PubMed · 13565044
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S M BLUEFARB. 1958. Pemphigus.. https://pubmed.ncbi.nlm.nih.gov/13565044/
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We have previously observed that a single exposure to immobilization (IMO), a severe stressor, caused long-term (days to weeks) desensitization of the response of the hypothalamic-pituitary-adrenal (HPA) axis to the homotypic stressor, with no changes in behavioral reactivity to novel environments. In contrast, other laboratories have reported that a single exposure to footshock induced a long-term sensitization of both HPA and behavioral responses to novel environments. To test whether these apparent discrepancies can be explained by the use of different stressors or different strains of rats, we studied in the present work the long-term effects of a single exposure to two different stressors (footshock or IMO) in two different strains of rats (Sprague-Dawley from Iffa-Credo and Wistar rats from Harlan). We found that both strains showed desensitization of the HPA response to the same (homotypic) stressor after a previous exposure to either shock or IMO. The long-term effects were higher after IMO than shock. No major changes in behavior in two novel environments (circular corridor, CC and elevated plus-maze, EPM) were observed after a single exposure to shock or IMO in neither strain, despite the fact that shocked rats showed a conditioned freezing response to the shock boxes. The present results demonstrate that long-term stress-induced desensitization of the HPA axis is a reliable phenomenon that can be observed with different stressors and strains. However, only behavioral changes related to shock-induced conditioned fear were found, which suggests that so far poorly characterized factors are determining the long-term behavioral consequences of a single exposure to stress.
Behavioral and neuroendocrine differences may be postulated in hirsute subjects since central effects of gonadal steroids are well established. We conducted a controlled clinical study with 25 consecutive young hirsute participants compared with 20 consecutive controls. Neuropsychological evaluation included the Minnesota Multiphasic Personality Inventory (MMPI) and the Edinburgh Inventory of Manual Preference (EIMP). Neuroendocrine reactivity was assessed by the adrenocorticotropic hormone (ACTH) and cortisol responses to corticotropin releasing hormone (CRH). Hirsute participants presented a flattened personality profile with lower neurotic triad scores--146 +/- 20 versus 166 +/- 28. Left-hand preference was more common in hirsute participants--4/21 versus 0/20. Decreased ACTH [area under the curve (AUC)--36 +/-2 8 vs. 72 +/- 63 pg/ml h] and cortisol (AUC--18 +/- 4 vs. 25 +/- 10 microg/dl h) responses to CRH were found in the hirsute group. In the hirsute group, higher manual preference scores were associated with lower ACTH responses to CRH, while the opposite association was found in the control group. In the hirsute group, the hyporeactive hypothalamic-pituitary-adrenal (HPA) axis was associated with lower behavior-deviant scores, while in the control group, the hyporeactive HPA axis was associated with more psychopathology. We conclude that personality and HPA axis reactivity are different in hirsute female participants when compared with controls, with a trend for differences regarding handedness. Personality and handedness are differently associated with HPA reactivity. Distinctive features in hirsute participants are probably established very early during ontogenic development.
The present study was aimed to test the hypothesis that behavioral sensitization to intermittent administration of morphine is accompanied by sensitization of adrenocorticotropine (ACTH) and corticosterone responses and with signs of hyperactivity of the hypothalamic-pituitary-adrenocortical function in mice. Male mice were injected subcutaneously with 40 mg/kg morphine or saline every 72 h for 16 days (in total, six injections were performed) and the effects were compared to those after single drug injection. Hormones were investigated 60 min after the last (6th) morphine or saline injection, i.e. 3 days after the 5th injection of intermittent treatments. Locomotor sensitization was confirmed in a separate series. ACTH levels in response to the last morphine injection of the repeated dosage regimen were found to be lower compared to those in acutely morphine-treated mice. Morphine administration was followed by increases in plasma corticosterone, but no significant differences between the acutely and repeatedly treated groups were observed. The body weight of morphine-treated mice showed a characteristic pattern with decreases measured the day after morphine administration. No statistically significant differences in adrenal and thymus weights were found. In conclusion, behavioral sensitization to morphine in mice is accompanied by a blunted rather than an enhanced ACTH response to drug injection. Unchanged levels of plasma corticosterone demonstrate an absence of tolerance and possible involvement of ACTH unrelated mechanisms needs further verification. Intermittent administration of morphine for 2 weeks failed to induce marked signs of glucocorticoid overexposure.