental Stimuli.
Abstract To evaluate the influence of dopamine neurons in neuroendocrine responses to environmental stimulations, rats received bilateral injections of the neurotoxin 6-hydroxydopamine in the ventral tegmental area. Six weeks after the lesion, forebrain areas lost up to 88% of their dopamine content, and the areas innervated by the noradrenergic bundle, which passes through the ventral tegmental area, were also depleted of noradrenaline. Despite these profound changes of catecholamine content, we show that the responses of major neuroendocrine systems to environmental stimuli were not modified. Basal levels of circulating adrenocorticotropin, corticosterone, prolactin and catecholamines, as well as their increase by novel environment exposure, handling and/or electric footshock, were not modified by the lesion. These results favor the hypothesis that the effect of dopamine depletion is more on behavioral response initiation and/or performance than on the cognitive functions or emotional processes. They also question the importance of the ventral noradrenergic bundle in the activation of the hypothalamo-pituitary-adrenal axis by stressful stimuli.
Rivet
J M
JM
Laboratoire de Psychobiologie des Comportements Adaptatifs, INSERM Unité 259-INRA, Rue Camille St Saëns, 33077 Bordeaux, France.
Stinus
L
L
Moal
M
M
Mormède
P
P