[Salivary gland disorder: consider IgG4-related disease]. / Speekselklierafwijking: denk aan IgG4-gerelateerde ziekte.

A 73-year-old man was presented with painless, bilateral swelling of the submandibular salivary glands and unilateral swelling of the parotid gland on the right side, and complaints of dry mouth. A parotid biopsy was taken and a serologic exam was carried out, resulting in the diagnosis of IgG4-related disease. IgG4-related disease is a rare systemic disorder that can cause symptoms in the head and neck region. Usually there are complaints of bilateral, painless swelling of the submandibular, parotid and/or lacrimal glands, with or without complaints of dryness of the mouth and eyes.

Glycogen synthase 1 targeting reveals a metabolic vulnerability in triple-negative breast cancer.

BACKGROUND: Hypoxia-induced glycogen turnover is implicated in cancer proliferation and therapy resistance. Triple-negative breast cancers (TNBCs), characterized by a hypoxic tumor microenvironment, respond poorly to therapy. We studied the expression of glycogen synthase 1 (GYS1), the key regulator of glycogenesis, and other glycogen-related enzymes in primary tumors of patients with breast cancer and evaluated the impact of GYS1 downregulation in preclinical models. METHODS: mRNA expression of GYS1 and other glycogen-related enzymes in primary breast tumors and the correlation with patient survival were studied in the METABRIC dataset (n = 1904). Immunohistochemical staining of GYS1 and glycogen was performed on a tissue microarray of primary breast cancers (n = 337). In four breast cancer cell lines and a mouse xenograft model of triple-negative breast cancer, GYS1 was downregulated using small-interfering or stably expressed short-hairpin RNAs to study the effect of downregulation on breast cancer cell proliferation, glycogen content and sensitivity to various metabolically targeted drugs. RESULTS: High GYS1 mRNA expression was associated with poor patient overall survival (HR 1.20, P = 0.009), especially in the TNBC subgroup (HR 1.52, P = 0.014). Immunohistochemical GYS1 expression in primary breast tumors was highest in TNBCs (median H-score 80, IQR 53-121) and other Ki67-high tumors (median H-score 85, IQR 57-124) (P < 0.0001). Knockdown of GYS1 impaired proliferation of breast cancer cells, depleted glycogen stores and delayed growth of MDA-MB-231 xenografts. Knockdown of GYS1 made breast cancer cells more vulnerable to inhibition of mitochondrial proteostasis. CONCLUSIONS: Our findings highlight GYS1 as potential therapeutic target in breast cancer, especially in TNBC and other highly proliferative subsets.

Fluorescence grid analysis for the evaluation of piecemeal surgery in sinonasal inverted papilloma: a proof-of-concept study.

PURPOSE: Local recurrence occurs in ~ 19% of sinonasal inverted papilloma (SNIP) surgeries and is strongly associated with incomplete resection. During surgery, it is technically challenging to visualize and resect all SNIP tissue in this anatomically complex area. Proteins that are overexpressed in SNIP, such as vascular endothelial growth factor (VEGF), may serve as a target for fluorescence molecular imaging to guide surgical removal of SNIP. A proof-of-concept study was performed to investigate if the VEGF-targeted near-infrared fluorescent tracer bevacizumab-800CW specifically localizes in SNIP and whether it could be used as a clinical tool to guide SNIP surgery. METHODS: In five patients diagnosed with SNIP, 10 mg of bevacizumab-800CW was intravenously administered 3 days prior to surgery. Fluorescence molecular imaging was performed in vivo during surgery and ex vivo during the processing of the surgical specimen. Fluorescence signals were correlated with final histopathology and VEGF-A immunohistochemistry. We introduced a fluorescence grid analysis to assess the fluorescence signal in individual tissue fragments, due to the nature of the surgical procedure (i.e., piecemeal resection) allowing the detection of small SNIP residues and location of the tracer ex vivo. RESULTS: In all patients, fluorescence signal was detected in vivo during endoscopic SNIP surgery. Using ex vivo fluorescence grid analysis, we were able to correlate bevacizumab-800CW fluorescence of individual tissue fragments with final histopathology. Fluorescence grid analysis showed substantial variability in mean fluorescence intensity (FImean), with SNIP tissue showing a median FImean of 77.54 (IQR 50.47-112.30) compared to 35.99 (IQR 21.48-57.81) in uninvolved tissue (p < 0.0001), although the diagnostic ability was limited with an area under the curve of 0.78. CONCLUSIONS: A fluorescence grid analysis could serve as a valid method to evaluate fluorescence molecular imaging in piecemeal surgeries. As such, although substantial differences were observed in fluorescence intensities, VEGF-A may not be the ideal target for SNIP surgery. TRIAL REGISTRATION: NCT03925285.

