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At least 235 records · Page 13Linked to original sources
PubMed1994

Hypothalamic-pituitary-thyroid axis in chronic alcoholism. II. Deiodinase activities and thyroid hormone concentrations in brain and peripheral tissues of rats chronically exposed to ethanol.

Thyroxine (T4), triiodothyronine (T3) concentrations, and the activities of the three deiodinase isoenzymes were measured in different brain regions and peripheral tissues of rats. According to an animal model of alcohol addiction, "behaviorally" dependent rats having lost control over their intake of ethanol were compared with alcohol-naive controls and ethanol-experienced, but "controlled" consumers. The two kinds of alcohol-experienced rats were investigated either 24 hr or 3 months after ethanol withdrawal. The results of these four groups were compared with those of an ethanol-naive control group. During withdrawal, the activities of type II 5'-deiodinase (which catalyzes deiodination of T4 and T3 in the CNS) in both the "behaviorally dependent" rats and the "controlled drinkers" were significantly lower than in the alcohol-naive controls in the frontal cortex, parieto-occipital cortex, hippocampus, and striatum, but not in the cerebellum or pituitary. Probably as a result, the tissue concentrations of T4 were higher in areas of the CNS in the groups exposed to alcohol. However, the T3 concentrations were normal. No relevant differences were seen between the activities of type III 5-deiodinase (which catalyzes the further deiodination of T3) observed in these groups. After 3 months of abstinence, the type II 5'-deiodinase activities had almost returned to normal in both "controlled drinkers" and "behaviorally dependent" animals, whereas type III 5-deiodinase activity was inhibited, possibly to maintain physiological concentrations of T3 during abstinence. Indeed, the tissue levels of T3 were normal in the areas of the CNS, and the T4 levels were still elevated. However, the liver concentrations of T3 and T4 were significantly lower in the "behaviourally dependent" animals than in the "controlled" drinkers after 3 months of abstinence, whereas no differences were found between the T4 and T3 concentrations in the areas of the CNS investigated in the two groups exposed to ethanol. These results suggest that chronic administration of ethanol affects intracellular thyroid hormone metabolism in both rat CNS and liver in the highly complex manner. No direct evidence of ethanol-induced enhancement of tissue uptake or concentrations was obtained. However, taking into account the numerous similarities between the clinical picture of hyperthyroidism and the symptomatology of alcoholism, it may be hypothesized that ethanol may directly influence any step in the as yet unknown biochemical cascade of thyroid hormone function.

Alcoholism↗
PubMed2000

Expression of mammalian RF-amide peptides neuropeptide FF (NPFF), prolactin-releasing peptide (PrRP) and the PrRP receptor in the peripheral tissues of the rat.

The mRNA expression of neuropeptide FF (NPFF), prolactin-releasing peptide (PrRP) and the UHR-1/GPR10 receptor were examined using in situ hybridization in rat peripheral tissues. In the hypophysis, modest expression of PrRP and receptor mRNA were seen in the anterior lobe. The trigeminal ganglion was devoid of expression signals. PrRP and UHR-1/GPR10 receptor mRNA:s were found in the adrenal medulla and PrRP mRNA was found in the pancreas. NPFF mRNA was detected in the spleen. In the testis and epididymis, PrRP and UHR-1/GPR10 receptor mRNA:s were detected. The results suggest a limited expression of mammalian RF-amide peptides in the peripheral organs.

Adrenal Glands↗
PubMed1988

Peripheral tissue freezing in cryosurgery.

The recently formulated bioheat equation of Weinbaum and Jiji which accounts for the vascular ultrastructure and blood perfusion was applied to the freezing of peripheral tissue. Using quasi-steady approximation the temperature distribution in the two-phase tissue and the motion of the frozen front were determined. Results are in good agreement with Pennes' bioheat equation.

Body Temperature Regulation↗
PubMed1989

Exercise-mediated peripheral tissue and whole-body amino acid metabolism during intravenous feeding in normal man.

