Developmental pattern of TRH-degrading activity and TRH content in rat pancreas

1984 ◽  
Vol 106 (1) ◽  
pp. 102-108 ◽  
Author(s):  
Sonia Aratan-Spire ◽  
Bryan Wolf ◽  
Paul Czernichow
Keyword(s):  
Adult Life ◽  
Postnatal Period ◽  
Neonatal Rat ◽  
Adult Rats ◽  
Thyrotrophin Releasing Hormone ◽  
Developmental Patterns ◽  
Rat Pancreas ◽  
Adult Rat ◽  
Gastro Intestinal Tract ◽  
Peak Value

Abstract. Thyrotrophin-releasing hormone (TRH), like several other neuropeptides, has been detected in the gastro-intestinal tract of adult rats. More recently, elevated concentrations of TRH have been found in the neonatal rat pancreas. This study was undertaken to evaluate pancreatic TRH degrading activity (TRH-DA) in infant rats from birth until adult life. Pancreatic TRH of age-matched rats was also measured by radioimmunoassay. TRH-DA was present in normal adult rat pancreas; though absent at birth and in the early postnatal period up to day 7, this activity was detected during the remainder of the developmental period. TRH content (pg ± sem per pancreas) was 1139 ± 88 on day 1, reached a peak value of 7360 ± 758 at day 2 and then decreased steadily to adult level. TRH-DA has been found to be present at birth in hypothalamus and liver but not in plasma. The developmental patterns of TRH-DA in plasma and in pancreas were parallel and seem to be thyroid hormone dependent. The absence of TRH-DA in the neonatal pancreas may also be related to the high TRH concentrations detected in this organ during the neonatal period.

scholarly journals Prolactin inhibition at the end of lactation programs for a central hypothyroidism in adult rat

2008 ◽  
Vol 198 (2) ◽  
pp. 331-337 ◽  
Author(s):  
Isabela Teixeira Bonomo ◽  
Patrícia Cristina Lisboa ◽  
Magna Cottini Fonseca Passos ◽  
Simone Bezerra Alves ◽  
Adelina Martha Reis ◽  
...  
Keyword(s):  
Body Weight ◽  
Adult Life ◽  
Iodide Uptake ◽  
Adult Rats ◽  
Central Hypothyroidism ◽  
Adult Rat ◽  
Glycerophosphate Dehydrogenase ◽  
Pituitary Thyroid Axis ◽  
Serum Tsh

Malnutrition during lactation is associated with hypoprolactinemia and failure in milk production. Adult rats whose mothers were malnourished presented higher body weight and serum tri-iodothyronine (T3). Maternal hypoprolactinemia at the end of lactation caused higher body weight in adult life, suggesting an association between maternal prolactin (PRL) level and programming of the offspring's adult body weight. Here, we studied the consequences of the maternal PRL inhibition at the end of lactation by bromocriptine (BRO) injection, a dopaminergic agonist, upon serum TSH and thyroid hormones, thyroid iodide uptake, liver mitochondrial α-glycerophosphate dehydrogenase (mGPD), liver and pituitary de-iodinase activities (D1 and/or D2), and in vitro post-TRH TSH release in the adult offspring. Wistar lactating rats were divided into BRO – injected with 1 mg/twice a day, daily for the last 3 days of lactation, and C – control, saline-injected with the same frequency. At 180 days of age, the offspring were injected with 125I i.p. and after 2 h, they were killed. Adult animals whose mothers were treated with BRO at the end of lactation presented lower serum TSH (−51%), T3 (−23%), and thyroxine (−21%), lower thyroid 125I uptake (−41%), liver mGPD (−55%), and pituitary D2 (−51%) activities, without changes in the in vitro post-TRH TSH release. We show that maternal PRL suppression at the end of lactation programs a hypometabolic state in adulthood, in part due to a thyroid hypofunction, caused by a central hypothyroidism, probably due to decreased TRH secretion. We suggest that PRL during lactation can regulate the hypothalamus–pituitary–thyroid axis and programs its function.

