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F Goglia

Publications and source records attributed to F Goglia.

At least 55 records · Page 3Linked to original sources
PubMed1994

In vitro binding of 3,5-di-iodo-L-thyronine to rat liver mitochondria.

In this study we have demonstrated that specific binding sites for 3,5-di-iodo-L-thyronine (3,5-T2) can be detected in rat liver mitochondria. After incubation with the homogenate, liver mitochondria bound only a small portion of [3,5-125I]T2. The addition of a 100-fold excess of unlabelled 3,5-T2 caused the displacement of on average 50-60% of the [3,5-125I]T2 bound. Specific binding of 3,5-T2 to rat liver mitochondria occurred rapidly; a maximum was achieved after 5 min. Maximal binding was obtained at 37 degrees C, while at 0 degrees C and 20 degrees C the values were only slightly lower. Binding was maximal at pH 7.0; mean (+/- S.E.M.) values for the apparent association constant and the binding capacity (calculated at pH 7.0, 0 degrees C and after 30 min of incubation) were 0.5 +/- 0.04 x 10(8) M-1 and 0.4 +/- 0.04 pmol/mg mitochondrial protein respectively. The specificity of binding, examined in competition studies, followed the order: 3,5-T2 > 3,3'-di-iodo-L-thyronine > 3',3,5-tri-iodo-L-thyronine > thyroxine. Other iodothyronines (3',5'-di-iodo-L-thyronine, 3,5-di-iodo-D-thyronine, 3,3',5'-tri-iodo-L-thyronine, 3-iodo-L-thyronine and 3,5-di-iodothyroacetic acid) showed little or no competition. This suggests that the specific 3,5-T2 binding sites could be of biological relevance with respect to the understanding of the mechanism of physiological action of thyroid hormones at the cellular level.

Adenosine Triphosphate↗
PubMed1993

Effect of cold acclimation on oxidative capacity and respiratory properties of liver and muscle mitochondria in ducklings, Cairina moschata.

1. The effect of cold acclimation on the oxidative capacity of the skeletal muscle (gastrocnemius and pectoralis) and the liver of ducklings was investigated. 2. In cold-acclimated (CA) ducklings, the oxidative capacity of the liver was higher (+40%) than in ducklings reared at thermoneutraility (TN). In these animals an increase in state 4 respiration and a decrease in the respiratory control index (RCI) was also found. 3. The oxidative capacity of both pectoralis and gastrocnemius muscles also increased in CA animals. 4. In these muscles the oxidatibe capacity of the subsarcolemmal mitochrondrial fraction of CA ducklings was higher (+96% in the gastrocnemius and +58% in the pectoralis) than the intermyofibrillar one (+51% in the gastrocnemius and +33% in the pectoralis). No variations were observed in either the RCI or the ADP/O ratios. 5. These findings indicate that the energy expenditure needed for non-shivering thermogenesis (NST) in cold-acclimated ducklings can be met by the increase in the oxidative capacity of the skeletal muscle and the liver, each by different mechanisms; the gastrocnemius muscle would seem to play a prominent role.

Acclimatization↗
PubMed1993

Effect of 3,3'-di-iodothyronine and 3,5-di-iodothyronine on rat liver mitochondria.

In the present study we report that 3,3',5-tri-iodothyronine (T3) as well as two iodothyronines (3,5-di-iodothyronine (3,5-T2) and 3,3'-di-iodothyronine (3,3'-T2)) significantly influence rat liver mitochondrial activity. Liver oxidative capacity (measured as cytochrome oxidase activity/g wet tissue) in hypothyroid compared with normal rats was significantly reduced (21%, P > 0.01) and the administration of T3 and both iodothyronines restored normal values. At the mitochondrial level, treatment with T3 stimulated respiratory activity (state 4 and state 3) and did not influence cytochrome oxidase activity. On the other hand, both the mitochondrial respiratory rate and specific cytochrome oxidase activity significantly increased in hypothyroid animals after treatment with 3,3'-T2 or 3,5-T2 (about 50 and 40% respectively). The actions of both iodothyronines were rapid and evident by 1 h after the injection. The hepatic mitochondrial protein content which decreased in hypothyroid rats (9.6 mg/g liver compared with 14.1 in normal controls, P < 0.05) was restored by T3 injection, while neither T2 was able to restore it. Our results suggest that T3 and both iodothyronines have different mechanisms of action. T3 acts on both mitochondrial mass and activity; the action on mitochondrial activity was not exerted at the cytochrome oxidase complex level. The action of the iodothyronines, on the other hand, is exerted directly on the cytochrome oxidase complex without any noticeable action on the mitochondrial mass.