1. The effect of a daily submaximal exercise regimen on whole-body and peripheral tissue amino acid metabolism during weight-stable intravenous feeding (IVF) was evaluated in 11 normal volunteers. Five of the subjects performed 1 h of daily bicycle exercise at 75 W during IVF, while the remaining six subjects received IVF without daily exercise. Body nitrogen balance, leg and forearm plasma amino acid flux and whole-body kinetics were measured before and on day 10 of IVF using a [1-13C]leucine and [15N]glycine tracer. 2. At the end of the IVF period, exercised subjects demonstrated leg uptake of total amino acids (237 +/- 103 nmol min-1 100 ml-1 of tissue, mean +/- SEM) which was significantly (P less than 0.05) different than in non-exercised subjects (-1101 +/- 253 nmol min-1 100 ml-1 of tissue). 3. In the non-exercised forearm, a significant (P less than 0.05) decrease in total amino acid flux was observed in exercised subjects (-162 +/- 88 nmol min-1 100 ml-1 of tissue) compared with non-exercised subjects (-460 +/- 105 nmol min-1 100 ml-1 of tissue) on day 10 of IVF. 4. Efflux of 3-methylhistidine significantly (P less than 0.05) decreased from the leg in those subjects who performed daily exercise (-0.29 +/- 0.12 nmol min-1 100 ml-1 of tissue) compared with those subjects receiving IVF without daily exercise (-1.46 +/- 0.35 nmol min-1 100 ml-1 of tissue).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Evidence for a bioactive clonidine-displacing substance in peripheral tissues and serum.

Clonidine-displacing substance (CDS) from brain is biologically active in the kidney and stomach and on platelets. To determine whether CDS is contained in these and other peripheral tissues, homogenates of fresh brain, eight other organs and serum from rat were ultrafiltered (less than 10,000 mol. wt only), dried and extracted with methanol. Evaluation by radioimmunoassay (RIA) using antibodies to p-aminoclonidine showed that adrenal gland and gastric fundus (GF) contained significantly greater amounts of CDS-like radioimmunoactivity than brain; intermediate-to-low activity was present in heart, small intestine, serum, kidney and liver; lung and skeletal muscle values were near-background. RIA-positive extracts elicited well-correlated contractile activity in a GF smooth muscle bioassay; contractions persisted in the presence of antagonists of various transmitters and modulators, but were abolished by low concentrations of the calcium channel blocker verapamil. Serum levels of CDS were profoundly reduced following removal of the adrenal glands. We conclude that a CDS-like substance is present not only in brain as previously reported, but also in peripheral organs and in the circulation.

Adrenal Glands↗
PubMed1986

Demonstration of the vasopressin associated glycopeptide in the brain and peripheral tissues of the Brattleboro rat.

An antibody that recognizes the C-terminal portion of the vasopressin precursor was used to visualize this peptide (CPP) in the brain and peripheral tissues of the Brattleboro rat. CPP-immunoreactivity was detected in adrenal medullary cells and in Leydig and Sertoli cells of the testis. In addition, CPP positive cells were found in the supraoptic and paraventricular hypothalamic nuclei of colchicine treated and adrenalectomized rats. These results suggest that Brattleboro rats may make a small amount of normal vasopressin precursor.

Adrenal Medulla↗
PubMed1990

Glucose disappearance rates into peripheral tissues of adult rabbits (Silvilagus floridans), Wistar rats (Rattus rattus) and sand rats (Psammomys obesus) in relation to body weight and blood glucose concentration.

1. Glucose disappearance rates into peripheral tissues (RD) were measured in vivo in adult eviscerated, nephrectomized and adrenalectomized rabbits, Wistar rats and nondiabetic sand rats with physiological insulin concentrations in the blood. 2. The RD of Wistar rats was high (7.50 mg/kg/min) in comparison with that of rabbits (2.67 mg/kg/min). In the particular case of sand rats the RD was only 44% of that in Wistar rats having about the same body weight. 3. A 2.4-fold elevation of blood glucose above the basal level produces different increases of the RD: in rabbits 1.06-fold, in Wistar rats 1.5-fold and in sand rats 2.0-fold.

Animals↗
PubMed1988

Regulation of vasopressin and oxytocin synthesis in anterior pituitary and peripheral tissues.