Growth hormone (GH) autofeedback action in the neonatal rat: involvement of GH-releasing hormone and somatostatin

1990 ◽  
Vol 124 (2) ◽  
pp. 199-205 ◽  
Author(s):  
S. G. Cella ◽  
V. De Gennaro Colonna ◽  
V. Locatelli ◽  
V. Moiraghi ◽  
S. Loche ◽  
...  
Keyword(s):  
Body Weight ◽  
Inhibitory Effect ◽  
Postnatal Period ◽  
Neonatal Rat ◽  
Gh Treatment ◽  
Adult Rats ◽  
Releasing Hormone ◽  
Term Administration

ABSTRACT It is known that in adult rats, GH by itself and by promoting secretion of the somatomedins acts at the level of the hypothalamus to trigger release of somatostatin and decrease output of GH-releasing hormone (GHRH), thereby inhibiting further secretion of GH. To assess whether these mechanisms are already operative in the early postnatal period, we have evaluated the effect of short-term administration of GH in 10-day-old rats. Twice-daily s.c. administration of 25 μg human GH/rat, from days 5 to 9 of life, significantly reduced pituitary content of GH, decreased hypothalamic levels of GHRH mRNA and abolished the in-vivo GH response to a challenge dose of GHRH (20 ng/100 g body weight, s.c.). GHRH (20 ng/100 g body weight, twice daily, s.c.) given concomitantly with the GH treatment, completely counteracted the inhibitory effect of the latter on pituitary content of GH and restored to normal the in-vivo GH response to the GHRH challenge. These data indicate that impaired secretion of GHRH is involved in the inhibitory effect elicited by GH treatment in infant rats. However, concomitant involvement of hypothalamic somatostatin as a result of GH treatment cannot be ruled out. In fact, pituitaries from rats pretreated with GH responded in the same manner as pituitaries from control rats to the GHRH challenge in vitro. Journal of Endocrinology (1990) 124, 199–205

Characterization of Mitotic Neurons Derived From Adult Rat Hypothalamus and Brain Stem

2002 ◽  
Vol 87 (2) ◽  
pp. 1076-1085 ◽  
Author(s):  
Jenafer Evans ◽  
Colin Sumners ◽  
Jennifer Moore ◽  
Matthew J. Huentelman ◽  
Jie Deng ◽  
...  
Keyword(s):  
Tissue Culture ◽  
Membrane Potential ◽  
Brain Stem ◽  
Adult Brain ◽  
Neonatal Rat ◽  
Peak Current Density ◽  
Adult Rats ◽  
Peak Current ◽  
Rat Hypothalamus ◽  
Adult Rat

Embryonic or neonatal rat neurons retain plasticity and are readily grown in tissue culture, but neurons of the adult brain were thought to be terminally differentiated and therefore difficult to culture. Recent studies, however, suggest that it may be possible to culture differentiated neurons from the hippocampus of adult rats. We modified these procedures to grow differentiated neurons from adult rat hypothalamus and brain stem. At day 7 in tissue culture and beyond, the predominant cell types in hypothalamic and brain stem cultures had a stellate morphology and could be subdivided into two distinct groups, one of which stained with antibodies to the immature neuron marker α-internexin, while the other stained with the astrocyte marker GFAP. The α-internexin positive cells were mitotic and grew to form a characteristic two-dimensional cellular network. These α-internexin positive cells coimmunostained for the neuronal markers MAP2, type III β-tubulin, and tau, and also bound tetanus toxin, but were negative for the oligodendrocyte marker GalC and also for the neurofilament triplet proteins NF-L, NF-M, and NF-H, markers of more mature neurons. Patch-clamp analysis of these α-internexin positive cells revealed small Ca2+ currents with a peak current of −0.5 ± 0.1 pA/pF at a membrane potential of −20 mV ( n = 5) and half-maximal activation at −30 mV ( n = 5). Na+ currents with a peak current density of −154.5 ± 49.8 pA/pF at a membrane potential of −15 mV ( n = 5) were also present. We also show that these cells can be frozen and regrown in tissue culture and that they can be efficiently infected by viral vectors. These cells therefore have the immunological and electrophysiological properties of immature mitotic neurons and should be useful in a variety of future studies of neuronal differentiation and function.

scholarly journals Comparative analysis of neonatal and adult rat carotid body responses to chronic intermittent hypoxia

2008 ◽  
Vol 104 (5) ◽  
pp. 1287-1294 ◽  
Author(s):  
Anita Pawar ◽  
Ying-Jie Peng ◽  
Frank J. Jacono ◽  
Nanduri R. Prabhakar
Keyword(s):  
Carotid Body ◽  
Intermittent Hypoxia ◽  
Ex Vivo ◽  
Adult Life ◽  
Sensory Response ◽  
Chronic Intermittent Hypoxia ◽  
Adult Rats ◽  
Adult Rat ◽  
Carotid Bodies