Exploiting metabolic acidosis in solid cancers using a tumor-agnostic pH-activatable nanoprobe for fluorescence-guided surgery.

Cancer cell metabolism leads to a uniquely acidic microenvironment in solid tumors, but exploiting the labile extracellular pH differences between cancer and normal tissues for clinical use has been challenging. Here we describe the clinical translation of ONM-100, a nanoparticle-based fluorescent imaging agent. This is comprised of an ultra-pH sensitive amphiphilic polymer, conjugated with indocyanine green, which rapidly and irreversibly dissociates to fluoresce in the acidic extracellular tumor microenvironment due to the mechanism of nanoscale macromolecular cooperativity. Primary outcomes were safety, pharmacokinetics and imaging feasilibity of ONM-100. Secondary outcomes were to determine a range of safe doses of ONM-100 for intra-operative imaging using commonly used fluorescence camera systems. In this study (Netherlands National Trial Register #7085), we report that ONM-100 was well tolerated, and four solid tumor types could be visualized both in- and ex vivo in thirty subjects. ONM-100 enables detection of tumor-positive resection margins in 9/9 subjects and four additional otherwise missed occult lesions. Consequently, this pH-activatable optical imaging agent may be clinically beneficial in differentiating previously unexploitable narrow physiologic differences.

GlycA, a novel pro-inflammatory glycoprotein biomarker is associated with mortality: results from the PREVEND study and meta-analysis.

BACKGROUND: Chronic diseases are associated with an inflammatory response. We determined the association of two inflammatory markers, GlycA and high-sensitivity C-reactive protein (hsCRP), with overall and cause-specific mortality in a cohort of men and women. METHODS: Cox regression analyses were used to examine associations of GlycA and hsCRP with all-cause, cancer and cardiovascular mortality in 5526 subjects (PREVEND cohort; average follow-up 12.6 years). RESULTS: GlycA was associated with all-cause mortality (n = 838), independent of clinical risk factors and hsCRP (hazard ratio 1.43 [95% confidence interval (CI): 1.09-1.87] for top versus bottom quartiles). For hsCRP, the association with all-cause mortality was nonsignificant after adjustment for GlycA. GlycA and hsCRP were associated with cancer mortality in men (n = 248), but not in women (n = 132). Neither GlycA nor hsCRP was independently associated with cardiovascular mortality (n = 201). In a meta-analysis of seven population-based studies, including 8153 deaths, the pooled multivariable-adjusted relative risk of GlycA for all-cause mortality was 1.74 (95% CI: 1.40-2.17) for top versus bottom quartiles. The association of GlycA with all-cause mortality was somewhat stronger than that of hsCRP. GlycA and hsCRP were not independently associated with cardiovascular mortality. The associations of GlycA and hsCRP with cancer mortality were present in men, but not in women. CONCLUSIONS: GlycA is significantly associated with all-cause mortality. GlycA and hsCRP were each not independently associated with cardiovascular mortality. The association of GlycA and hsCRP with cancer mortality appears to be driven by men.

89Zr-trastuzumab PET supports clinical decision making in breast cancer patients, when HER2 status cannot be determined by standard work up.