Recent studies have demonstrated the presence of immunoreactive oxytocin (OT) and vasopressin (VP), OT and VP receptors and physiological functions for these two hormones in a variety of peripheral tissues, including anterior pituitary gland. The objectives of this study were to determine if (i) OT and VP genes are expressed in rat testis and anterior pituitary gland and (ii) if osmotic stimulation known to modify the regulation of OT and VP genes in hypothalamus, would modify the expression of these genes in rat testis and anterior pituitary gland. Using oligonucleotide probes (courtesy of Drs. M. Brownstein and W. Scott Young, NIMH) corresponding to the VP gene or OT gene and specific fractions of human OT and VP genes (courtesy of Dr. J. Battey, NCI) subcloned in the pGEM-3 riboprobe system, and Northern blot and slot blot techniques, OT and VP mRNAs were found in rat testis and anterior pituitary gland. When adult male rats (SD) were either deprived of drinking water or offered 2% salt solution as a sole source of drinking fluid for 72 hrs, both OT and VP mRNA levels were increased in hypothalamus, anterior pituitary gland and testis. Our data suggest that testis and anterior pituitary gland could also be sites of synthesis of OT and VP and that the same stimulus may regulate these genes in various tissues.

Animals↗
PubMed1989

Clonidine-displacing substance is present in peripheral tissues of the rat.

Clonidine-displacing substance (CDS) is biologically active in the brain, as well as the gastric fundus, platelets and vas deferens. We sought to determine whether CDS is contained within peripheral tissues in the rat. Using competitive radioimmunoassay with a clonidine-specific antiserum and 3H-p-aminoclonidine rat adrenal gland and gastric fundus were shown to contain significantly greater amounts of CDS-like radioimmunoactivity than the brain; intermediate-to-low activity was present in the heart, small intestine, serum, kidney and liver. Lung and skeletal muscle exhibited near-background levels. CDS may not be unique to the brain, but also may be synthesized and stored in peripheral organs.

Animals↗
PubMed1999

Widespread expression of GABA(A) receptor subunits in peripheral tissues.

The receptor subtypes involved in the physiological and pharmacological actions of gamma-amino butyric acid (GABA) in peripheral and endocrine tissues are not clear. Information about the molecular characteristics of GABA(A) receptors in peripheral endocrine tissues is only available for the pancreas and the adrenal medulla. Using reverse transcription (RT) polymerase chain reaction (PCR), the widespread expression of GABA(A) receptors subunits in rat peripheral tissues, including adrenal, ovary, testis, placenta, uterus, and small intestine is shown. It is shown that GABA(A) receptor subunits are expressed in multiple endocrine tissues in a tissue specific manner. These results give an insight into the likely pharmacological properties of these GABA(A) receptors in these tissues. The gonadal endocrine tissues such as the placenta, ovary and the testis express greater range of GABA(A) receptor subunits relative to the adrenal gland. The tissues with greater smooth muscle content, the small intestine and the uterus also express a smaller range of subunits subtypes.

Adrenal Glands↗
PubMed1991

Adenosinergic inhibition in hippocampus is mediated by adenosine A1 receptors very similar to those of peripheral tissues.

The amplitude of the orthodromically evoked population spike (PS) of CA1 neurons was used to investigate quantitatively adenosine receptor antagonism in guinea pig hippocampal slices. Increasing concentrations of the highly selective adenosine A1 receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX, 3-100 nM) produced parallel, rightward shifts of the dose-response curve for the N6-cyclopentyladenosine (CPA)-induced decrease in PS amplitude. Schild plot analyses of the respective antagonism data obtained in both the presence and virtual absence of endogenous adenosine yielded apparent dissociation constants (KD) of DPCPX at the hippocampal A1 receptor of 3.3 and 3.6 nM, respectively. This indicates that the inhibitory tonus generated by endogenously produced adenosine is due to tonic activation of A1 receptors. The KD values agree well with the binding affinity of DPCPX to A1 receptors determined in brain tissue sections. Since, in our preparation, Schild plot analyses of DPCPX antagonism revealed KD values close to those reported for other tissues, it is concluded that the central A1 receptor mediating adenosinergic inhibition is pharmacologically not distinct from A1 receptors identified in peripheral tissues.

Adenosine↗
PubMedDate not supplied

[Regional activity of enkephalin- and angiotensin II-forming peptidases in the rat brain and other peripheral tissues with different craving for ethanol].