Animals↗
PubMed1992

Effect of 3,3'-diiodothyronine and 3,5-diiodothyronine on rat liver oxidative capacity.

We report that 3,5,3'-triiodothyronine (T3) as well as two other iodothyronines (3,3'-diiodothyronine and 3,5-diiodothyronine (T2s)) stimulate rat liver oxidative capacity (measured as cytochrome oxidase activity (COX)). In hypothyroid rats COX activity and mitochondrial protein content are significantly lower than in normal control animals. The administration of both T3 and T2s to hypothyroid rats significantly enhances hepatic COX activity with T3 having the greatest effect (+60%); moreover, T3 restores the mitochondrial protein content whereas the T2s are ineffective. Administration of T2s results in a faster stimulation (already significant 1 h after the injection) of hepatic COX activity than T3 injection. Our results suggest that T3 acts on the protein synthesis mechanism involved in the regulation of the mitochondrial mass while T2s would act directly at the mitochondrial level.

Animals↗
PubMed1992

Morphometric-stereologic analysis of brown adipocyte differentiation in adult mice.

Brown adipocyte differentiation from interstitial stem cells was analyzed by morphometric-stereologic methods in adult mice. Confirming previous studies, four different stages of development were identified: 1) interstitial cells----2) protoadipocytes (interstitial cells with tiny lipid droplets)----3) preadipocytes----4) mature brown adipocytes. Brown adipocyte precursor cells (interstitial cells and protoadipocytes) occupied only a small fraction of total brown adipose tissue (BAT) volume (1.7 and 1.8%, respectively). Most of the BAT volume was occupied by fully differentiated multilocular cells (65% vol/vol), preadipocytes (12%), and blood capillaries (10%). The differentiation of protoadipocytes into preadipocytes was characterized by a doubling in the cellular volume (from 800 to 1,500 microns 3) that was associated with a fivefold increase in the number of mitochondria (221 to 1,464), an eightfold augmentation in mitochondrial size (from 0.042 to 0.37 microns 3), a fourfold increase in the surface density of the inner mitochondrial membrane (from 8 to 35 microns 2/microns 3), resulting in a 14-fold enlargement in the relative volume of the mitochondrial compartment (from 2 to 29%). This remarkable mitochondrial proliferation was accompanied by an increase in the number and volume of cytosolic lipid droplets. In contrast, the differentiation of preadipocytes into brown adipocytes was mainly characterized by a doubling in the size of the lipid compartment; the mean volume of single droplets increased 35 times but their number decreased 6-7 times. The mitochondrial modifications were minor; there was only a slight increase in the surface density of the inner membrane. In conclusion, the major step of brown adipocyte differentiation consists in the transformation of protoadipocytes into preadipocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue, Brown↗
PubMed1990

Liver and brown fat mitochondrial response to cold in the garden dormouse (Eliomys quercinus).

The involvement of two organs, i.e. the liver and the brown adipose tissue (BAT) in response to cold in a hibernating species such as the garden dormouse has been studied. 2. In animals living in the cold, mitochondrial respiratory rates significantly increased (with respect to those living at 28 degrees C) in both organs with a larger increase in the BAT (+152% in the BAT and 67% in the liver). 3. The increase in BAT activity was obtained by a concomitant increase in: (a) the BAT mass (+30%), (b) the total mitochondrial mass (+20%), and (c) the mitochondrial respiratory rate (+64%). In the liver the increase was due only to an augmentation in mitochondrial mass and activity. 4. These results indicate that: (a) the BAT exerts a pre-eminent role in the physiological response to cold of garden dormouse, (b) a certain non-shivering thermogenesis (NST) is present in the liver of such species. In addition we suggest that a local thermoregulatory response would take place in a metabolically important organ such as the liver.

