One type of emotional behavior called restlessness occurs when the anteromedial hypothalamus is stimulated in cats. We examined the changes in the distribution and surface expression of adhesion molecules in leukocytes accompanied with restlessness. Mature female cats were used for this study. The cats were stimulated with 60 Hz sine wave train pulses (20–90 μA, 10 s in duration, at 5-min intervals) for 60 min. Samples of blood were collected from 30 min before stimulation up to several hours after the final stimulation. The number of granulocytes increased just after stimulation, while at the same time the expression of L-selectin decreased. On the other hand, the number of CD4+ and CD8+ T lymphocytes decreased at 1–2 h after the end of the stimulation, while the expression of L-selectin increased. In addition, the expression of LFA-1 and VLA-4 did not change. These data suggest that hypothalamically elicited restlessness is thus accompanied by a leukocyte distribution change, which might be mediated by changes in the expression of L-selectin on leukocytes. Plasma cortisol increased during stimulation in restlessness. However, during in vitro culture experiments, cortisol did not alter the expression of leukocyte L-selectin which thus indicated that cortisol does not directly affect the surface expression of L-selectin. These results thus suggest that hypothalamically induced restlessness is a useful stress model for psychoneuroimmunological studies.
The relationships of hypothalamically elicited emotional behaviors to their accompanying pathophysiological effects were examined as a model of how complex "emotional behaviors" may be related to fundamental psychosomatic disorders. Twenty-two unanesthetized adult cats were studied. EKG alterations and histological changes in the heart, stomach, adrenal glands, and thymus were related to the specific stereotypical emotional behaviors that could be elicited by hypothalamic stimulation in tamed subjects. Restlessness, threat, and searching-biting behaviors were evoked by electrical stimulation of the anteromedial, ventromedial, and lateral hypothalamus, respectively. The occurrence of cardiac arrhythmias, ST and/or T (ST-T) changes in the EKG, histological damage to myocardium, gastric erosion, and adrenal hyperplasia were generally observed in the restlessness and threat groups but not in the searching-biting group. The pathophysiological effects were similar in the restlessness and threat groups with no specific EKG change or organ effect attributable to either site of stimulation. Hypothalamically elicited restlessness or threat behaviors in cats are each associated with cardiac, gastric, and adrenal pathophysiologies.
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