Potentiation of glucocorticoid release does not modify the long-term effects of a single exposure to immobilization stress

Rationale Previous work has shown that a single exposure of rats to a severe stressor (immobilization, IMO) results, days to weeks later, in a reduced response (desensitization) of the hypothalamic–pituitary–adrenal (HPA) axis to a second exposure to the same stressor.Objectives In the present work, we studied the influence of both length of exposure to IMO and circulating levels of corticosterone on the first day on the degree of desensitization of two sets of physiological variables: HPA hormones and food intake.Methods Rats were given SC saline or ACTH administration and then exposed to IMO for 0, 1 or 20 min. Seven days later, all rats were exposed to 20 min IMO. HPA response was followed on both experimental days by repeated blood sampling and food intake was measured on a 24-h basis.Results Both ACTH administration and IMO activates the HPA axis and IMO reduced food intake for several days. A single previous experience with IMO enhanced the post-IMO return of HPA hormones to basal levels on day 8 and reduced the degree of anorexia. The protective effect of previous IMO on food intake was independent of, whereas that on HPA activation was positively related to, the length of exposure on day 1. Concomitant ACTH administration on day 1 did not modify the observed effects.Conclusions Long-term protective effects of a single exposure to IMO are observed even with a brief exposure, but they are not potentiated by increasing corticosterone levels during the first exposure.     

Glucocorticoids are involved in the long-term effects of a single immobilization stress on the hypothalamic-pituitary-adrenal axis

We have previously observed that a single exposure to a severe stressor such as immobilization (IMO) induces long-lasting desensitization of the responsiveness of the hypothalamic–pituitary–adrenal (HPA) axis to the same stressor that enhances rather than dissipates with time (days). As this desensitization of the HPA axis was not observed in response to a novel stressor, we suggested this might be a particular type of learning linked to severe stressful situations. Taking into account the evidence that glucocorticoids are involved in learning and memory, the present study addresses the role of glucocorticoids in the induction of long-term effects of an acute exposure to IMO. Three different experimental approaches were used: (i) blockade of stress-induced corticosterone release by using adrenalectomized rats supplemented with a low dose of corticosterone in the drinking saline (ADX+B); (ii) blockade of corticosterone synthesis during the first exposure to IMO with the 11-β-hydroxylase inhibitor metyrapone (200 mg/kg); and (iii) administration of the glucocorticoid receptor antagonist RU486 (100 mg/kg). Previous exposure to IMO resulted in an enhanced post-stress recovery of the HPA response to the same stressor 1 week later. These long-term effects of IMO were blocked in ADX+B rats, were partially reduced in metyrapone-treated rats and only modestly affected by RU486 administration. These data suggest that glucocorticoids play a partial role in the induction of long-term effects of IMO on the HPA responsiveness to the same stressor, although the weak effect of RU486 suggests that non-classical corticosteroid receptors may be involved. The role of glucocorticoids in the expression of the phenomenon is suggested by the full blockade of the phenomenon in ADX+B rats, but further studies are needed. As blockade of corticosterone synthesis only partially blunted the long-term effect of IMO, it appears that full induction of the long-term effects of acute exposure to IMO on the HPA axis is only achieved by the concerted action of several endocrine (or neurochemical) factors.     

Cutaneous lymphomas showing prominent granulomatous component: clinicopathological features in a series of 16 cases

Background  The presence of a prominent granulomatous tissue reaction in skin biopsies from primary cutaneous or systemic malignant lymphomas with secondary cutaneous involvement is a rare but well-known phenomenon.
Objective  This paper aims to characterize and study a series of cutaneous lymphomas showing a prominent granulomatous component.
Patients and methods  The clinical, histopathological and evolutive features of granulomatous variants of mycosis fungoides (5 patients, 2 of them associating 'granulomatous slack skin' features), Sézary syndrome (1 patient), CD30⁺ cutaneous T-cell lymphoma (2 patients), CD4⁺ small/medium pleomorphic cutaneous T-cell lymphoma (1 patient), primary cutaneous B-cell lymphoma (3 patients) and peripheral T-cell lymphoma with secondary epithelioid granulomatous cutaneous involvement (4 patients) were reviewed.
Results  The observed features were clinically non-distinctive. Only those cases presenting with granulomatous slack skin features were clinically suspected (2 patients). Non-necrotizing granulomata (11 patients) and granuloma annulare-like (4 patients) were the most frequently observed histopathological patterns. In five cases, no diagnostic lymphomatous involvement was initially observed. From our series, no definite conclusions regarding prognosis could be established.
Conclusion  The diagnosis of cutaneous lymphoma may be difficult when a prominent cutaneous granulomatous inflammatory infiltrate obscures the true neoplastic nature of the condition. However, the presence of concomitant lymphoid atypia may help to suspect the diagnosis. In doubtful cases, the clinical evolution and the demonstration of a monoclonal lymphoid B- or T-cell population may lead to a definite diagnosis.

Conflicts of interest

None declared.     

Does 3-dimensional imaging of the third molar reduce the risk of experiencing inferior alveolar nerve injury owing to extraction?: A meta-analysis

Background

Clinicians generally use panoramic radiographic (PR) images to assess the proximity of the mandibular third molar to the inferior alveolar nerve (IAN). However, in cases in which a patient needs to undergo a third-molar extraction, many clinicians also assess computed tomographic (CT) images to prevent nerve damage.

Piezoelectric surgery versus conventional drilling for implant site preparation: a meta-analysis

Purpose

To answer the PICO question: “Among patients to whom an implant is placed, does the piezoelectric surgery (PS) compared to the conventional drilling (CS) achieve higher implant stability, increase surgical time or improve implant survival rate?”