Biomedical subjects
Publications and source records attributed to V M Wiegant.
A review of the literature emphasizes that cyclic nucleotides play a key role in regulation of cell growth, differentiation and metabolism in diverse tissues and, in addition, are closely involved in neural tissue function. The role of cAMP as a second messenger is discussed.
Intraventricular administration of an access of ACTH 4-10 does not interfere with the excessive grooming behavior of rats, elicited by intraventricular administration of [D-Phe7] ACTH 4-10. In an avoidance extinction paradigm, the two ACTH analogs have opposite effects. ACTH 4-10 counteracts the facilitation of extinction seen after [D-Phe7] ACTH 4-10, only under conditions that treatment with ACTH 4-10 alone results in retardation of that extinction. The data are discussed in terms of a multiple interaction of these peptides with brain function.
Individual differences in behavioral and physiological response patterns to stress may contribute to vulnerability for stress-related illnesses such as functional gastrointestinal disorders. Animal models could give clues about specific individual determinants of intestinal reactivity to stress and stress-induced sensitization. Rats fitted with permanent electrodes on the proximal colon were exposed to a single session of foot shocks (10 x 6 s in 15 min, preshocked) or no shocks (control). Two weeks later, the preshocked group showed a significantly greater colonic spike burst response to a novel shock-prod stressor in the home cage than controls. The increase in burst frequency was positively correlated with the duration of active burying of the threatening prod in both experimental groups, but not with other behavioral components. Basal colonic burst frequency at rest was negatively correlated with the increase in burst frequency due to shock-prod stress in both groups, but the degree of sensitization in preshocked rats vs. controls was of similar magnitude in rats with low and high basal colonic burst frequency. The results indicate that colonic responsivity to stress is related to both basal motility status and individual coping strategies.
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The aims of the two studies were to investigate the relationship between emotions and immune responses in an experimental setting by inducing social fear and to broaden our understanding of bodily reactions by examining both cardiovascular and hormonal responses. Seventy-nine healthy subjects were confronted with a situation in which relatively strong social fear was induced in the laboratory. Social fear was induced by having to prepare and give an oral presentation in front of an audience. Thirty additional healthy subjects formed a control group; they followed exactly the same procedure, but, instead of the "public speaking situation," they were subjected to a nondemanding task of the same duration. The results indicate that public speaking evoked fear as shown by both elevated feelings of tenseness and negative bodily sensations. Moreover, the data clearly show enhanced cardiovascular activity, elevated plasma hormone levels, and changes in immunological parameters (natural killer cell number and T helper/inducer cells). The control group reported significantly less feelings of tenseness and negative bodily sensations and showed a decrease in cortisol, prolactin, and beta-endorphin levels. Although some variation on immune responses was present, no variation on cardiovascular activity occurred in the control group during the experiment. The results show that there is indeed a relationship between emotion and immune responses. In addition, the data collected on body responses point to a direct mediating effect of sympathetic-adrenal medulla activity and an indirect mediating effect of hypothalamo-pituitary-adrenal axis activity.