M.L. Thakur

Vitamin-E metabolism and its application

Vitamin E, the most active form is alpha-tocopherol, widely distributed in nature with different biological activities. It is a major lipid-soluble antioxidant responsible for protecting membranes against lipid peroxidation which could slow the aging process in humans or animals. Several roles of vitamin E have been reported such as antioxidant, intermediary in arachidonic acid and prostaglandin metabolism, nucleic acid, protein and lipid metabolism, mitochondrial function, sex hormones production, in maintaining the integrity of membranes, in protection against hemolytic anemia and impaired erythropoiesis, reducing the risks of heart disease, cancer, neurological diseases, cataract, retinopathy of premature infants and arthritis. Vitamin E deficiency results in neurological syndrome in people with chronic malabsorption. It is useful in the neurological diseases such as Parkinsons, Huntingtons, epilepsy and tardiv dyskinesia. Several clinical applications of vitamin E are known in diseases such as abetalipoproteinemia, cystic fibrosis, cholestic liver disease, hemolytic anemias, respiratory distress, epilepsy, burns, aging, cancer, ischemic heart disease and cataract. The future study of vitamin E in humans or animal models should provide more definitive evidence of its absorption, transport, utilization and retention in various body organs and tissues as well as in protection and prevention of major neurological diseases.

Protein and RNA biosynthesis in various cellular fractions of the brain of undernourished rats

Abstract Body and brain weight; DNA, RNA, and protein content; total free nucleotides; amino acids and their specific activities; as well as the in vitro incorporation of 14C-phenylalanine into protein and of 2H-orotate into RNA of homogenates and various cellular brain fractions were measured in well-fed (WF) and undernourished rats during gestation (EI) and during growth, gestation, and lactation (EII). Body weight was significantly decreased in both EI and EII while brain weight and DNA content per organ were lower in EII than in WF and EI rats. The brain weight:DNA ratio was increased significantly in EII animals compared with the WF group. RNA content did not show any significant alterations in homogenates, nuclear, microsomal and pH-5 enzyme fractions but was elevated in mitochondrial and soluble fractions of the brain of EI rats compared with the WF group. Brain RNA content in EII animals was decreased in homogenates and all cellular fractions with the exception of the nuclear fraction in which it did not change significantly. The RNA:DNA ratio tended to increase (non-significantly) in the EI and EII groups as compared with the WF controls. Protein content was decreased in homogenates and all cellular fractions of EII rats while it was reduced only in the mitochondrial and pH-5 enzyme fractions of the EI group. The RNA:protein ratio fell in the microsomal fraction and rose in the soluble and pH-5 enzyme fractions of EI and EII animals. The protein:DNA ratio increased significantly in homogenates and the nuclear fraction of the EII Group: 14C-phenylalanine/mg protein incorporation was augmented in homogenates, mitochondrial, and soluble fractions, was diminished in the microsomal fraction, and did not change in the nuclear fraction of the brain of EI and EII rats. 3H-Orotate/mg RNA incorporation was decreased in the nuclear and microsomal fractions and was increased in the soluble and pH-5 enzyme fractions of the brain of EI and EII groups. Incorporation was also elevated in brain homogenates of EII rats and was reduced in the EI group. It was increased in the mitochondrial fraction of EI animals but did not show any change in the EII group. From these results, it can be concluded that dietary stress during gestation alone (EI) and during growth, gestation, and lactation (EII) modulates the metabolism of nucleic acids and proteins in the whole brain and in various cellular brain fractions.

Maternal food restriction, brain polysomes and poly-U stimulated protein synthesis in the newborn and 21-day-old rat progeny

