Search Results
Search for other papers by L J W Jack in
Google Scholar
PubMed
Search for other papers by S Kahl in
Google Scholar
PubMed
Search for other papers by D L St Germain in
Google Scholar
PubMed
Search for other papers by A V Capuco in
Google Scholar
PubMed
Abstract
Thyroxine 5′-deiodinase (5′D) catalyses deiodination of the prohormone thyroxine (T4) to the metabolically active hormone 3,5,3′-tri-iodothyronine (T3). Previously, it has been demonstrated that rat mammary gland expresses a 5′D with enzymatic properties equivalent to those of the type I enzyme (5′D-I) found in rat liver and kidney. Using complementary DNA (cDNA) for rat hepatic 5′D-I, we have examined expression of 5′D-I messenger RNA (mRNA) in liver, and mammary gland from virgin and lactating rats, and in seven other tissues from virgin rats. 5′D-I mRNA could not be detected in mammary gland either by Northern blotting or by the more sensitive technique of reverse transcribing mRNA and then amplifying the cDNA by polymerase chain reaction (RTPCR). Analysis of the seven tissues from virgin rats by RT-PCR showed 5′D-I amplicons in liver, kidney and thyroid. No amplicons were detected in adrenal gland, cardiac muscle, skeletal muscle or spleen. In addition, the effect of lactation intensity on circulating thyroid hormones, hepatic and mammary gland 5′D activity, and hepatic 5′D-I mRNA levels was examined. A strong inverse relationship was noted between increased lactation intensity (suckling burden) and circulating T4 and T3, hepatic 5′D-I activity and hepatic 5′D-I mRNA levels. Mammary gland 5′D activity was positively correlated to lactation intensity. The data presented strongly suggest that the 5′D activity expressed in lactating mammary gland is encoded by a mRNA different from the 5′D-I message found in rat liver, kidney and thyroid gland, and may help explain the differential regulation of 5′D-I activity in these organs during lactation. In addition, hepatic 5′D-I activity was found to be correlated with the concentration of 5′D-I mRNA, suggesting that regulation is pretranslational. Results are consistent with a previously suggested involvement of 5′D in establishing metabolic adaptations to support lactation.
Journal of Endocrinology (1994) 142, 205–215
Search for other papers by G Dai in
Google Scholar
PubMed
Search for other papers by D Wang in
Google Scholar
PubMed
Search for other papers by B Liu in
Google Scholar
PubMed
Search for other papers by JW Kasik in
Google Scholar
PubMed
Search for other papers by H Muller in
Google Scholar
PubMed
Search for other papers by RA White in
Google Scholar
PubMed
Search for other papers by GS Hummel in
Google Scholar
PubMed
Search for other papers by MJ Soares in
Google Scholar
PubMed
The prolactin (PRL) family consists of a collection of genes expressed in the uterus, placenta and anterior pituitary. These cytokines/hormones participate in the control of maternal-fetal adaptations to pregnancy. In this report, we establish the presence of three new members of the PRL family. Novel expressed sequence tags (ESTs) with homology to PRL were isolated from embryonic and placental cDNA libraries. The cDNAs were sequenced and compared with those of other members of the PRL family. The three new cDNAs were assigned to the PRL family on the basis of sequence similarities and were referred to as PRL-like protein-J (PLP-J), PRL-like protein-K (PLP-K) and PRL-like protein-M (PLP-M). Both rat and mouse PLP-J cDNAs were identified. Rat PLP-J cDNA encodes for a predicted 211 amino acid protein containing a 29 amino acid signal peptide and two putative N-linked glycosylation sites, whereas the mouse PLP-J cDNA encodes for a 212 amino acid protein containing a 29 amino acid signal peptide with a single N-linked glycosylation site. Rat and mouse PLP-J proteins share approximately 79% and 70% nucleotide and amino acid sequence identity, respectively. A full-length rat PLP-K cDNA and a partial tentative mouse PLP-K cDNA were identified. The rat PLP-K cDNA encodes for a predicted 228 amino acid protein containing a 31 amino acid signal peptide and one putative N-linked glycosylation site; the mouse PLP-M cDNA encodes for a predicted 228 amino acid protein containing a 28 amino acid signal peptide and one putative N-linked glycosylation site. Genes for PLP-J, PLP-K and PLP-M are situated at the Prl family locus on mouse chromosome 13. PLP-J was exclusively expressed in decidual tissue from both the mouse and rat. PLP-K was expressed in trophoblast cells of the chorioallantoic placenta and showed an apparent species difference. In the mouse, virtually all trophoblast lineages expressed PLP-K, whereas in the rat, PLP-K expression was restricted to the labyrinthine trophoblast cells. Mouse PLP-M expression was restricted to the junctional zone of the chorioallantoic placenta. In summary, we have identified three new members of the rodent PRL gene family that are expressed in uterine and placental structures. Future experimentation is needed to determine the specific roles of each of these ligands in the biology of pregnancy.