Previous studies suggest that carotid body responses to long-term changes in environmental oxygen differ between neonates and adults. In the present study we tested the hypothesis that the effects of chronic intermittent hypoxia (CIH) on the carotid body differ between neonates and adult rats. Experiments were performed on neonatal (1–10 days) and adult (6–8 wk) males exposed either to CIH (9 episodes/h; 8 h/day) or to normoxia. Sensory activity was recorded from ex vivo carotid bodies. CIH augmented the hypoxic sensory response (HSR) in both groups. The magnitude of CIH-evoked hypoxic sensitization was significantly greater in neonates than in adults. Seventy-two episodes of CIH were sufficient to evoke hypoxic sensitization in neonates, whereas as many as 720 CIH episodes were required in adults, suggesting that neonatal carotid bodies are more sensitive to CIH than adult carotid bodies. CIH-induced hypoxic sensitization was reversed in adult rats after reexposure to 10 days of normoxia, whereas the effects of neonatal CIH persisted into adult life (2 mo). Acute intermittent hypoxia (IH) evoked sensory long-term facilitation of the carotid body activity (sensory LTF, i.e., increased baseline neural activity following acute IH) in CIH-exposed adults but not in neonates. The effects of CIH were associated with hyperplasia of glomus cells in neonatal but not in adult carotid bodies. These observations demonstrate that responses to CIH differ between neonates and adults with regard to the magnitude of sensitization of HSR, susceptibility to CIH, induction of sensory LTF, reversibility of the responses, and morphological remodeling of the chemoreceptor tissue.

scholarly journals Intercellular Communication within the Rat Anterior Pituitary Gland. XV. Properties of Spontaneous and LHRH-Induced Ca2+ Transients in the Transitional Zone of the Rat Anterior Pituitary in Situ

Endocrinology ◽  
2013 ◽  
Vol 154 (1) ◽  
pp. 400-409 ◽  
Author(s):  
Kazuki Hattori ◽  
Nobuyuki Shirasawa ◽  
Hikaru Suzuki ◽  
Takanobu Otsuka ◽  
Ikuo Wada ◽  
...  
Keyword(s):  
Anterior Pituitary ◽  
Cyclopiazonic Acid ◽  
Transitional Zone ◽  
Neonatal Rat ◽  
Neonatal Rats ◽  
Adult Rats ◽  
Adult Rat ◽  
Voltage Dependent

In the transitional zone of the rat anterior pituitary, spontaneous and LHRH-induced Ca2+ dynamics were visualized using fluo-4 fluorescence Ca2+ imaging. A majority of cells exhibited spontaneous Ca2+ transients, while small populations of cells remained quiescent. Approximately 70% of spontaneously active cells generated fast, oscillatory Ca2+ transients that were inhibited by cyclopiazonic acid (10 μm) but not nicardipine (1 μm), suggesting that Ca2+ handling by endoplasmic reticulum, but not Ca2+ influx through voltage-dependent L-type Ca2+ channels, plays a fundamental role in their generation. In the adult rat anterior pituitary, LHRH (100 μg/ml) caused a transient increase in the Ca2+ level in a majority of preparations taken from the morning group rats killed between 0930 h and 1030 h. However, the second application of LHRH invariably failed to elevate Ca2+ levels, suggesting that the long-lasting refractoriness to LHRH stimulation was developed upon the first challenge of LHRH. In contrast, LHRH had no effect in most preparations taken from the afternoon group rats euthanized between 1200 h and 1400 h. In the neonatal rat anterior pituitary, LHRH caused a suppression of spontaneous Ca2+ transients. Strikingly, the second application of LHRH was capable of reproducing the suppression of Ca2+ signals, indicating that the refractoriness to LHRH had not been established in neonatal rats. These results suggest that responsiveness to LHRH has a long-term refractoriness in adult rats, and that the physiological LHRH surge may be clocked in the morning. Moreover, LHRH-induced excitation and associated refractoriness appear to be incomplete in neonatal rats and may be acquired during development.

