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 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Both the capacity of CRF to release ACTH and the number of binding sites for CRF in the anterior pituitary decline during the final weeks of gestation in fetal sheep. The present study examined regulation of pituitary CRF receptor expression by the hypothalamic paraventricular nucleus (PVN) during late gestation in fetal sheep. Bilateral radiofrequency lesions of the PVN (PVN-Lx; n = 4) or sham lesions (SHAM; n = 5) were performed in fetal sheep at 118-122 days of gestational age (dGA). Pituitary glands from PVN-Lx and SHAM fetuses were collected at 139-142 dGA (term, approximately 148 dGA). Dual-label in situ hybridization was performed using a digoxigenin-labeled ovine POMC complementary RNA, together with a 35S-labeled ovine CRF type I (CRF1) receptor complementary RNA, to localize and quantify CRF1 receptor mRNA in POMC-hybridizing cells. Binding of [125I]-ovine CRF was also examined in the fetal pituitary of both PVN-Lx and SHAM fetuses using in situ autoradiography. The hybridization signal for the CRF1 receptor mRNA was primarily restricted to POMC-expressing cells in the anterior pituitary of both PVN-Lx and SHAM fetuses; no hybridization signal for the CRF1 receptor was observed in the neurointermediate lobe (NIL) in either group. The hybridization signal for CRF1 receptor mRNA in anterior pituitary corticotropes of PVN-Lx fetuses was significantly lower in both the inferior and superior regions of the anterior pituitary, compared with SHAM fetuses (P < 0.05). In the inferior region of the anterior pituitary, the percentage of POMC-hybridizing cells containing CRF1 receptor hybridization signal was significantly greater in PVN-Lx (90+/-7%; mean +/- SEM), compared with SHAM (67+/-6%; P < 0.05) fetuses. No differences in the percentage of POMC cells containing CRF1 receptor hybridization signal were observed in the superior region of the anterior pituitary between PVN-Lx (89+/-8%) and SHAM (87+/-9%). Binding of [125I]-ovine CRF (oCRF) was significantly greater in anterior pituitaries of PVN-Lx (140+/-19 mean arbitrary densitometry U +/- SEM), compared with SHAM (73+/-23; P < 0.05) fetuses. For both PVN-Lx and SHAM fetuses, there were no differences within group in [125I]-oCRF binding between the inferior and superior regions of the anterior pituitary. A weak, but significant (P < 0.05), autoradiographic signal for [125I]-oCRF binding was observed in the NIL of both SHAM and PVN-Lx fetal sheep. The level of [125I]-oCRF binding was significantly lower in the NIL, compared with anterior pituitary, for both SHAM (P < 0.01) and PVN-Lx fetuses. There were no differences in [125I]-oCRF binding in the NIL between SHAM and PVN-Lx fetal sheep. Our findings support a role for the PVN in regulating anterior pituitary CRF1 receptor expression in the late-gestation sheep fetus.
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PMID:Corticotropin-releasing factor receptor expression in the pituitary of fetal sheep after lesion of the hypothalamic paraventricular nucleus. 1046 3

We have investigated the effects of glucocorticoid manipulation on corticotrophin-releasing factor (CRF-41) in the neurointermediate lobe (NIL) and median eminence (ME) of the rat using a radioimmunoassay specific for CRF-41. CRF-41 content in the NIL (88+/-7 fmol, mean +/- SEM) was not significantly altered by administration of dexamethasone in drinking water for 12 days (67+/-9 fmol) or adrenalectomy for 12 days (96+/-17 fmol). The saline-stimulated increase in NIL CRF-41 content (154+/-24 fmol) was not affected by dexamethasone (152+/-24 fmol) or adrenalectomy (179+/-21 fmol). In contrast, the content of CRF-41 in the ME declined following dexamethasone treatment (1247+/-92 fmol to 864+/-26 fmol), or adrenalectomy (854+/-78 fmol). Our results provide further evidence that CRF-41 in the NIL and ME can be differentially regulated.
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PMID:Differential Effects of Glucocorticoids on Corticotrophin-Releasing Factor in the Rat Pituitary Neurointermediate Lobe and Median Eminence. 1210 9

The use of noninvasive measures of hypothalamic-pituitary-adrenal (HPA) axis function is of growing interest among preclinical and clinical investigators. This report describes a method for the repeated assessment of salivary free cortisol in awake, unrestrained squirrel monkeys (Saimiri sciureus) based on a saliva sampling technique previously developed for rhesus monkeys. Individually housed adult male squirrel monkeys were trained to chew on dental rope attached to a pole, from which saliva was extracted by centrifugation and analyzed for cortisol by radioimmunoassay (RIA). Eight of nine monkeys readily acquired the task, reliably providing adequate saliva samples for the assay. Salivary free cortisol levels were examined in these subjects under basal conditions and in response to two types of neuroendocrine challenge. Levels of salivary free cortisol showed relatively low intra- and interindividual variability, with mean individual morning levels ranging between 17.1 and 37.9 microg/dl. Squirrel monkeys demonstrated a consistent daily rhythm in salivary free cortisol ranging from a high of 27.4 +/- 5.2 microg/dl (mean +/- SEM) at 12 P.M. to a low of 7.5 +/- 1.6 microg/dl at 6 P.M. Intravenous (IV) challenges with 1 microg/kg ACTH, or 10 and 50 microg/kg CRF resulted in significant increases in salivary free cortisol. The described sampling technique provides a reliable and sensitive means for repeated measurement of HPA activity in unrestrained, awake squirrel monkeys. In addition, our findings illustrate several features of HPA system rhythmicity and reactivity using salivary cortisol instead of blood plasma or serum.
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PMID:Noninvasive technique for the repeated sampling of salivary free cortisol in awake, unrestrained squirrel monkeys. 1278 87

Glomerulonephritis (GN) is a major cause of CRF in Nigerians. Experimental evidence and clinical studies mostly in Caucasian subjects have associated hydrocarbon (HC) exposure with GN. We conducted a case-control study using a questionnaire-based quantitative HC exposure measurement to compare lifetime HC exposure levels between Nigerian patients with GN-induced CRF and matched healthy control subjects. Fifty consecutive patients with CRF from GN were compared with age and sex matched group of 45 healthy controls. A questionnaire designed to assess the sources, duration and intensity of HC exposure was used to compute an HC exposure score (HES) for each participant and the scores for the two groups were then compared. The HES was significantly higher in the patients (score +/- SEM) of 2307.5 +/- 698.8 vs. 53.4 +/- 16.5; p < 0.001. The HES was dichotomised by classifying all study subjects within the upper third of scores as a high-exposure sub-group. A significantly higher proportion of patients had high exposure (p<0.002). Logistic regression analysis excluded age and gender as confounding factors and determined a greater than four-fold risk of GN-induced CRF with high HC exposure (OR 4.3; 95% CI 1.7 - 11). In conclusion, our findings suggest that HC exposure is a significant risk factor for GN in Nigerians with CRF. Exposure limitation could help to reduce the burden of CRF in the country.
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PMID:Association of hydrocarbon exposure with glomerulonephritis in nigerians: a case control study. 1729 45


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