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L Macho

Publications and source records attributed to L Macho.

At least 109 records · Page 6Linked to original sources
PubMed1979

Comparison of the effect of TRH on plasma TSH level in young and adult rats.

Since it is known that TRH degrading system in plasma is inactive during suckling period in the rat, it was of interest to see whether this might prolong the effect of TRH on plasma TSH. Time course of plasma TSH after s. c. administration of 2 ng TRH g-1 was studied in 7, 48 and 120 day-old rats. The highest basal TSH level (448 +/- 72 microU ml-1) was found in 48 day-old males, while it was the lowest (82 +/- 22.8 microU ml-1) in 7 day-old animals. Time course was essentially the same in all three age groups. If the increase of plasma TSH was compared to the level of saline treated controls at the same time, 8.2 and 10.1 fold increase was found 10 and 30 min after TRH injection, respectively, in 7 day-old pups. However, the increase was only 2.3 and 3.4 fold in older animals at the same time intervals. The highest absolute level obtained during TRH stimulation was found in 48 day-old animals (1055 +/- 121.6 microU ml-1). These results show that the effect of TRH on plasma TSH was not prolonged in neonatal rats thus suggesting that extravascular TRH degradation may be of some importance in TSH regulation.

Aging↗
PubMed1979

Age-related differences in the effect of glucagon on metabolism in rat liver.

The authors found differences in the metabolic response of 10- and 120-day-old rats to glucagon. In 10-day-old young, the administration of glucagon was followed in 5 min by an abrupt small increase in the blood sugar level, which continued to rise and attained the maximum 2 hours after the injection of glucagon. In adult rats there was an abrupt large increase in the blood sugar level in the first minutes after administering glucagon; after that the blood sugar level fell, but remained significantly higher than in the controls. In a series of experiments on the isolated perfused liver, no differences were found in glucose and protein release from the liver into the perfusion medium, but the protein concentration in the liver of the younger rats fell. The results show that the liver of young rats, after the injection of glucagon, draws on its own protein resources for the substrates needed for gluconeogenesis.

Aging↗
PubMed1979

Age differences in the effect of glucagon on the metabolism of glucose precursors in perfused rat liver.

The effect of glucagon on the uptake and incorporation of 14C-pyruvate and 14C-alanin into glucose was studied in perfused liver of young (aged 10 days) and adult (aged 120 days) male rats. It was found that the processes studied were significantly higher (P less than 0.005) in young animals, the difference being still more remarkable after the injection of glucagon (10 microgram kg-1) to the animals (liver donors) one hour before the dissection of liver.

Aging↗
PubMed1978

Changes of adrenal catecholamines and their synthesizing enzymes during ontogenesis and aging in rats.

Male Wistar specific-pathogen-free rats aged 2, 7, 17, 30, 60, 120, 200, 360 and 600 days, all killed in experiment on the same day, were examined. The body weight significantly increased until the 200th day, the weight of adrenals until the 120th day and the adrenal protein content until the 30th day of life. The adrenaline content of the adrenals increased continuously during the 600 days studied. Adrenal noradrenaline content increased rapidly over the first 17 days, remained at a stable level until the 120th day, and rose to a higher level after 200 days. The activity of adrenal catecholamine-synthesizing enzymes also increased with age: tyrosine hydroxylase gradually increased until the 360th day, dopamine-beta-hydroxylase and phenylethanolamine-N-methyl transferase until the 200th day. Our results demonstrate that, in the rat, during development there is a gradual increase of adrenal weight, adrenaline content, tyrosine hydroxylase and phenylethanolamine-N-methyl transferase activity until maturation (120th day), whereas the adrenal noradrenaline content reaches the adult values earlier, around the 17th day. During aging, adrenal catecholamines significantly increase when compared to young-adult rats (120-day-old), probably due to the elevated activity of the adrenal catecholamine-synthesizing enzymes. The increased adrenal catecholamine levels in old animals might be connected with a higher incidence of cardiovascular diseases in aged.

Adrenal Glands↗
PubMed1978

Thyroid activity in early weaned and suckling infants and their lactating mothers.

The activity of thyroid gland was estimated in a group of lactating mothers and their suckling infants as well as in a group of early weaned infants. In both groups of infants the same level of thyroxine and triiodothyronine was found, but it was higher than that in mothers. The binding properties of specific plasma proteins and free thyroxine index were the same in both groups of infants. The level of TSH in serum of suckling infants (4.7 +/- 0.5 microunits ml-1) was significantly higher (P less than 0.01) than that in weaned infants (3.0 +/- 0.3 microunits ml-1). The level in mothers (4.0 +/- 0.3 microunits ml-1) did not differ significantly from that in both groups of infants. A positive correlation was found between the level of TSH in lactating mothers and their suckling infants (r = +0.494, P less than 0.05). The data suggest that the regulation of thyroid activity in infants may be affected by suckling.

Female↗
PubMed1978

The effect of lactation on thyroid activity of women.

The study comprised 12 lactating (L) women, 26 women who interruped the lactating during study (IL) and 6 women failing to lactate (NL). All women gave birth to normal fullterm infants after uneventfull pregnancy and vaginal delivery. Sampling was done during the 2nd day and 10th week after parturition. Lactating women showed more pronounced decrease of thyroxine, decreased thyroxine: triiodothyronine ratio and increased TSH level during the 10th week after parturition in comparison to IL group. The women on NL group showed similar changes as L women, but without increased level of TSH in comparison to IL ones. Results suggest the effect of lactation on the thyroid activity. This effect could be due to the loss of iodine and thyroid hormones to the milk.

