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Biomedical subjects

J W Funder

Publications and source records attributed to J W Funder.

At least 343 records · Page 19Linked to original sources
PubMedDate not supplied

Co-expression of vasopressin with beta-endorphin and dynorphin in individual cells from the ovaries of Brattleboro and Long-Evans rats: immunocytochemical studies.

The distribution of arginine-vasopressin (AVP)-, oxytocin-, beta-endorphin (beta-EP)- and dynorphin-immunoreactive cells was examined by peroxidase-antiperoxidase (PAP) immunocytochemistry in the ovaries of Brattleboro and Long-Evans (LE) rats. The ovarian distribution of the peptide-immunoreactivity is indistinguishable between the two strains. AVP- and beta-EP-immunoreactivity is co-localized in the majority of luteal cells, and in some cells scattered in the interstitial tissue. Of the AVP/beta-EP-positive cells, 1-2% also contained immunoreactive (ir)-dynorphin. Some cells in the interstitium contained only ir-AVP (approximately 50%) or only ir-dynorphin (approximately 5%); in the corpora lutea, however, no luteal cells appeared to contain only one peptide. AVP-immunoreactivity is also present in theca cells surrounding secondary and large, antral follicles; ir-oxytocin was not observed in any ovarian cell type in the rat. These data suggest that most luteal, and some interstitial, cells in the ovary have the capacity to produce and store up to three different neuropeptides.

Animals↗
PubMedDate not supplied

N-acetylated endorphins in ovine anterior pituitary and neuro-intermediate lobe.

We have used an antiserum for immunohistochemistry and RIA/RP-HPLC which recognizes all fragments of N-acetylated endorphin (NacEP). In the rat neuro-intermediate lobe (N-IL), in addition to the N-acetylated forms of immunoreactive-beta-endorphin (ir-beta EP) already reported, we have demonstrated Nac beta EP as a minor component. In the sheep pituitary processing of beta EP is markedly different. In the anterior pituitary (AP), staining was indistinguishable with beta EP and NacEP antisera, in contrast with the rat where many fewer AP cells stained with the NacEP antiserum. Secondly, as in the rat, all N-IL cells stained with both antisera; on RP-HPLC, however, the major forms of NacEP in the sheep N-IL were Nac beta EP (approximately 40%), Nac beta EP (approximately 25%) and Nac beta EP (approximately 20%), with Nac beta EP (approximately 2%) as a minor component. A similar profile was seen on RP-HPLC of sheep AP. These data suggest that (1) patterns of processing in sheep AP are similar to those in N-IL, though the extent of acetylation is less and (2) in the sheep pituitary low molecular weight acetylated fragments predominate, in contrast with the rat.

Acetylation↗
PubMedDate not supplied

Characterization of immunoreactive AVP in the ovine hypothalamo-pituitary axis.

The aims of these studies were to determine the precise molecular nature of immunoreactive (IR-) vasopressin (AVP) in the ovine hypothalamo-pituitary axis and to examine a possible role for glucocorticoids in regulating both AVP processing and levels in this axis. The IR-AVP in extracts of paraventricular nucleus, median eminence, portal blood, and anterior and neurointermediate pituitary elutes as a single peak on two distinct HPLC solvent systems, suggesting that AVP is processed identically in these tissues. Identical profiles were also found in extracts from pituitaries and sheep subjected to chronic (10 days) glucocorticoid treatment, or hypothalamo-pituitary disconnection. The latter findings confirm that in sheep, like the rat, AVP is synthesized and processed in the anterior pituitary and is not sequestered from extrapituitary sources.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Immunoreactive beta-endorphin in sheep ovary.

Although the ovarian production of sex steroids is of obvious physiological importance, recent studies suggest that peptides such as oxytocin, relaxin and inhibin are also synthesized in the ovary. We report here the presence of immunoreactive (ir) beta-endorphin, ir-adrenocorticotropic hormone (ACTH) and presumptive high molecular weight forms of both in extracts of sheep ovary, consistent with ovarian production from a common precursor. Our findings suggest that beta-endorphin and ACTH are produced and secreted by the follicular cells, and that their production may be related to the oestrous cycle.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Immunoreactive arginine-vasopressin in Brattleboro rat ovary.