BACKGROUND: Up-to-date information on human epidermal growth factor receptor 2 (HER2) status in breast cancer (BC) is important, as expression can vary during the course of the disease, necessitating anti-HER2 therapy adjustments. Repeat biopsies, however, are not always possible. In this feasibility trial we assessed whether 89Zr-trastuzumab PET could support diagnostic understanding and aid clinical decision making, when HER2 status could not be determined by standard work up. Additionally, HER2 status on circulating tumour cells (CTCs) was assessed. PATIENTS AND METHODS: 89Zr-trastuzumab PET was performed in patients if disease HER2 status remained unclear after standard work up (bone scan, 18F-FDG PET, CT and if feasible a biopsy). PET result and central pathologic revision of available tumour biopsies were reported to the referring physician. CTC HER2 status prior to PET was evaluated afterwards and therefore not reported. Diagnostic understanding and treatment decision questionnaires were completed by the referring physicians before, directly after and ≥ 3 months after 89Zr-trastuzumab PET. RESULTS: Twenty patients were enrolled: 8 with two primary cancers (HER2-positive and HER2-negative BC or BC and non-BC), 7 with metastases inaccessible for biopsy, 4 with prior HER2-positive and -negative metastases and 1 with primary BC with equivocal HER2 status. 89Zr-trastuzumab PET was positive in 12 patients, negative in 7 and equivocal in 1 patient. In 15/20 patients, 89Zr-trastuzumab PET supported treatment decision. The scan altered treatment of 8 patients, increased physicians' confidence without affecting treatment in 10, and improved physicians' disease understanding in 18 patients. In 10/20 patients CTCs were detected; 6/10 showed HER2 expression. CTC HER2 status was not correlated to 89Zr-trastuzumab PET result or treatment decision. CONCLUSION: 89Zr-trastuzumab PET supports clinical decision making when HER2 status cannot be determined by standard work up. The impact of CTC HER2 status needs to be further explored.

High sensitivity and negative predictive value of sentinel lymph node biopsy in a retrospective early stage oral cavity cancer cohort in the Northern Netherlands.

OBJECTIVES: In cT1-2N0, oral squamous cell carcinoma (OSCC) occult metastases are detected in 23%-37% of cases. Sentinel lymph node biopsy (SLNB) was introduced in head and neck cancer as a minimally invasive alternative for an elective neck dissection in neck staging. Meta-analyses of SLNB accuracy show heterogeneity in the existing studies for reference standards, imaging techniques and pathological examination. The aim of this study was to assess the sensitivity and negative predictive value (NPV) of the SLNB in detecting occult metastases in cT1-2N0 OSCC in a well-defined cohort. DESIGN: Retrospective study. The SLNB procedure consisted of lymphoscintigraphy, SPECT/CT-scanning and gamma probe detection. Routine follow-up was the reference standard for the SLNB negative neck. Histopathological examination of sentinel lymph nodes (SLN) consisted of step serial sectioning, haematoxylin-eosin and cytokeratin AE1/3 staining. SETTING: Two comprehensive oncology centres. PARTICIPANTS: A total of 91 consecutive patients with primary cT1-2N0 OSCC treated by primary resection and neck staging by SLNB procedure between 2008 and 2016. MAIN OUTCOME MEASURES: Sensitivity and negative predictive value. RESULTS: In all cases, SLNs were harvested. A total of 25 (27%) patients had tumour-positive SLNs. The median follow-up was 32 months (range 2-104). Four patients were diagnosed with an isolated regional recurrence in the SLNB negative neck side resulting in an 85% sensitivity and a 94% NPV. CONCLUSION: In our cohort, the SLNB detected occult metastases in early OSCC with 85% sensitivity and 94% NPV. This supports that SLNB is a reliable procedure for surgical staging of the neck in case of oral cT1-2N0 SCC.

RAB25 expression is epigenetically downregulated in oral and oropharyngeal squamous cell carcinoma with lymph node metastasis.