Adolescent↗
PubMed1977

Increase of serum thyrotropin (TSH) os suckling rats after thyroliberin (TRH) injection to lactating mothers.

Injection of 50 microgram TRH to lactating rats 15 days after parturition was followed 4 h after treatment by an increase of serum TSH and a decrease of absolute and relative pituitary TSH content in suckling pups when compared to sucklings of saline-treated mothers. The weight of the pituitary and thyroid also decreased. Results indicate that TRH administered to lactating rats induces release of TSH from the pituitary of suckling pups. An increase of the variability of serum TSH and a decrease of pituitary TSH content at noon in pups of saline-treated mothers suggest the presence of diurnal variation of TSH secretion in 15-day-old rats.

Animals↗
PubMed1977

Effect of premature weaning on the fatty acid composition of rat adipose tissue.

The authors described the effect of premature weaning on the fatty acid spectrum in the retroperintoneal fat of female rats during ontogenesis. Premature weaning reduced the lower fatty acid content [decanoic acid C 10:0, lauric acid C 12:0, myristic acid C 14:0] in 30- to 90-day-old rats, but in further development no differences between the amount of these fatty acids were observed in suckled and prematurely weaned animals. These changes concurred with the fatty acid composition of the relevant diet (rat milk and a standard laboratory diet). Changes induced in the amount of other acids by premature weaning were not permanent in character, with the exception of stearic acid C 18:0 and linoleic acid C 18:3, which were raised at 720 days in the retroperitoneal fat of prematurely weaned rats. The amount of lower saturated fatty acids fell with advancing age, whereas oleic C 18:1, linolic C 18:2 and linolenic C 18:3 acid rose.

Adipose Tissue↗
PubMed1977

Effect of insulin on glucose metabolism in isolated adipocytes and in diaphragm: effect of age and neonatal nutrition.

Differences in the response of isolated adipocytes to insulin were found in relation to the age and early postnatal nutrition. In old rats (15 months) an impaired stimulation of 14C-glucose incorporation into lipids was found after insulin as compared to young animals (1 or 2 months old). In isolated fat cells from young neonatally underfed rats a higher increase of insulin induced lipogenesis was observed than in controls. The response to insulin, however, was not influenced by neonatal nutrition inold rats. Glucose oxidation in the diaphragm was also lower in older animals (4 months) than in young (1 month) rats. The stimulation of glucose oxidation by insulin was higher in neonatally underfed rats as compared to overfed ones during the suckling period. The rise of glucose oxidation after insulin decreased with age. These results showed that the response of muscular and adipose tissue decreases by age and that nutrition during the early postnatal period may affect the influence of insulin on the metabolsim of glucose in adipose and muscular tissue in young animals.

Adipose Tissue↗
PubMed1976

Influence of early weaning on the activity of several enzymes in the liver of rat.

In normally weaned rats the activity of two enzymes in rat liver, i.e. ATP citrate lyase and malic enzyme, gradually increases between the end of the third and the beginning of the fourth postnatal week. The activity of mitochondrial alpha-glycerophosphate oxidase remains unchanged during this period. Early weaning on the 18th postnatal day causes a rapid increase in activity of these enzymes. The impulse for this increase is very probably the change from high fat milk diet to high carbohydrate standard laboratory diet, the decrease of blood lipids, the activation of thyroid gland and changes of sensitivity of hepatic cells towards thyroid hormones. These results showed that early weaning modifies to the known picture of physiological weaning to a great extent.

ATP Citrate (pro-S)-Lyase↗
PubMed1976

Plasma corticosterone during postnatal ontogenesis in rats: comparison of protein-binding and fluorometric method.

Competitive protein-binding method was used for determination of plasma corticosterone levels in rat during postnatal ontogenesis until 600 days of age. The level of corticosterone was high after birth, decreased until 5th day of life and then again increased at the end of the second week. During adolescence, when the sexual differentiation begins the levels of plasma corticosterone in females become permanently higher than those of males. Moreover, the comparison of plasma corticosterone level as measured with the aid of competitive protein-binding method and fluorometric method was described in hypophysectomised, stressed and normal male rats. The correlation between both methods was satisfactory, but the results obtained with a competitive protein-binding method were, on an average, by 35% lower. The specificity, precision and recovery of competitive protein-binding assay were found to be satisfactory. This method was found to be of advantage for a determination of plasma corticosterone level in small laboratory animals because of a small volume of plasma necessary.

Aging↗
PubMed1976

Effect of gamma irradiation on biological activity of thyrotropin.

The biological activity of thyrotropin (TSH) was tested after sterilization by 0.5 and 12.5 Mrad of gamma irradiation. It was found that the biological activity (McKenzie's assay) of TSH irradiated in dry state was not affected during the first month after sterilization by doses of 0.5 and 2.5 Mrad. However, substantial decrease of TSH biological activity was observed 3--5 months after the irradiation, the lower activity being after the former dose. The irradiation of TSH by 12.5 Mrad in dry state and by 0.5 and 2.5 Mrad in solution resulted in a decrease of biological activity already during first month. The structural changes in the molecule of TSH were apparently not very extensive, since a decrease of disulfide bonds from 0.96 to 0.77 M per 1M of TSH was found immediately after the irradiation, while UV absorbancy and electrophoretic mobility on polyacrylamide gel electrophoresis were unaffected. These changes were followed by the decrease of TSH stability during storage in dry state. It is hypothesized that TSH molecule may be affected in beta subunit or in its connection with alpha.

Disulfides↗