Homozygous (di/di) Brattleboro rats have normal hypothalamic levels of oxytocin and neurophysin I, but undetectable levels of neurophysin II and arginine-vasopressin (AVP). This defect has been presumed to be at the genomic or transcriptional level, as AVP messenger is reported to be drastically reduced, if not absent, from the hypothalamus of Brattleboro rats. Recent studies suggest de novo production of various neuropeptides in the mammalian gonad, including AVP. We report here the detection and localization of immunoreactive (ir) AVP in the luteal cells of adult homozygous Brattleboro rats, and the modulation of this ovarian ir-AVP by gonadotropins. These findings are thus consistent with a tissue-specific defect of AVP expression in the magnocellular neurones of the Brattleboro rat, and suggest that a comparable defect does not occur in the ovaries of such animals.

Animals↗
PubMedDate not supplied

Mineralocorticoid receptors in sheep kidney and parotid: studies in Na+ replete and Na+ deplete states.

1. As an adrenalectomized sheep becomes progressively more Na+ deplete, its salivary electrolyte secretion becomes increasingly sensitive to exogenous aldosterone administration. 2. Alteration in mineralocorticoid receptor affinity or concentration is a possible mechanism whereby this sensitivity could be expressed at a molecular level. 3. Bonding sites with a high affinity for aldosterone (Kd 37 degrees C approximately 5 x 10(-10) M) have been demonstrated in sheep kidney and parotid. 4. Renal binding sites were examined in detail, and shown to have affinity characteristics appropriate for mineralocorticoid receptors (aldosterone greater than deoxycorticosterone greater than dexamethasone greater than cortisol greater than progesterone greater than oestradiol greater than dihydrotestosterone). 5. No difference in mineralocoticoid receptor affinity or concentration could be shown between Na+ replete and Na+ deplete sheep, in either kidney or parotid gland. 6. Accordingly, the molecular mechanisms whereby parotid sensitivity is mediated remain as yet undefined.

Adrenalectomy↗
PubMedDate not supplied

Increased renal sensitivity to aldosterone in the rat: induction by a high potassium diet.

1. The renal response to aldosterone, measured by urinary sodium and potassium excretion, was determined in adrenalectomized rats that had been previously fed either a high potassium diet or a control diet. High K+ rats showed an enhanced response to aldosterone at all doses tested. 2. The induction of this enhanced response to aldosterone could be suppressed by a high sodium intake. It may also require the presence of the adrenal glands during the induction period, although interpretation of adrenalectomy experiments in the present study was made difficult by the effect of maintenance DOC therapy on the renal response to aldosterone. 3. The enhanced response could not be induced by a low sodium diet alone or by the administration of high doses of exogenous aldosterone. 4. No difference between high K+ and control rats could be detected in rat kidney mineralocorticoid receptors, assessed by both in vivo and in vitro binding of tritiated aldosterone. 5. The method of the induction, and the mechanism of the enhanced response remains to be defined.

Adrenalectomy↗
PubMedDate not supplied

Decreased cardiac beta-adrenoceptors in hypertensive rats.

1. beta-Adrenoceptors have been investigated in cardiac and renal cell membranes from hypertensive and normal rats. 2. The 125I-labelled beta-adrenoceptor antagonist 1-(4-iodophenoxy)-3-isopropylaminopropan-2-ol was used to measure directly the number and affinity of receptors. 3. Cardiac membranes from hypertensive rats had a lower concentration of beta-adrenoceptors than membranes from control normotensive animals, but the affinities of the receptors remained unchanged. Receptor concentration decreased by half and was similar in each of the three models of experimental hypertension investigated. 4. In contrast, kidney membranes from hypertensive animals had the same beta-adrenoceptor concentration and affinity as membranes from normotensive rats. 5. The decrease in cardiac beta-adrenoceptor concentration may reflect an increase in cardiac sympathetic drive in these experimental hypertensive models.

Animals↗
PubMedDate not supplied

Immunoreactive beta-endorphin levels in plasma and pituitary tissue from genetically hypertensive and normotensive rats.

1. Levels of immunoreactive beta-endorphin were measured in neurointermediate lobes, anterior lobes and plasma from the Japanese and New Zealand strains of genetically hypertensive rats and their normotensive controls. 2. No significant differences were observed in beta-endorphin between the hypertensive and normotensive rats of the New Zealand strain. 3. The hypertensive rats of the Japanese strain showed significantly higher levels of beta-endorphin in neurointermediate lobe and lower levels in plasma than their normotensive controls. 4. These results suggest that the differences in beta-endorphin levels in the Japanese strain reflect a genetic difference not necessarily related to elevated blood pressure.

Animals↗