Search for other papers by Fung M-L in
Google Scholar
PubMed
Search for other papers by SY Lam in
Google Scholar
PubMed
Search for other papers by X Dong in
Google Scholar
PubMed
Search for other papers by Y Chen in
Google Scholar
PubMed
Search for other papers by PS Leung in
Google Scholar
PubMed
In the present study, the effects of postnatal hypoxemia on the AT1 angiotensin receptor-mediated activities in the rat carotid body were studied. Angiotensin II (Ang II) concentration-dependently increased the chemoreceptor afferent activity in the isolated carotid body. Single- or pauci-fiber recording of the sinus nerve revealed that the afferent response to Ang II was enhanced in the postnatally hypoxic carotid body. To determine whether the increased sensitivity to Ang II is mediated by changes in the functional expression of Ang II receptors in the carotid body chemoreceptors, cytosolic calcium ([Ca2+]i) was measured by spectrofluorimetry in fura-2 acetoxymethyl ester-loaded type I cells dissociated from carotid bodies. Ang II (25-100 nM) concentration-dependently increased [Ca2+]i in the type I cells. The proportion of clusters of type I cells responsive to Ang II was higher in the postnatally hypoxic group than in the normoxic control (89 vs 66%). In addition, the peak [Ca2+]i response to Ang II was enhanced 2- to 3-fold in the postnatally hypoxic group. The [Ca2+]i response to Ang II was abolished by pretreatment with losartan (1 microM), an AT1 receptor antagonist, but not by PD-123177 (1 microM), an AT(2) antagonist. Double-labeling immunohistochemistry confirmed that an enhanced immunoreactivity for AT1 receptor was co-localized to the lobules of type I cells in the hypoxic group. In addition, RT-PCR analysis of subtypes of AT1 receptors showed an up-regulation of AT1a but a down-regulation of AT1b receptors, indicating a differential regulation of the expression of AT1 receptor subtypes by postnatal hypoxia in the carotid body. These data suggest that postnatal hypoxemia is associated with an increased sensitivity of peripheral chemoreceptors in response to Ang II and an up-regulation of AT1a receptor-mediated [Ca2+]i activity of the chemoreceptors. This modulation may be important for adaptation of carotid body functions in the hypoxic ventilatory response and in electrolyte and water homeostasis during perinatal and postnatal hypoxia.
Search for other papers by C. E. Grosvenor in
Google Scholar
PubMed
Search for other papers by F. Mena in
Google Scholar
PubMed
Lactating rats were fed at a level equivalent to 75% of the daily food consumed by controls, which had food available ad libitum, from days 4–14 or from days 4–12 post partum. The underfed mothers lost about 10% of their initial weight whereas control mothers gained weight slightly during this time. The litters (six pups) of underfed mothers gained 20% less weight than those of controls but remained healthy. The milk obtained by the pups from six glands (the remaining six glands had been ligated on day 3) during a timed suckling, plus that subsequently obtained after oxytocin injections to the mother, totalled 7·4± 0·80 g in underfed and 15± 0·62 g in control mothers on day 14, and 6 ± 0·41 g in underfed compared with 8 ±0·50 g in control mothers on day 12. The pups of underfed mothers obtained a significantly greater percentage of the total milk after 10 (30 v. 6%), 15 (84 v. 32%) and 45 (100 v. 57%) min of suckling than did those of control mothers. In two trials for the milk ejection test, the litters of control and underfed mothers were exchanged. The pups of control mothers suckled by underfed mothers in both trials obtained a significantly greater percentage of the total milk (64%) in 15 min than did the pups of underfed mothers suckled by control mothers (25%).