Oral and oropharyngeal squamous cell carcinoma (OOSCC) have a low survival rate, mainly due to metastasis to the regional lymph nodes. For optimal treatment of these metastases, a neck dissection is required; however, inaccurate detection methods results in under- and over-treatment. New DNA prognostic methylation biomarkers might improve lymph node metastases detection. To identify epigenetically regulated genes associated with lymph node metastases, genome-wide methylation analysis was performed on 6 OOSCC with (pN+) and 6 OOSCC without (pN0) lymph node metastases and combined with a gene expression signature predictive for pN+ status in OOSCC. Selected genes were validated using an independent OOSCC cohort by immunohistochemistry and pyrosequencing, and on data retrieved from The Cancer Genome Atlas. A two-step statistical selection of differentially methylated sequences revealed 14 genes with increased methylation status and mRNA downregulation in pN+ OOSCC. RAB25, a known tumor suppressor gene, was the highest-ranking gene in the discovery set. In the validation sets, both RAB25 mRNA (P = 0.015) and protein levels (P = 0.012) were lower in pN+ OOSCC. RAB25 mRNA levels were negatively correlated with RAB25 methylation levels (P < 0.001) but RAB25 protein expression was not. Our data revealed that promoter methylation is a mechanism resulting in downregulation of RAB25 expression in pN+ OOSCC and decreased expression is associated with lymph node metastasis. Detection of RAB25 methylation might contribute to lymph node metastasis diagnosis and serve as a potential new therapeutic target in OOSCC.

Detection of HPV-associated oropharyngeal tumours in a 16-year cohort: more than meets the eye.

BACKGROUND: Accurate assessment of the prevalence of the human papilloma virus (HPV) in oropharyngeal tumours (OpSCC) is important because HPV-positive OpSCC are consistently associated with an improved overall survival. Recently, an algorithm has become available that reliably detects clinically relevant HPV in tumour tissue, however, no complete cohorts have been tested. The aim was to determine the prevalence of active high-risk HPV infection in a complete cohort of OpSCC collected over a 16-year period. METHODS: Using a triple algorithm of p16 immunohistochemistry, HPV-BRISH and HPV-PCR, we assessed the prevalence of active HPV infection in all OpSCC diagnosed in our hospital from 1997 to 2012 (n=193) and a random selection of 200 oral tumours (OSCC). RESULTS: Forty-seven OpSCC (24%) were HPVGP PCR-positive; 42 cases were HPV16+, 1 HPV18+, 3 HPV33+ and 1 HPV35+. Brightfield in situ hybridisation did not identify additional HPV-positive cases. Human papilloma virus-associated tumour proportion increased from 13% (1997-2004) to 30% (2005-2012). Human papilloma virus-positivity was an independent predictor for longer disease-specific survival (HR=0.22; 95%CI:0.10-0.47). Only one OSCC was HPV+. CONCLUSIONS: In our cohort, the incidence of HPV-associated OpSCC is low but increasing rapidly. The strict detection algorithm, analysis of disease-specific survival and the complete cohort, including palliatively treated patients, may influence the reported prevalence and prognostic value of HPV in OpSCC.

Targeting breast cancer through its microenvironment: current status of preclinical and clinical research in finding relevant targets.

It is increasingly evident that not only breast cancer cells, but also the tissue embedding these cells: the tumor microenvironment, plays an important role in tumor progression, metastasis formation and treatment sensitivity. This review focuses on the current knowledge of processes by which the microenvironment affects breast cancer, including formation of the metastatic niche, metabolic stimulation, stimulation of tumor cell migration, immune modulation, angiogenesis and matrix remodeling. The number of drugs targeting key factors in these processes is expanding, and the available clinical data is increasing. Therefore current strategies for intervention and prediction of treatment response are outlined. At present, targeting the formation of the metastatic niche and metabolic stimulation by the breast cancer microenvironment, are already showing clinical efficacy. Intervening in the stimulation of tumor cell migration and immune modulation by the microenvironment upcoming fields of great research interest. In contrast, targeting microenvironmental angiogenesis or matrix remodeling appears to be of limited clinical relevance in breast cancer treatment so far. Further research is warranted to optimize intervention strategies and develop predictive tests for the relevance of targeting involved factors within the microenvironment in order to optimally personalize breast cancer treatment.

Microarray methods to identify factors determining breast cancer progression: potentials, limitations, and challenges.