Abstract Effect of maternal dietary restriction during the period of gestation (EI) and during the period of growth, gestation and lactation (EII) on (i) the polysomal profiles (ii) distribution of 14 C-phenylalanine and 3 H-orotate into membrane bound and free polysomes and ribosomes and (iii) ribosomal response to the addition of poly-U in the incorporation of 14 C-phenylalanine was investigated in the brain of the neonatal (N) and 21-day-old (T) progeny. Polysomal profile showed variable degrees of reductions in the membrane bound ribosomes, free polysomes and monoribosomes in the brain of N and T progeny of EI and EII groups compared with WF group. Distribution of radioactive phenylalanine and orotate also showed variable responses in the membrane bound ribosomes free polysomes and the monoribosomes of the brain of N and T progeny of EI and EII groups. EII N progeny generally had a lower distribution and EII group T progeny had a higher distribution than EI group in each component of the polysomal profile. Ribosomes from the brain of N and T progeny of EI and EII groups responded less actively to the addition of poly-U than WF group. Synthesis of protein/synthesis of polyphenylalanine ratio (which roughly represents polysomes/monosomes ratio) demonstrated variable responses in the brain of N and T progeny of EI and EII groups compared with WF group. In T progeny when WF polysomes were incubated with EI or EII group pH-5 enzymes, the incorporation increased significantly and was higher in EII group than EI group. Incubation of EI polysomes with EII pH-5 enzyme demonstrated a significant increase in the incorporation. These results clearly demonstrate that maternal food restriction during various physiological periods had a profound effect on brain polysomes and consequently the protein synthesizing machinery in the N and T progeny.

m-RNA translatability in the liver, brain and kidney of rats: Effect of protein calorie malnutrition in early life

Abstract The m-RNA level and its translational capacity were determined in the liver, brain and kidney of rats which had been exposed to under nutrition early in life. To achieve this objective, lactating females were divided into 2 groups 1 week after they gave birth to offspring. These control and experimental groups were made to suckle 8–11 and 13–16 pups, respectively, for a period of 2 weeks. The young of both groups were then killed and their livers, brains and kidneys were isolated. Polyadenylated RNA (poly A + RNA) was fractionated by affinity chromatography on an oligo-dT-cellulose column. Poly A + RNA content as well as the percentage of poly A + RNA in relation to total RNA were both lower in the malnourished pups in comparison to the controls. Analysis of the in vitro translation product primed by poly A + RNA of the liver, brain and kidney revealed a decrease of 35 S-methionine-incorporation in the liver and brain of the dietary-insulted offspring, the reduction being greater in the liver than in the brain. No significant variation was noted in the kidney of the control and PCM groups. Sodium dodecyl sulfatepolyacrylamide gel electrophoresis, autoradiography and densitometric autoradiographic tracings confirmed these findings and demonstrated that proteins were synthesized at a lower rate in the livers and brains of the malnourished rats than in the controls. These data indicate that malnutrition early in life modulates the metabolism of m-RNA and, consequently, protein synthesis in the liver, brain and kidney of rats.

Maternal dietary-insult and the biosynthesis of protein and RNA in various cellular fractions of the brain of neonatal and 21-day-old rat progeny

Abstract The effect of maternal dietary insult during the period of gestation (EI) and during the period of growth, gestation and lactation (EII) on the body, and cellular growth (DNA, RNA and protein content), protein and RNA synthesis in the brain and various cellular fractions of the brain of the neonatal (N) and 21-day old (T) progeny was investigated. It was noted that body and organ weight failed to increase normally in the N and T progeny of EI and EII groups as compared to a well-fed (WF) group. DNA content did not show any change in the N progeny but was lower in the T progeny of EI and EII groups. RNA content and protein content showed lowering to variable degrees in various cellular fractions of N and T progeny of EI and EII groups as compared to a WF group. RNA to DNA, and protein to DNA ratio were lower in most of the cellular fractions whereas organ weight to DNA ratios was lower in the N progeny and was higher in the T progeny of EI and EII groups. The content of total nucleotides and amino acids and their specific activities showed variable responses in the N and T progeny of EI and EII groups. The synthesis of protein was higher in most of cellular factions of N progeny of EI group and T progeny of EI group. The synthesis of RNA generally was higher in most of the cellular fractions in the N progeny of EI group and EII group and in the T progeny of EII group and showed variable responses in the T progeny of EI group compared to progeny of WF group. These result indicate the profound effect of maternal dietary insult during the period of gestation and periods of gestation and lactation on the molecular and cellular development of brain of neonatal and 21-days-old progeny and also demonstrate that how these effects on the molecular and cellular development of brain will be modulated by the changes in the various cellular fractions of the brain.

Biochemical changes in progressive muscular dystrophy, XVI. Effect of glutamic acid, aspartic acid and glycine on the amino acid content of skeletal muscle of dystrophic mice.