Activities of enkephalin- and angiotensin II-forming enzymes (carboxypeptidase H and angiotensin-converting enzyme, ACE) were changed in different brain regions and peripheral tissues of rats with various alcohol motivation. The carboxypeptidase H activity was elevated in midbrain, striatum, hypophysis and adrenal glands, while the ACE activity was increased in hypophysis and striatum. The ACE activity was decreased two-fold in thalamo-hypothalamic region of ethanol-preferring rats.

Adrenal Glands↗
PubMed1992

Biologic markers in blood reflecting thyroid hormone effect at peripheral tissue level in patients receiving levothyroxine replacement for hypothyroidism.

Plasma fibronectin, serum procollagen-III-peptide and sex-hormone binding globulin as not specific markers of thyroid hormone effect at peripheral tissue level were determined and their values were related with serum levels of TSH, free-thyroxine and triiodothyronine during levothyroxine sodium replacement therapy for hypothyroidism. Low levels of biologic markers characteristic of hypothyroidism were normalized in consequence of hormone replacement and a negative correlation between their serum levels and TSH concentration was demonstrated in most subjects. However, in some patients a discrepancy in the response to levothyroxine between the pituitary and other target organs could be revealed. Additional evidence was disclosed that the pituitary thyrotroph sensitizes a minor decrease in serum thyroxine level, which would not be recognized by other target organs. Furthermore, it was revealed that during L-T4 replacement therapy in a large fraction of patients with subnormal serum TSH concentration blood levels of the measured markers often exceeded the upper limit of the normal range indicating the possibility of "tissue"-thyrotoxicosis beside the pituitary in other target organs, too. According to the present study which takes into consideration markers reflecting end-organ responsiveness to thyroid hormones it is recommended to adjust the dose of levothyroxine to maintain serum TSH in the normal range. For patients with subnormal TSH concentration a close follow-up is obligatory and in case od concomitantly raised free-thyroxine level the reduction of the levothyroxine dosage is proposed.

Adult↗
PubMed2001

A receptor-type guanylyl cyclase expression is regulated under circadian clock in peripheral tissues of the silk moth. Light-induced shifting of the expression rhythm and correlation with eclosion.

The mechanisms by which the circadian clock controls behavior through regulating gene expression in peripheral tissues are largely unknown. Here we demonstrate that the expression of a receptor-type guanylyl cyclase (BmGC-I) from the silk moth Bombyx mori is regulated in the flight muscles in a circadian fashion. BmGC-I mRNA was expressed from the end of the light period through the middle of the dark period. BmGC-I protein expression and cGMP levels were high around the initiation of eclosion events at the beginning of the photoperiod. The rhythm of the BmGC-I and cGMP levels free-ran in constant light and synchronized to the environmental photoperiodic cycle. The circadian regulation of BmGC-I expression was also observed in the legs but not in other tissues examined. BmGC-I therefore represents a circadian output gene that regulates eclosion behavior.

Animals↗
PubMed1994

Localization of cannabinoid receptors and nonsaturable high-density cannabinoid binding sites in peripheral tissues of the rat: implications for receptor-mediated immune modulation by cannabinoids.

[3H]CP-55,940, a high-affinity cannabinoid receptor ligand, was used for in vitro binding and autoradiography in peripheral tissues in the rat. Specific cannabinoid receptor binding was found to be restricted to components of the immune system, i.e., spleen, lymph nodes and Peyer's patches. Displacement studies showed that this binding is identical (similar Kd and structure-activity profile) to that in brain. Cannabinoid receptors in the immune system are confined to B lymphocyte-enriched areas, i.e., the marginal zone of the spleen, cortex of the lymph nodes and nodular corona of Peyer's patches. Specific binding is absent in T lymphocyte-enriched areas, such as the thymus and periarteriolar lymphatic sheaths of the spleen. Certain macrophage-enriched areas, i.e., liver and lung, lack specific binding. Thus, the single peripheral cell type that may contain cannabinoid receptors is the B lymphocyte. Numerous sites have dense binding that could not be displaced by excess unlabeled drug. These nonspecific sites were found in the liver, adrenal glands and sebaceous glands, which are high in fat content, and in the heart, pancreas, components of the male and female reproductive systems and the epithelium of the esophagus. Thus, the highly lipophilic nature of cannabinoids does not appear to be the sole determinant of nonspecific binding. The data suggest that cannabinoids may exert specific receptor-mediated actions on the immune system of rats. Perhaps, also at high concentrations, cannabinoids exert membrane effects at sites where they are sequestered nonspecifically.