65-80% of the patients with breast cancer might not benefit from the adjuvant therapy they receive based on 'classical' markers used for the selection for adjuvant therapy. Therefore it is necessary to develop new markers that are able to tailor treatment for an individual patient. A number of microarray methods have been developed in recent years to accommodate this search for new factors that determine breast cancer progression. We give an overview of the most commonly used microarray methods to identify tumour progression markers (oligo- or cDNA arrays, CGH arrays, PCR arrays, and tissue microarrays). Their applications will be illustrated using the most influential examples from literature. The potentials, limitations and the related statistical analyses of each method are discussed. We conclude that microarray studies have led to an increase in the understanding of the complexity and diversity of breast carcinoma and have provided clinical relevant subgroups of breast cancer that may benefit from patient tailored treatment. Still, more extensive external validation and long-term follow-up will be necessary before such assays can be implemented into routine clinical practice. Most likely, these novel prognostic indicators will be complementary to the already available classical prognostic factors.

The expression pattern of MUC1 (EMA) is related to tumour characteristics and clinical outcome in 'pure' ductal carcinoma in situ of the breast.

AIMS: To classify MUC1 according to five predefined expression patterns in ductal carcinoma in situ (DCIS) and related clinicopathological parameters, coexpression of other biological markers and prognosis. METHODS AND RESULTS: With a manual tissue arrayer, 92% (n = 80) of the 87 DCIS samples were successfully targeted. Immunohistochemistry was carried out for MUC1, oestrogen receptor (ER), progesterone receptor (PR), Her2/Neu, p53 and cyclin D1. Entire membrane expression was related to Her2/neu negativity (P =0.042). Apical membrane expression was associated with low grade (P = 0.027), Her2/neu negativity (P = 0.014) and PR positivity (P = 0.005). Focal cytoplasmic expression was related to high grade (P = 0.006). Diffuse cytoplasmic expression was associated with high grade (P = 0.004), large tumour size (P = 0.046), Her2/neu positivity (P =0.042) and cyclin D1 positivity (P = 0.002). On the basis of these analyses the four patterns were reclassified as membranous or cytoplasmic expression. On multivariate analysis, cytoplasmic MUC1 expression (hazard ratio 8.5, 95% confidence interval 1.0, 73.0; P = 0.04) was the only independent predictor of local recurrence. CONCLUSIONS: Four patterns of MUC1 expression are recognized in DCIS that suggest a relationship to functional differentiation and can be simplified into two types that are clinically relevant and could therefore be helpful in the distinction between different subgroups of DCIS.

The expression pattern of MUC1 (EMA) is related to tumour characteristics and clinical outcome of invasive ductal breast carcinoma.

AIMS: To clarify MUC1 patterns in invasive ductal breast carcinoma and to relate them to clinicopathological parameters, coexpression of other biological markers and prognosis. METHODS AND RESULTS: Samples from 243 consecutive patients with primary ductal carcinoma were incorporated into tissue microarrays (TMAs). Slides were stained for MUC1, oestrogen receptor (ER), progesterone receptor (PR), Her2/neu, p53 and cyclin D1. Apical membrane MUC1 expression was associated with smaller tumours (P = 0.001), lower tumour grades (P < 0.001), PR positivity (P = 0.003) and increased overall survival (OS; P = 0.030). Diffuse cytoplasmic MUC1 expression was associated with cyclin D1 positivity (P = 0.009) and increased relapse-free survival (RFS; P = 0.034). Negativity for MUC1 was associated with ER negativity (P = 0.004), PR negativity (P = 0.001) and cyclin D1 negativity (P = 0.009). In stepwise multivariate analysis MUC1 negativity was an independent predictor of both RFS [hazard ratio (HR) 3.5, 95% confidence interval (CI) 1.5, 8.5; P = 0.005] and OS (HR 14.7, 95% CI 4.9, 44.1; P < 0.001). CONCLUSIONS: The expression pattern of MUC1 in invasive ductal breast carcinoma is related to tumour characteristics and clinical outcome. In addition, negative MUC1 expression is an independent risk factor for poor RFS and OS, besides 'classical' prognostic indicators.

Axillary recurrence after sentinel lymph node biopsy.

