Effects of castration on the content and labelling of lipids in male rat liver

Castration reshapes the liver by altering fatty acid composition and metabolism in male mice

Castration promotes subcutaneous fat deposition that may be associated with metabolic adaptations in the liver. However, fatty acid composition, abundance, and metabolic characteristics of the liver after castration are not fully understood. Our results showed that surgical castration significantly reduced water and food intake, reduced liver weight, and induced liver inflammation in mice. Transcriptome analyses revealed that castration enhanced fatty acid metabolism, particularly that of arachidonic and linoleic acids metabolism. Gas chromatography-mass spectrometry analysis revealed that castration altered the composition and relative abundance of fatty acids in the liver. The relative abundances of arachidonic and linoleic acids were significantly decreased in 4-week-old castrated mice. Analysis of fatty acid synthesis- and metabolism-related genes revealed that castration enhanced the transcription of fatty acid synthesis- and oxidation-related genes. Analyzing the level of key enzymes in the β-oxidation and tricarboxylic acid cycle pathways of fatty acids in mitochondria, we found that castration enhanced the β-oxidation of fatty acids in mitochondria, and also enhanced the protein level of the rate-limiting enzyme in the tricarboxylic acid cycle pathway, isocitrate dehydrogenase 2. These results comprehensively clarify metabolic changes in liver fatty acids after castration in mice of different ages and provide a reference for understanding castration-induced fat deposition from the perspective of liver fatty acid metabolism in male mice.

Does long-term androgen deficiency lead to metabolic syndrome in middle-aged rats?

Evidence from clinical observational studies and animal experiments suggests that hypogonadism is associated with the metabolic syndrome. In most of the experiments, androgen deficiency is induced by gonadectomy in the adulthood and relatively short-term effects of hypogonadism on metabolic parameters are usually observed. The purpose of this study was to evaluate the metabolic effects of long-term androgen deficiency starting before puberty in middle-aged male rats. The components of the metabolic syndrome were examined in male, female and gonadectomized male rats at the age of 18months. Sex differences were observed in plasma testosterone, cholesterol, high-density lipoproteins and also in body weight and in glycemia dynamics during oral glucose tolerance test. Gonadectomy and long-term hypogonadism did not affect most of the analyzed metabolic parameters such as blood pressure, glycemia, plasma insulin and uric acid. The only exception was the significantly higher liver enzymes in plasma and triacylglycerol in liver found in gonadectomized males. Except low-density lipoprotein, neither treatment of middle-aged males and females with letrozole, nor supplementation of estradiol as the metabolite of testosterone in gonadectomized male rats changed any of the observed metabolic parameters. Our results suggest that long-term hypogonadism started before puberty does not induce metabolic syndrome in middle-aged male rats, but may affect the liver. Sex differences in metabolic parameters in middle-aged rats are not mediated by testosterone. Whether hypogonadism predispose to metabolic syndrome in combination with other risk factors needs further clarification.