The effect of exogenous administration of glutamic acid (GL), aspartic acid (A) and glycine (G) on individual amino acids in the free amino acid pool was studied in skeletal muscles of 60- to 70-day-old normal (N) and dystrophic (D) mice. Both N and D mice received either 0.25 ml of saline (S) or 250 mg/kg weight of GL, A or G in 0.25 ml S subcutaneously for 13 days. GL, A, G or S did not cause any significant changes in the body and skeletal muscle weights of either group. Most of the individual amino acids were increased in skeletal muscles of GL-treated mice and were decreased in A- or G-treated animals compared to S administration in the N group. The picture was more dramatic in the D group: GL-induced amino acid elevations were more pronounced than the values of N- or S-treated D controls. A and G elicited amino acid increases in D mice compared to their S-treated counterparts. Most of the individual amino acids in skeletal of the D group were decreased relative to N mice after S, GL or A administration. This was evident when the D/N ratio was calculated for S, GL and A. The situation was very different after G administration since of the individual amino acids were augmented in the skeletal muscle of D mice compared to N animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of maternal dietary deficiency on the metabolism of high-molecular weight, soluble and transfer RNA in the liver of the 21-day-old offspring of rats

Abstract The 21-day-old male progeny of dietary-restricted rats were administered 14 C-orotic acid intraperitoneally to study the metabolism of high-molecular weight soluble (sRNA) and transfer RNA (tRNA) in their livers, which were removed at various time intervals ranging from 6 to 120 minutes after the injection. DNA and total RNA were extracted from each liver sample, and nucleic acids were fractionated with 2M NaCl into insoluble (high-molecular weight) and soluble (DNA and tRNA) fractions. All the preparations were analyzed by sucrose density gradient sedimentation, and the distribution of radioactivity was determined. Dietary-restricted progeny experienced significant increases of RNA (p

Brain polysomes and poly-U simulated protein synthesis in food restricted rats

Abstract Effect of food restriction on (i) polysomal profiles (ii) distribution of 14 C-phenylalanine and 3 H-orotate into membrane bound ribosomes, free polysomes and monoribosomes, (iii) poly-U stimulated incorporation and (iv) the effect of pH-5 enzyme on the incorporation of phenylalanine by the ribosomes was investigated in the brain of rats from well (WF) and dietary restricted groups during the period of gestation alone (EI) and during the period of growth, gestation and lactation (EII). Polysomal profile showed a considerable lowering in the membrane bound ribosomes of EI and EII groups and free polysomes of EI group of rat brain compared with WF group. However, the membrane bound and free polysomes were higher in EII group compared with EI group. Monoribosomes decreased condiderably in the EII group compared with WF and EI group. Distribution of 14 C-phenylalanine/mg protein was higher in the membrane bound ribosomes and monoribosomes in the brains of EI and EII groups and also in the free polysomes in EII group compared with WF group. Distribution of radioactive orotate/mg RNA was higher in all the three components of polysomal profile of EI and EII group brain compared with WF group but it was higher only in the monoribosomes of the EII group compared with EI group. Brain ribosomes from EI and EII groups responded more actively to the addition of poly-U than WF group. Synthesis of protein/synthesis of polyphenylalanine ratio (which roughly represents polysomes/monosomes ratio) showed lower polysomal content in the EII group brain compared with WF group. WF polysomes when incubated with EI or EII group pH-5 enzyme showed considerable increases in the incorporation compared with WF pH-5 enzymes. EI group polysomes when incubated with EII group pH-5 enzyme showed remarkable increase in the incorporation compared with WF and EI pH-5 enzyme. EII polysomes when incubated with any of the three pH-5 enzyme did not show any change. These results clearly demonstrate that brain polysomes are very sensitive to dietary restriction no matter at whatever physiological conditions they are exposed to this restriction.

Maternal dietary deficiency in rats and the in vivo synthesis of cytoplasmic, nucleolar and chromosomal RNA in the liver of their 21-day-old progeny

Abstract The metabolism of cytoplasmic, nucleolar and chromosomal RNA was studied at various time intervals ranging from 6 to 120 minutes in the liver of the 21-day-old progeny of well-fed and dietary restricted rats. The dietary-restricted groups progeny demonstrated significant increases in the kinetics of labelling of cytoplasmic RNA (p