The effect of thyroidectomy on male rats fed two antagonist lipid diets. IV. The fatty acid content of mitochondrial lipids of heart and gastrocnemic muscles

The fatty acid (FA) contents of heart and gatrocnemic muscle mitochondrial lipids of thyroidecromized and control (sham-operated) were analyzed. Animals were fed either an n-6 polyunsaturated (PUFA)-rich diet A or an n- PUFA-rich diet B during 30 days. It was observed alteraions in the composition of FA of those cell organelles caused by the absence of the thyroid gland. Some of these alterations were dependent of the type of used diet. Thyroidecromy caused an increase of P?S ratio in heart and gastrocnemic muscle but only for animals fed diet B. Thyroidectomy caused an increase of n-6/n-3 ratio in heart of rats fed diet A and in gastrocnemic muscle of rats fed diet B and it caused a decrease of n-6/n-3 ratio of heart of rats fed diet A and in gastrocnemic muscle of rats fed diet B. The absence of thyroid gland in some way may interfer in the FA metabolism and in the rate of FA incorporation into endogeneous lipids but in a different process dependent of type of tissue and of used lipid diet

The effect of the thyroidectomy in male rats fed two antagonist lipid diets. V. The mitochondrial ATPase activity of heart and gastrocnemic muscles

The mitochondrial ATPase activity of heart and gastrocnemic muscles of thyroidectomized and control rats was determined. Some rats were fed an n-6 polyunsaturated fatty acids (PUFA)-rich diet A and others were fed an n-3PUFA-rich diet B, during 30 days. The heart mitochondrial ATPase activity of rats fed diet A was higher than of rats fed diet B in both thyroidectomized (p < 0.01) and control (p < 0.05) groups. The thyroidectomy induced an increase of heart mitochondrial ATPase activity in both dietary groups (p < 0.01). The thyroidectomy also induced an increase in gastrocnemic mitochondrial ATPase activity in diet B group, but it induced a decrease in ATPase activity in diet A group. The data suggest that the dietary lipids and the absence of thyroid gland induce changes in mitochondrial ATPase activity in heart and gastrocnemic muscles, confirming the same observations previously y described for the effect of thyroidectomy and diet in rat liver and brain (9)

Effect of the thyroidectomy on male rats fed two antagonist lipid diets: I. Physiological aspects

Male rats fed an n-6 polyunsaturated fatty acid (PUFA)-rich diet A or an n-3 PUFA-rich diet B were subjected to a surgical thyroidectomy or to a sham-operation (control animals). Thyroidectomy caused a lesser daily increase of body weight in both dietary groups. The diet A rats showed in average greater values of body weight than diet B rats, for control and thyroidectomized animals. After 30 days of experiment thyroidectomy caused no effect on the relative weight (g/100g body weight) of liver in both dietary groups. However, it increased the relative weight) of gastrocnemius (p<0.05) and brain (p<0.001) in both dietary groups, and it decreased the relative weight of heart in both dietary groups, and it decreased the relative weight of heart in diet A (NS) and in diet B (p<0.05) groups. The relative weights of heart, gastrocnemius, liver and brain of control and thyroidectomized rats of diet A groups were lower than respective organs of diet B groups. Thyroidectomy did not affect the level of plasma proteins of diet B rats was higher than diet A rats, for controls or thyroidectomized animals. Iodine uptake by thyroid gland, the plasma level of T3 of diet B control rats were significant higher thand diet A control rats, but the plasma level of T4 of diet A control rats was higher than diet B control rats (NS). These results suggested that the thyroidectomy and or lipid diets may alter the rat development as well the ingestion of antagonist lipid diets may alter thyroid gland functions

The effect of the thyroidectomy in male rats fed two antagonist lipid diets: II. The fatty acid content of lipids of plasma and mitochondria of liver and brain

Male rats subjected to surgicl thyroidectomy showed alteration in the content of fatty acids (FA) of plasma and mitochondria of liver and brain lipids in comparison to control animals (sham-operated). Those alterations depend of the kind of dietary fat intake. Control and thyroidectomized rats fed an n-6 polyunsaturated fatty acid (PUFA)-rich diet A or an n-3 PUFA-rich diet B. Thyroidectomy, independently of kind of diet, did not cause any alteration on the P/S ratio in plasma or brain mithocondria. However, it caused an increase on the P/S ratio in liver mithochondria, more evident in the dietary group B. This fact may suggest that the absence of thyroid hormones would induce a higher incorporation of PUFAs in liver lipids. Thyroidectomy caused a decrease of linoleic acid (LA) content in plasma of both dietary groups but it caused an increase of LA in diet A brain mitochondria groups. The plasma FA content, although depends on the source of fat intake, was not a mere reflection of the diet FA ingested. As the thyroidectomy also changed the content of plasma FA, it is possible to postulate that the plasma FA should be actually a reflection of the FA content of endogenous lipds