Acclimatization↗
PubMed1990

Elevated hepatic mitochondrial oxidative capacities in cold exposed rats.

1. Hepatic mitochondrial oxidative capacities were studied in rats exposed to cold for periods ranging from 5 to 15 days. The mitochondria obtained in this study were well coupled as shown by RCR and ADP/O ratios. 2. The liver mitochondria of cold exposed rats showed significantly increased respiratory rates (ng atoms of oxygen consumed min-1 mg prot-1), starting from day 10 of cold exposure, using lipid and non-lipid substrates. 3. For non-lipid substrates, the elevated respiratory rates found in the mitochondria could indicate an increased capacity to oxidize these substrates. For the lipid substrate, on the other hand, an enhanced oxidation through Krebs-cycle of a part of acetyl-CoA otherwise utilized to form ketone bodies, could also occur. 4. Taken together the results suggest that, during cold exposure, liver mitochondria could participate in cold adaptation mechanisms, by improving ATP production.

Acclimatization↗
PubMed1989

The effect of thyroid state on respiratory activities of three rat liver mitochondrial fractions.

In this paper we report that three different rat liver mitochondrial fractions, differing in density, exhibit differential effects when the animals are made hypo- or hyperthyroid. The investigations have been performed by correlating the protein content, the succinic dehydrogenase behaviour and the respiratory features of the three fractions in different thyroid states with morphometric-stereologic analysis the electron micrographic level. The results indicate that the thyroid hormone influences both the mass and the functionality of the heavy (H) and light (L) fraction. In hypothyroid rats the H fraction increases (+43%) while the L fraction decreases (-32%) and their respiratory activity is drastically reduced. Adenosine triphosphate (ATP) synthesis in the H fraction is also inhibited. Triiodothyronine (T3) administration to the above animals restores the values observed in control rats. At morphometric level we note in hypothyroid rats an increase in the number of mitochondria together with a concomitant increase in the average volume of a single mitochondrion. We are inclined to explain the above results through an action exerted by T3 on a hypothetical mitochondrial cycle starting with the formation of light organelles from heavy ones.

Animals↗
PubMed1989

Morphological and functional modifications of rat liver peroxisomal subpopulations during cold exposure.

A report is made (during cold exposure) of: a) the morphometric-stereologic analysis both on the whole rat liver peroxisomal population, and on 2 peroxisomal subpopulations having a diameter greater than 0.5 microns, and less than 0.5 microns, called Pe (Peroxisomes) and sPe (small Peroxisomes), respectively; b) the uricase and palmitoyl-coenzyme A oxidase activity assay on 2 classes of rat liver peroxisomes, sedimenting at 10,000 g and 27,000 g and containing Pe and sPe, respectively. The peroxisomal volume and number densities increase during cold exposure, reaching a maximum (+67% and +130%, respectively, P less than 0.05) at 10 days. These modifications are accompanied by an appreciable reduction of the average peroxisome volume (from 0.27 +/- 0.05 microns 3 to 0.19 +/- 0.02 microns 3) due to a major percentage increase of sPe during cold exposure. At a qualitative level, the formation of "clusters" and a stricter association between mitochondria and peroxisomes is also observed. Cold exposure increases the oxidative capacity of the whole peroxisomal compartment; in the Pe fraction the palmitoyl-CoA oxidase and uricase specific activity ratio is constant (about 0.1), during cold exposure, but in the sPe fraction this ratio increases significantly (from 0.05 to 0.09). The results indicate that the peroxisomal population is influenced during cold exposure, with the formation of a new peroxisomal population which is on average smaller and more specialized for the beta-oxidative activity. The possible involvement of peroxisomes in thermoregulatory thermogenesis during cold exposure is also discussed.

Animals↗
PubMed1989

Effects of 3,5,3'-triiodothyronine (T3) on rat liver peroxisomal compartment during cold exposure.