UNLABELLED: Sentinel lymph node biopsy (SLNB) without further axillary dissection in patients with sentinel node-negative breast carcinoma appears to be a safe procedure to ensure locoregional control. During a median follow-up of 35 months the false-negative rate was 1% in our study population of 185 patients. BACKGROUND: The objective of this prospective study is to provide data on follow-up of patients with primary operable breast carcinoma staged with SLNB without axillary lymph node dissection (ALND) if the sentinel lymph nodes (SLNs) were tumour-negative. METHODS: One hundred and eighty-five patients were enrolled. Preoperative dynamic and static lymphoscintigraphy were performed; both a vital blue dye and a gamma detection probe were used intraoperatively. Patients with tumour-positive SLNs received completion ALND or if no SLNs could be identified. All patients were monitored according to regional follow-up protocols. RESULTS: The SLNs were identified in 179 out of the 185 patients. In 73 patients the SLNs were tumour-positive and in 106 patients tumour-negative. The median follow-up was 35 months (range 17-59). In one SLN-negative patient an axillary recurrence occurred 26 months after the SLNB (false-negative rate: 1%). CONCLUSIONS: SLNB without ALND appears to be a safe procedure to ensure locoregional control in SLN-negative breast carcinoma, if carried out by an experienced team.

Enhanced sensitivity of postsynaptic serotonin-1A receptors in rats and mice with high trait aggression.

Individual differences in aggressive behaviour have been linked to variability in central serotonergic activity, both in humans and animals. A previous experiment in mice, selectively bred for high or low levels of aggression, showed an up-regulation of postsynaptic serotonin-1A (5-HT(1A)) receptors, both in receptor binding and in mRNA levels, in the aggressive line [Brain Res 736 (1996) 338]. The aim of this experiment was to study whether similar differences in 5-HT(1A) receptors exist in individuals from a random-bred rat strain, varying in aggressiveness. In addition, because little is known about the functional consequences of these receptor differences, a response mediated via postsynaptic 5-HT(1A) receptors (i.e., hypothermia) was studied both in the selection lines of mice and in the randomly bred rats. The difference in receptor binding, as demonstrated in mice previously, could not be shown in rats. However, both in rats and mice, the hypothermic response to the 5-HT(1A) agonist alnespirone was larger in aggressive individuals. So, in the rat strain as well as in the mouse lines, there is, to a greater or lesser extent, an enhanced sensitivity of postsynaptic 5-HT(1A) receptors in aggressive individuals. This could be a compensatory up-regulation induced by a lower basal 5-HT neurotransmission, which is in agreement with the serotonin deficiency hypothesis of aggression.

The effect of parity and environmental restriction on behavioural and physiological responses of pre-parturient pigs.

There is increasing evidence that restriction of pre-parturient behaviour in pigs is stress-inducing, characterised by an elevation in hypothalamic-pituitary-adrenal (HPA) activity in gilts. To determine whether pigs adapt to behavioural restriction, through modification of nest-building behaviour, we studied pre-parturient pigs in either farrowing crates (no bedding, n=7) or straw-bedded pens (n=7) in their first (gilts) and second (sows) parity, with physiological measurements being taken in the second parity. Observations and blood sampling were carried out during the pre-parturient phase. Crated pigs changed posture more often than penned pigs (F(1,12)=7.06, P<0.05), with the number of posture changes reducing across parities in both environments. The reduction in posture changing was more apparent in the crated sows which may indicate that attempted nest-building behaviour of sows with prior experience of farrowing crates is less fragmented. The crated pigs spent a greater proportion of time sitting across both parities (F(1,12)=9.4, P<0.01), and spent less time manipulating available substrates (F(1,12)=10.67, P<0.05). There was a tendency for penned pigs to spend a greater proportion of time standing (F(1,12)=3.77, P=0.076) with peak nesting behaviour occurring earlier in relation to parturition than in crated pigs. In addition penned sows performed more floor-directed behaviour than penned gilts, and at an earlier stage in relation to parturition. However, crated sows also performed peak nest-building earlier than crated gilts. Plasma cortisol profiles indicated elevated HPA activity in crated sows during the pre-parturient period (F(42,303)=1.43, P<0.05) suggesting increased physiological stress, however, the difference between crated and penned sows was less than that previously seen in gilts. The increased range of pre-parturient behaviours seen in the penned sows suggests that experience may result in an 'improvement' in their nest-building behaviour: earlier preparation of the nest site and then subsequent manipulation of substrates. The crated sows appeared to show some behavioural adaptation to the crate environment; earlier peak in floor directed behaviour and total substrate directed behaviour, reduced posture changing. In conclusion the nest-building behaviour of pigs is modified over parities with adaptation to the behavioural restrictions imposed by the farrowing crate. However, this adaptation, through prior experience, does not completely reduce the elevation in HPA activity previously reported in pre-parturient crated gilts.