Effect of strontium on the contractile properties of postnatally developing rat heart ventricles

1985 ◽  
Vol 63 (1) ◽  
pp. 9-17 ◽  
Author(s):  
Matti Vornanen
Keyword(s):  
Rat Heart ◽  
Age Groups ◽  
Contractile Properties ◽  
Neonatal Rat ◽  
Calcium Stores ◽  
Adult Rats ◽  
Adult Rat ◽  
Twitch Potentiation ◽  
Developing Rat ◽  
T System

The effects of substitution of calcium (Ca) by an equimolar concentration of strontium (Sr) on isometric contractions of isolated ventricular muscle from postnatally developing rat heart were studied. The duration of contraction and the time-to-peak tension were increased in all age groups although much less in the adult rats than in the neonates. The contractile force was increased in the muscles of rats between 1 and 14 days of age but was depressed in the older animals. The prominent rest-twitch potentiation of neonatal rat heart in Ca− Tyrode was totally eliminated by Sr, whereas a clear rest-twitch potentiation was induced by this cation in the adult rat heart, in which tissue the potentiation is normally absent in Ca− Tyrode. The maximal twitch potentiation by rest in Ca− Tyrode and the positive inotropic effect of Sr substitution grew from birth up to day 9 and from then gradually declined towards the level of adult rat heart by the end of the 3rd postnatal week. The phase of increasing rest-twitch potentiation coincides fairly well with the known development of sarcoplasmic reticulum and the phase of decline with the appearance of the T system of the sarcolemma. It is suggested that the qualitative changes in the contractile properties of developing rat heart during the 3rd postnatal week are due to the more efficient utilization of intracellular calcium stores, owing to the development of the T system.

CARTILAGE RESPONSE TO PLASMA AND PLASMA SOMATOMEDIN ACTIVITY IN RATS RELATED TO GROWTH BEFORE AND AFTER BIRTH

1981 ◽  
Vol 90 (1) ◽  
pp. 133-142 ◽  
Author(s):  
D. J. HILL ◽  
S. J. ANDREWS ◽  
R. D. G. MILNER
Keyword(s):  
Body Weight ◽  
Costal Cartilage ◽  
Basal Medium ◽  
Tail Length ◽  
Rat Plasma ◽  
Neonatal Rat ◽  
Postnatal Life ◽  
Fetal Life ◽  
Adult Rats ◽  
Adult Rat

Cartilage response to plasma, plasma somatomedin activity, body weight and length were measured in rats from 15 days of fetal age to 37 days postnatally. The metabolic activity of costal cartilage was assessed by the incorporation of [35S]sulphate in basal medium and after stimulation by plasma. It was found that (a) A significant stimulation of isotope uptake above basal levels occurred in the presence of 15% standard adult rat plasma at every age studied. (b) The degree of stimulation, a measure of cartilage sensitivity to plasma growth factors, increased through the latter part of fetal life but fell after birth. A high degree of cartilage stimulation was seen on day 6 of postnatal life. (c) The changes in cartilage sensitivity and in the stimulated isotope uptake, resembled the changes observed in growth rate for body weight, nose–rump length and tail length. (d) Plasma somatomedin activity measured by the pig costal cartilage assay was low in the fetus and neonate but rose to adult values 9 days after birth. However, plasma from fetal or neonatal rats tested on cartilage from rats of the same age was equipotent to adult rat plasma. (e) Plasma from hypophysectomized adult rats had a low potency in stimulating isotope uptake by neonatal rat cartilage but was equipotent to normal adult rat plasma in its action on fetal cartilage. (f) The action of plasma from hypophysectomized rats on fetal cartilage was unaffected by dialysis but was destroyed by incubation with trypsin.

Comparison of extraction methods for insulin-like growth factor-binding proteins prior to measurement of insulin-like growth factor-I in undernourished neonatal and adult rat serum

1994 ◽  
Vol 140 (2) ◽  
pp. 257-263 ◽  
Author(s):  
F Rivero ◽  
L Goya ◽  
A M Pascual-Leone
Keyword(s):  
Growth Factor ◽  
Binding Proteins ◽  
Extraction Methods ◽  
Rate Of Change ◽  
Neonatal Rat ◽  
Insulin Like Growth Factor ◽  
Adult Rats ◽  
Rat Serum ◽  
Adult Rat ◽  
Igf I