Oxytocin-induced intramammary pressure (IMP) responses recorded under urethane anaesthesia achieved a greater amplitude in underfed than in control mothers in response to each dose (0·4, 0·8 and 1·6 mu.) of oxytocin administered intravenously. The average slope of the dose–response curve was 1·25 cm H2O/0·1 mu. oxytocin compared with 0·75cm H2O/0·1 mu. for fed mothers. The amplitude of the IMP in response to a 1·6 mu. dose of oxytocin also was greater in underfed mothers over a range of volumes of milk added incrementally to empty glands. The difference was most striking at low volumes of milk (0·2–0·6 ml) within the gland. The data from these experiments suggest the more rapid transfer of milk from mother to pups in underfed rats is due at least in part to adaptations within the mammary gland, possibly involving reductions in the sympathetic-mediated tone of mammary ducts.
Search for other papers by François van Herp in
Google Scholar
PubMed
Search for other papers by Nick H M van Bakel in
Google Scholar
PubMed
Search for other papers by Anton J M Coenen in
Google Scholar
PubMed
Search for other papers by Kjell Sergeant in
Google Scholar
PubMed
Search for other papers by Bart Devreese in
Google Scholar
PubMed
Search for other papers by Gerard J M Martens in
Google Scholar
PubMed
inactive and activated neuroendocrine cells. The model concerns a well-characterized physiological neuroendocrine reflex, namely skin color change as a result of adaptation to a changed background condition. By placing the animal on a black background, the
Search for other papers by Ian M Bird in
Google Scholar
PubMed
different physiologic states (see review by Boeldt et al . (2011) in this issue). Thus physiologic changes in eNOS activation may also be critically regulated at the level of sustained phase Ca 2 + signaling adaptation. Such adaptation occurs through
Search for other papers by David A Baltzegar in
Google Scholar
PubMed
Search for other papers by Benjamin J Reading in
Google Scholar
PubMed
Search for other papers by Jonathon D Douros in
Google Scholar
PubMed
Search for other papers by Russell J Borski in
Google Scholar
PubMed
for meeting the energy requirements of acute salinity adaptation ( Bashamohideen & Parvatheswararao 1972 , Chang et al . 2007 ). The full complement of hormones regulating energy mobilization and expenditure in fishes is unclear, but it may differ to
Search for other papers by Sergio Di Meo in
Google Scholar
PubMed
Search for other papers by Susanna Iossa in
Google Scholar
PubMed
Search for other papers by Paola Venditti in
Google Scholar
PubMed
able to induce major adaptations in skeletal muscle, which are dependent on the nature of the adaptive stimulus. Heavy resistance exercise, also referred to as strength training, typically consists of a small number of contractions (often fewer than
Center for Healthy Aging Research, Oregon State University, Corvallis, Oregon, USA
Search for other papers by Urszula T Iwaniec in
Google Scholar
PubMed
Center for Healthy Aging Research, Oregon State University, Corvallis, Oregon, USA
Search for other papers by Russell T Turner in
Google Scholar
PubMed
(2012) and Shapses and Sukumar (2012) . Mechanical loading and skeletal adaptation: mechanostat theory The skeleton serves multiple mechanical functions: (1) application of mechanical forces (e.g., jaws and fingers); (2) resisting mechanical
Search for other papers by Jay W Porter in
Google Scholar
PubMed
Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
Search for other papers by Joe L Rowles III in
Google Scholar
PubMed
Research Service-Harry S Truman Memorial VA Hospital, Columbia, Missouri, USA
University of Texas Southwestern Medical Center, Dallas, Texas, USA
Search for other papers by Justin A Fletcher in
Google Scholar
PubMed
Search for other papers by Terese M Zidon in
Google Scholar
PubMed
Search for other papers by Nathan C Winn in
Google Scholar
PubMed
Search for other papers by Leighton T McCabe in
Google Scholar
PubMed
University of Colorado Denver – Anschutz Medical Campus, Denver, Colorado, USA
Search for other papers by Young-Min Park in
Google Scholar
PubMed
Search for other papers by James W Perfield II in
Google Scholar
PubMed
Kansas City VA Medical Center, Kansas City, Missouri, USA
Search for other papers by John P Thyfault in
Google Scholar
PubMed
Research Service-Harry S Truman Memorial VA Hospital, Columbia, Missouri, USA
Search for other papers by R Scott Rector in
Google Scholar
PubMed
Department of Child Health, University of Missouri, Columbia, Missouri, USA
Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, USA
Search for other papers by Jaume Padilla in
Google Scholar
PubMed
Search for other papers by Victoria J Vieira-Potter in
Google Scholar
PubMed
adaptations are not completely understood. Fibroblast growth factor 21 (FGF21), a pleotropic endocrine hormone produced by several tissues, plays an important role in systemic glucose and lipid metabolism ( Kharitonenkov et al . 2005 , Zhang et al . 2008