Adjuvants, Immunologic↗
PubMed1996

Cholesterol-loading of peripheral tissues alters the interconversion of high density lipoprotein subfractions in rabbits.

High density lipoprotein (HDL) has been implicated in the process of reverse cholesterol transport,by which surplus cholesterol is removed from peripheral tissues and transported to the liver for excretion. It has been suggested that some subfractions of HDL may have a particular role in this process, though the underlying mechanism remains unclear. The present study was aimed at investigating the role of specific subfractions of HDL in reverse cholesterol transport. The interconversion of HDL subfractions in normal and cholesterol-loaded rabbits was studied in vivo. Rabbit HDL was separated by heparin-Sepharose affinity chromatography into six subfractions (HDL(I)-HDL(VI)), which were progressively enriched with apolipoprotein E (apo E), and varied in diameter and composition. Total HDL and its subfractions were individually labelled with 14C sucrose and injected in the rabbits. When rabbits which were not acutely loaded with [3H]cholesterol were injected with 14C-HDL(I), 70% of the label remained in this fraction while less than 5% was recovered in HDL(VI), containing the largest particles and those most enriched in apo E. No label was detectable in the liver of these animals. In rabbits which had received a prior loading of cholesterol, an average of only 18.3% of the 14C label was present in HDL(I) while approx. 40% of the label was recovered in HDL(VI). On average, 5.1% of the total 14C injected in these rabbits was recovered in the liver. It is concluded that two alternative routes for reverse cholesterol transport may be operative. While a continuous cholesterol-clearance route may be provided by particles of HDL of intermediate size, another route may be operative for clearance of excess cholesterol loaded into peripheral endothelial cells.

Animals↗
PubMed1983

Distribution of free and conjugated dopamine in monkey brain, peripheral tissues and cerebrospinal fluid determined by high-performance liquid chromatography.

The occurrence of free and conjugated dopamine was determined by high-performance liquid chromatography with electrochemical detection in brain areas, peripheral tissues, and CSF from rhesus monkeys. Free norepinephrine, epinephrine, and 3,4-dihydroxyphenylacetic acid were also determined in some tissues. Conjugated dopamine was found to be widely, but not homogeneously, distributed in this species. In the brain, conjugated dopamine was found to account for greater than 10% of the total dopamine present in the frontal cortex (74%), cingulate gyrus (31%), cerebellum (16%), and occipital cortex (11%). Conjugated dopamine accounted for 21% of the total dopamine in the liver, and ranged from 10 to 20% of the total in testicle, kidney and heart. In CSF from both the lateral ventricle and lumbar thecal sac, free dopamine was not reliably detected, but conjugated dopamine was found in all samples tested.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1975

Effects of neonatal 6-hydroxydopa treatment on monamine content of rat brain and peripheral tissues.

Treatment of rats from birth, with 6-hydroxydopa (6-OHDOPA) produced marked alterations in norepinephrine (NE) levels in the brain and spinal cord, but relatively slight changes in NE content of peripheral tissues, when rats were sacrificed at 5 weeks of age. In the neocortex, hippocampus and spinal cord 6-OHDOPA (60 mug/g i.p., 1 to 3 injections at 48 hr intervals from birth) resulted in a 20% to 85% reduction in NE. In the pons-medulla, midbrain and cerebellum, however, NE levels were elevated by 35% to 100%. Only slight alterations in NE were found in the hypothalamus, heart and spleen. Striatal levels of dopamine were unaltered by 6-OHDOPA at 5 weeks. Likewise, serotonin content of neocortex, cerebellum, pons-medulla, midbrain and hypothalamus was unchanged at 5 weeks, although slight elevations were seen in the neocortex and cerebellum at 2 weeks. The above effects indicate that neonatal 6-OHDOPA produces a relatively selective long term alteration of central stores of NE in the rat.

Animals↗