Abstract Insulin-like growth factors (IGFs) are considered to be endocrine regulators during development, and different species have been used for the study of these factors during the perinatal period. The neonatal rat is a very useful model widely utilized to study endocrine alterations throughout the developmental period; few references in the literature present the neonatal rat as a model for the study of IGFs however. This study was undertaken to compare two extraction methods, acid–ethanol cryoprecipitation (AEC) and formic acid–acetone (FA), for the removal of IGF-binding proteins (IGFBPs) from neonatal and adult rat serum in fed (control) and undernourished populations prior to measurement of IGF-I by radioimmunoassay (RIA). The IGF-I values obtained by RIA following AEC or FA extraction were compared with those obtained following gel filtration (GF), which is considered to be the reference method. Western ligand blotting was used to determine IGFBPs in unextracted serum and after AEC or FA extraction of serum from rats of 10 and 20 days of age and adult rats in both populations. Although serum IGF-I levels after AEC or FA in adult control rats were comparable with those obtained following GF, a significant correlation was found only after AEC extraction both in fed and undernourished adult rats. During the neonatal period, at 10 and 20 days, serum IGF-I levels after AEC or FA extraction were very different from those obtained after GF, especially in undernourished populations, and the correlation was very poor at 10 and 20 days of age in both populations studied. The IGFBP radioligand blots showed a different rate of change in control and undernourished rats during the period studied. Changes in IGFBP-3 and the band at 30 kDa are reported in both control and undernourished animals. The different proportions of the three major IGFBPs remaining after AEC or FA extraction were also shown. We conclude that AEC extraction, originally validated for use in human serum, is also satisfactory for use in adult but not in neonatal rat serum. However, FA extraction was not a useful method for the rat serum. In neonatal rat serum, the only reliable extraction method was GF. Journal of Endocrinology (1994) 140, 257–263

Increased 11β-hydroxysteroid dehydrogenase type-1 and hexose-6-phosphate dehydrogenase in liver and adipose tissue of rat offspring exposed to alcohol in utero

2007 ◽  
Vol 292 (3) ◽  
pp. R1101-R1109 ◽  
Author(s):  
Srinivas Nammi ◽  
Korami Dembele ◽  
B. L. Grégoire Nyomba
Keyword(s):  
Prenatal Alcohol Exposure ◽  
Adult Life ◽  
Alcohol Exposure ◽  
Hydroxysteroid Dehydrogenase ◽  
Prenatally Exposed ◽  
Adult Rats ◽  
Insulin Resistant ◽  
Adult Rat ◽  
Rat Offspring

Rat offspring prenatally exposed to alcohol display features of metabolic syndrome characterized by a low birth weight, catch-up growth, dyslipidemia, and insulin-resistant diabetes with increased gluconeogenesis, during adult life. Gluconeogenesis is partly regulated by cyclic AMP- and glucocorticoid-dependent mechanisms. Glucocorticoid action at the receptor level depends on its circulating concentrations and is amplified at the prereceptor level by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), which regenerates active glucocorticoids from inactive forms. To determine whether 11β-HSD1 is dysregulated in this rat model, we examined the expression and enzyme activity of 11β-HSD1 and its regulator enzyme hexose-6-phosphate dehydrogenase (H6PD) in the liver of postnatal day 7 (neonatal) and 3-mo-old (adult) rat offspring prenatally exposed to alcohol. Measurements of 11β-HSD1 and H6PD were also performed in the omental fat of adult rat offspring. In both neonatal and adult rats, prenatal alcohol exposure resulted in increased tissue corticosterone concentrations, increased expression, and oxoreductase activity of 11β-HSD1, and a parallel increase of H6PD expression. The data suggest that due to both transcriptional and posttranscriptional dysregulations, rats exposed to alcohol early in life have increased 11β-HSD1 activity, which may explain insulin-resistant diabetes in these animals later in life.

Intestinal uptake and transport of proteins in the adult rat

1978 ◽  
Vol 203 (1151) ◽  
pp. 177-189 ◽  
Keyword(s):  
Protein Transport ◽  
The Body ◽  
Neonatal Rat ◽  
Electron Microscopic Level ◽  
Electron Microscopic ◽  
Intestinal Uptake ◽  
Adult Rats ◽  
Adult Rat ◽  
Old Rats ◽  
Bovine Immunoglobulin

The transport of immunoglobulin and ferritin across the intestinal mucosa of adult rats provides an excellent model for transcellular protein transport study. Intestinal uptake and transcellular transport have been extensively studied in the neonatal rat, but not to such an extent in the adult rat. The transport of 125 I labelled bovine immunoglobulin G and ferritin was studied in 100 days old rats using intestinally administered proteins. Antigen was estimated in the tissues by reacting extracts against specific immune antiserum prepared in rats, and visualization studies were carried out by fluorescence microscopy and direct deposition autoradiography at electron microscopic level. From these studies, it can be seen that these proteins are taken up by the intestinal cells and transported, antigenically intact, across the barriers to the body organs.

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