In this study, by enzymatic assays and morphometric-stereologic analyses, we show that the remodelling of the rat liver peroxisomal compartment, occurring during cold exposure, is largely influenced by the thyroid state of the animal. The research was performed both on the whole rat liver peroxisomal population and on 2 peroxisomal subpopulations: one having a diameter greater than 0.5 microns, sedimenting at 10,000 g and called Pe (Peroxisomes); and the other having a diameter less than 0.5 microns, sedimenting at 27,000 g and called sPe (small Peroxisomes). The increase in the peroxisome number and in the peroxisome volume densities, elicited by cold exposure, is greatly reduced in hypothyroid cold-exposed animals (-63% and -40% respectively, P less than 0.01), while triiodothyronine (T3) administration to these rats restores the values observed in normal cold-exposed animals. The "clusters" and the strict association between mitochondria and peroxisomes, more frequently found in cold-exposed rats, are rarely observed in hypothyroid cold-exposed animals. At peroxisomal enzymic level, the thyroid hormone inhibits, during cold exposure, the uricase activity (-29% in Pe and -40% in sPe), and stimulates the palmitoyl-coenzyme A oxidase activity (+44% in Pe and +88% in sPe). The results also demonstrate that T3 exerts all these effects by acting principally on sPe.

Animals↗
PubMed1988

Light mitochondria and cellular thermogenesis.

We show that remarkable differences exist among 3 mitochondrial subpopulations with regard to oxidation-phosphorylation coupling. In the heavy fraction (sedimenting at 3,000 g) ATP synthesis is optimized while in the medium and light fractions (sedimenting at 10,000 and 27,000 g, respectively) heat production tends to be optimized as the mitochondrial size decreases. As the oxygen consumption of the L-fraction drastically increases (+150%) after fifteen days of cold exposure, such differences have remarkable implications for the mechanism of cellular thermogenesis and its regulation.

Adenosine Triphosphate↗
PubMed1988

Mitochondrial DNA, RNA and protein synthesis in normal, hypothyroid and mildly hyperthyroid rat liver during cold exposure.

We have examined in isolated liver mitochondria the effect of cold exposure on DNA, RNA and protein synthesis in normal, hypothyroid and mildly hyperthyroid rats. In normal rats DNA polymerase activity increased from the first day of cold exposure remaining high up to the fifteenth day. RNA polymerase and protein synthesis were stimulated from the fifth day of cold exposure, maintaining a high level up to the fifteenth day. These activities were related to serum triiodothyronine (T3) levels. Indeed propylthiouracil (PTU) administration to cold-exposed rats drastically depressed the above activities, whereas T3 administration to PTU-treated cold-exposed rats restored them to about the values prevalent in normal cold-exposed rats. The translation products analyzed by gel electrophoresis showed that different effects may be exerted by T3 depending on whether its circulating levels are physiologically or pharmacologically modified. These findings suggest that T3 may be involved in the regulation of the acclimation process by acting, presumably with a permissive role, on those activities which determine a modification of the mitochondrial morphometric features and an increase in mitochondria number and turnover.

Animals↗
PubMed1986

Tri-iodothyronine enhances the formation of light mitochondria during cold exposure.

The effect of cold exposure and of PTU and PTU + T3 administration on the protein content and succinic dehydrogenase activity of three mitochondrial populations obtained from rat liver was examined. Our results indicated the following: Succinic dehydrogenase activity increases mainly in the light mitochondrial fraction of cold-exposed rats. PTU administration of cold-exposed animals does not affect the increment in enzyme activity of the heavy fraction but blocks the increment of the light fraction. PTU + T3 administration restores succinic dehydrogenase activity to the values prevalent in normal cold-exposed rats. These findings suggest that thyroid hormone may stimulate the formation of light mitochondria during cold exposure.

Acclimatization↗
PubMed1985

Triiodothyronine receptor sites in serum-free cultured hepatocytes from adult rat liver.