Coping styles in animals: current status in behavior and stress-physiology.

This paper summarizes the current views on coping styles as a useful concept in understanding individual adaptive capacity and vulnerability to stress-related disease. Studies in feral populations indicate the existence of a proactive and a reactive coping style. These coping styles seem to play a role in the population ecology of the species. Despite domestication, genetic selection and inbreeding, the same coping styles can, to some extent, also be observed in laboratory and farm animals. Coping styles are characterized by consistent behavioral and neuroendocrine characteristics, some of which seem to be causally linked to each other. Evidence is accumulating that the two coping styles might explain a differential vulnerability to stress mediated disease due to the differential adaptive value of the two coping styles and the accompanying neuroendocrine differentiation.

Long-lasting deficient dexamethasone suppression of hypothalamic-pituitary-adrenocortical activation following peripheral CRF challenge in socially defeated rats.

The present study focuses on the long-term changes in the regulation of the hypothalamic-pituitary-adrenocortical (HPA) axis following two short-lasting episodes of intensive stress in the rat stress model of social defeat and the possible similarities with HPA functioning in human affective disorders. Male Wistar rats experienced social defeats on 2 consecutive days by an aggressive male conspecific. The long-term effect of these defeats on resting and ovine corticotropin-releasing factor (oCRF; intravenous (i.v.) 0. 5 microg/kg) induced levels of plasma ACTH and corticosterone (CORT) were measured 1 and 3 weeks later. In a second experiment the glucocorticoid feedback regulation of HPA function was tested in a combined dexamethasone (DEX)/CRF test (DEX; 25 microg/kg s.c., 90 min before oCRF injection, 0.5 microg/kg). The oCRF challenges were performed between 11.00 and 13.00 h (about three hours after start of the light phase). One week after defeat the ACTH response to CRF was significantly enhanced in defeated rats as compared to controls. Three weeks after defeat the ACTH response was back to control levels. The increased ACTH response 1 week after the stressor was not reflected in higher CORT levels. Neither were baseline ACTH and CORT levels affected by the prior stress exposure. DEX pretreatment inhibited pituitary adrenocortical activity, reflected both in reduced baseline and response values of ACTH and CORT. The ACTH response to CRF following DEX administration was significantly higher in defeated rats as compared to controls both at one and three weeks after defeat. A reduced DEX suppression of baseline secretion of ACTH appeared 3 weeks after defeat. The same tendency was apparent in response and baseline values of CORT. The differences in CORT between socially stressed and control treated rats, however, did not reach significance. The possible role of changes in glucocorticoid-(GR) and mineralocorticoid receptor (MR) binding in the altered regulation of HPA activity following defeat were studied in brain and pituitary of male Wistar rats 1 and 3 weeks after defeat. One week after defeat GR-binding decreased in hippocampus and hypothalamus. No changes were observed in GR-binding in the pituitary nor in MR-binding in any of the regions analysed. Three weeks after defeat GR-binding recovered in hippocampus and hypothalamus but at this time MR-binding in hippocampal tissue was seriously decreased. In a fourth experiment vasopressin (AVP) and CRF stores in the external zone of the median eminence (ZEME) were measured by quantitative immunocytochemistry one and three weeks after defeat and compared with controls. Social defeat failed to induce a change in the immunocytochemical stores of AVP or CRF. The present findings show that in rats short-lasting stressors like defeat induce long-lasting, temporal dynamic changes in the regulation of the HPA axis. Since these changes in time are reflected in GRs and MRs in different brain areas an altered corticosteroid receptor binding might play an important role in the affected HPA activity following defeat.