Effects of chronic exposure to cadmium on prostate lipids and morphology

Cadmium is an environmental toxic metal implicated in human prostate carcinogenesis. The mechanism of its toxicity is not fully understood. Previously, we showed that cadmium exposure induces oxidative stress, especially lipid peroxidation. This study evaluates the effect of chronic exposure to 0.886 mM of cadmium (Cd) per liter in the drinking water on prostate lipid content and metabolism in Wistar rats. We determined the lipid profile and measured the expression of lipogenic enzymes: FAS, GPAT, LPL, DGAT-1, DGAT-2, ACO, CPT-1 and CT, and of certain factors involved in lipid regulation and fatty acid transporters: FAT/CD36, E-FABP, SREBP-2, PPAR-gamma and PPAR-alpha by RT-PCR. Ultrastructure was analyzed by electron microscopy and, as prostate is an androgen controlled gland, AR expression was measured by RT-PCR and Western blot. Cd altered the prostatic lipid profile. Triglycerides (TG) and esterified cholesterol (EC) decreased, free cholesterol (FC) and phospholipids (PL) increased and total cholesterol (TC) did not change. FAS, MDH and IDH activities did not vary but G6PDH decreased significantly in Cd group. Regarding TG synthesis, DGAT-1 decreased while GPAT increased and FAS, LPL and DGAT-2 remained unchanged. Regarding beta oxidation, CPT-1 increased while ACO expression decreased in Cd group. In the PL pathway, CT expression was increased. All these results would justify the decrease of TG in Cd group when compared to control. In the cholesterol metabolic pathway, HMGCoAR and SREBP-2 increased. PPAR-alpha increased but PPAR-gamma did not change. Regarding fatty acid transporters, FAT/CD36 decreased, while E-FABP increased. AR mRNA and protein expression decreased. Ultrastructural analysis showed a decrease in lipid droplets and signs of cellular damage in the Cd group. Cadmium exposure induces important changes in prostatic lipid profile and metabolism, confirmed by the morphology analyses, which also showed signs of cellular damage. These results could be important to further understanding the complex mechanism of cadmium toxicity in prostate and in the development of better treatments for people and animals exposed to the heavy metal.

Lung lipid composition in zinc-deficient rats

There have been a limited number of studies investigating surfactant lipid changes in lung with trace elements. The present investigation was designed to examine the effect of moderate zinc deficiency on the lipid metabolism in rat lung. We also evaluated whether zinc deficiency, which is a wide-spread problem, could play a role in adult respiratory distress syndrome (ARDS). For that purpose, adult male Wistar rats were fed two diets differing in zinc concentration. The rats were divided into two groups. One group was fed a zinc-deficient diet containing 3 mg Zn/kg, and the other group received a zinc-adequate control diet with 30 mg Zn/kg according to AIN 93-M. After 2 mon of treatment, we observed that in the zinc-deficient group (i) total lipids, phospholipids, and cholesterol increased whereas TG decreased in whole lung; (ii) phospholipid (PC) concentration increased in lamellar bodies and alveolar macrophages and decreased in extracellular surfactant but did not change in microsomes; (iii) protein concentration decreased in whole lung, extracellular surfactant, lamellar bodies, and macrophages; (iv) the incorporation of [Me-14C]choline into PC (phospholipids) of lung slices increased; and (v) the activity of CTP/phosphocholine cytidylyltransferase bound to the microsomes increased in the lung. These results suggest that the lipid concentration in the lung (especially the phospholipids) is modified directly or indirectly by a zinc-deficient diet. In a zinc-deficient diet, the lung changes the pattern of PC for an adaptive or recovery stage. Therefore, zinc deficiency implications are important for the design of therapies and public health interventions involving targeted zinc supplementation for high-risk groups or groups with certain diseases, such as ARDS.

Androgen regulation of lung lipids in the male rat

The aim of this study was to determine whether or not testosterone regulates the lipid concentration in rat lung tissue. Rats were either sham-operated controls, castrated, or castrated and injected with testosterone. Twenty-one days after castration, we observed in relation to the control: (i) Total lipids, phospholipids, and total cholesterol increased, while triglycerides decreased in whole lung. (ii) Phospholipid concentration increased in microsomes, lamellar bodies, and alveolar macrophages, but it decreased in extracellular surfactant. (iii) On a percentage basis, the concentration of phosphatidylcholine increased in microsomes, lamellar bodies, and alveolar macrophages, and it decreased in extracellular surfactant. (iv) Protein concentration decreased in extracellular surfactant and increased in microsomes, lamellar bodies, and alveolar macrophages. (v) The incorporation of [14C]glycerol into phospholipids of lung slices increased. (vi) The activity of CTP:phosphocholine cytidylytransferase bound to the microsomal fraction increased without any change in the activity of the soluble form of the enzyme in the lung. The results obtained when testosterone was administered to castrated rats were similar to those obtained in the control in all cases. These results suggest that the lipid concentration in the lung is regulated at least partly directly or indirectly by androgens.