Nuclear T3 specific binding sites were characterized by Scatchard analyses of L-125I-T3 binding to nuclei extracted from freshly isolated and 1, 2 and 6 day-cultured hepatocytes. The results demonstrate a marked decrease in T3 binding capacity of nuclei extracted from 1 day-cultured cells followed by an almost complete recovery within 6 days. The affinity constant value of nuclear receptor sites is significantly decreased in 1 day-cultured cells with a subsequent partial recovery. The affinity and capacity pattern of nuclear T3 binding sites appears to be in line with the delayed responses of hepatocyte primary cultures to T3.

Animals↗
PubMed1985

Alteration in hepatic mitochondrial compartment of cold-acclimated rats. Association with enhanced triiodothyronine serum levels. A morphometric/stereologic study by electron microscopy.

In cold-exposed rats, the circulating levels of free and total T3 rapidly increase and reach higher values after 2 h, 70% and 80%, respectively. These values remain constant during cold exposure and return to normal values after few hours of re-exposure to room temperature. A remarkable modification of the mitochondrial compartment in rat hepatic cells is associated with these hormonal variations. The morphometric stereologic analysis shows that after 10 days of cold exposure the number of mitochondria per nucleus is nearly doubled (from 1,912 to 3,414), the total volume of the mitochondrial compartment per nucleus increases by about 40% (from 21% to 29%), and the mitochondrial membrane surfaces per nucleus increase too (from 7,233 square microns to 11,597 square microns for the outer membranes; from 31,572 square microns to 42,603 square microns for the inner membranes + cristae). The mean mitochondrial volume decreases by about 25%. This probably indicates, the formation of new organelles by division of pre-existing mitochondria. On re-exposure to room temperature, there is a return to normal values. The present data suggest the existence of a physiological long-term mechanism for the regulation of cellular thermogenesis during cold exposure (increase in number of mitochondria per cell), associated with enhanced levels of T3.

Acclimatization↗
PubMed1983

Thyroid state and mitochondrial population during cold exposure.

Young rats exposed to the cold (4 degrees C) for 15-25 days exhibit remarkable modifications in their thyroid state and in the mitochondrial population of target organs such as liver. The serum total and free T3 levels more or less doubled (from 77 +/- 7 to 130 +/- 7 ng/100 ml and from 350 +/- 25 to 530 +/- 25 pg/100 ml, respectively) after 2 h of exposure while the serum total T4 levels underwent a limited and transitory increase; mitochondrial alpha-glycerophosphate dehydrogenase activity increased. On re-exposure to room temperature the thyroid state returned to normal. Cold exposure diminished the cellular volumes of hepatic cells, while the successive warm re-exposure increased the number of liver cells. The number of mitochondria per nucleus increased after 5 days of cold exposure and doubled after 10 days (from 1,200 +/- 120 to 2,400 +/- 130), while the mean protein content per organelles exhibited an exactly contrary trend. These results suggest that during cold acclimatization, the thyroid, the thyroid plays a role in inducing an augmentation of mitochondrial membrane surfaces per cell by stimulation of the mitochondrial protein synthesizing mechanism. At present, it is not possible to establish whether these effects are due to transcriptional modifications of the nuclear genome only or, more likely, to a dual action at nuclear and mitochondrial level.

Animals↗
PubMed1981

In vitro binding of triiodothyronine to rat liver mitochondria.

Saturable high affinity T3 binding sites were detected in a mitochondrial fraction enriched in internal membranes and partly solubilized by Triton X-100. Specific T3 binding to the solubilized sites, only detected at low T3 concentrations, was optimal at pH 8.0 and not dependent upon the presence of divalent cations or reducing agents; it was destroyed by heat and proteolytic enzymes. The solubilized T3 binding sites were distributed, after Sephadex G-200 gel filtration, between two peaks of similar affinity for T3 (Ka congruent to 5 x 10(10)l/mol) and similar binding characteristics. T3 was bound with a high stereospecificity, while some analogues of biological importance (L-T4; 3,5,3'-triiodothyroacetic acid; 3,3';-diiodo-L-thyronine) competed with L-T3 in the same range of low concentrations. This suggests that the high affinity mitochondrial T3 binding sites could be of biological relevance in the mitochondrial metabolism.

Animals↗