The effect of thyroidectomy in male rats fed two antagonist lipid diets: III. The liver and brain mitochondrial ATPase activity

The liver and brain mitochondrial ATPase activity of surgical thyroidectomized male rats fed two antagonist lipid diets, an n06 polyunsaturated fatty (PUFA)-rich diet A or an n-3 PUFA-rich diet B, during 30 days, was different in comparison to the respective controls (sham-operated animals). Thyroidectomy did not change the diet A liver and diet B brain ATPase activity, but it increased the diet B liver ATPase (p<0.001) and decreased the diet A brain ATPase (p<0.001). The ATPase activity was also altered in function of used diets, with the exception of thyroidectomized rats in liver. The ATPase of diet A control rats was higher than the enzyme of diet B control rats in liver (p<0.001) and brain (p<0.001). The ATPase of diet A thyroidectomized rats was higher than the diet B thyroidectomized rats ATPase (p<0.005)

Estudo das alteracoes de eixo hipotalamo-hipofise-tiroide de ratos alimentados com excesso de colesterol. / Hypothalamo-pituitary-thyroid axis function in rats fed with excess of cholesterol

Neste estudo verificou-se o efeito da administracao de colesterol pela dieta (1%) sobre a secrecao hipofisaria de TSH e Prl em um sistema in vitro de coincubacao hipotalamo-hipofise.A atividade do TRH nos extratos hipotalamicos dos ratos alimentados com colesterol foi maior do que aquela observada nos extratos controles, indicando que o aumento das concentracoes sericas e hipofisarias de TSH e Prl evidenciadas apos o periodo de alimentacao com colesterol e provavelmente devido a uma maior secrecao de TRH pelo hipotalamo

Conversao de tiroxina (T4) em 3,5,3'triiodotironina (T3) e 3,3',5-triiodotironina (reverso T3) em suspensoes de leucocitos humanos. Estudo nos estados de hiper e hipotiroidismo. / Thyroxine (T4) to 3,5,3'-triiodothyronine (T3) and 3,3',5-triiodothyronine (reserve T3) conversion in human leukocyte suspensions. Study in hyper and hypothyroidism states

O metabilismo periferico dos hormonios tiroidianos foi estudado em suspensoes de leucocitos humanos, determinando-se, por radioimunoensaio, agestao in vitro de T3 e rT3 a partir de T4 nao radioativo. Pode-se evidenciar, nas suspensoes de leucocitos provenientes de pacientes portadores de hipertiroidismo, maior geracao in vitro de T3 e rT3, enquanto que diminuicao significativa foi observada nos pacientes com hipotiroidismo. Essas alteracoes sao aparentemente devidas ao excesso e a falta de hormonios tiroidianos, respectivamente, ja que em ambos os casos elas puderam ser revertidas pelo tratamento clinico adequado

Respostas da glandula tireoide do rato macho frente ao excesso de colesterol dietetico. Influencia da casracao. / Response of the thyroid gland of male rats in face to the dietary cholesterol. Influence of castration

Ratos machos alimentados com dieta enriquecida em colesterol (1g.) apresentam aumento da captacao e do conteudo de l3lI, na glandula tireoide. Ha, ao mesmo tempo, incremento na taxa plasmatica de TSH, indicativo de hiperatividade secretoria tireo-estimulante da adenohipofise. Apresenta-se tambem aumento da taxa plasmatica de PBI131 devido a maior secrecao tireoideana, porem a taxa de T4 livre diminui e a de T3 aumenta, fenomenos decorrentes de exagerada interconversao de T4 a T3. Em ausencia total das gonadas, o colesterol dietetico falha como agente direo-estimulante, dado que a captacao de I131 pela tireoide nao se altera. A falta de gonadas aparentemente tambem interfere na interconversao T4 - T3, nao havendo mudancas na taxa plasmatica de T4 enquanto que a T3 diminui. Poder-se-ia concluir que o colesterol dietetico, estimula a funcao tireoideana atraves de um mecanismo tipo feed-back negativo gatilhado pela diminuicao de T4 livre que determina aumento do TSH. Este mecanismo nao se apresentaria em ausencia de testiculos, pelo qual pode-se deduzir que a gonada masculina e fundamental para os efeitos tireo-estimulantes provocados pelo colesterol