Effect of pyritinol, a cerebral protector, on learning and memory deficits induced by prenatal undernutrition and environmental impoverishment in young rats

The study was conducted on 64 CF strain albino rats, which were equally distributed into 8 evenly matched groups following a 2 x 2 x 2 factorial design, by varying three independent factors at two levels: nutrition--normal and undernutrition; environment--enrichment and impoverishment, and drug treatment--vehicle and pyritinol (100 mg/kg, ip). Prenatal undernutrition was induced by restricting the mother's food intake. The environmental enrichment/impoverishment and the vehicle/pyritinol treatments were given during the postweaning period of the pups. The rats were subjected to original and subsequent reversal brightness discrimination learning tests in a single unit T-maze at 8-9 weeks of age. Thereafter, the animals were tested for the passive avoidance learning. The results indicate that undernutrition caused significant original discrimination learning deficits whereas environmental deprivation attenuated both the original and reversal learning performance. Environmental impoverishment attenuated the retention of passive avoidance behaviour but undernutrition had no effect on this paradigm. Pyritinol treatment improved the learning and retention performance of normally reared rats and also attenuated the original and reversal learning deficits induced by parental undernutrition and postweaning environmental impoverishment. The results indicate that pyritinol may be useful in learning and memory deficits induced by malnutrition and environmental deprivation.     

Effect of piracetam, a nootropic agent, on discrimination learning deficits induced by parental undernutrition and environmental impoverishment in young rats

The study was conducted on 64 Charles Foster albino rats which were equally distributed into 8 even-matched groups, following a 2 x 2 x 2 factorial design by varying three independent factors at two levels: nutrition--normal and undernutrition, environmental--enrichment and impoverishment, and drug treatment--vehicle and piracetam (100 mg/kg, ip). Prenatal nutrition was induced by restricting the mother's food intake. The environmental enrichment/impoverishment and the vehicle/drug treatments were given during the postweaning period of the rat pups. The animals were subjected to original and subsequent reversal brightness discrimination learning tests in a single unit T-maze at 8-9 weeks of age. The results indicate that undernutrition and environmental impoverishment significantly attenuated the original discrimination as well as the reversal discrimination learning. Piracetam treatment improved the learning performance of normally reared rats and also attenuated the original and reversal learning deficits induced by prenatal undernutrition and postnatal impoverishment. The results indicate that piracetam may be useful in memory deficits induced by malnutrition.     

Effect of prenatal diazepam, phenobarbital, haloperidol and fluoxetine exposure on foot shock induced aggression in rats.

Different groups of pregnant rats were treated with diazepam (10 mg/kg), phenobarbital (10 mg/kg), haloperidol (0.1 mg/kg), fluoxetine (10 mg/kg) and vehicle (normal saline) intraperitoneally once a day during gestation days 13 to 21. After birth these pups were culled to 8 pups/dam and foster-nursed by lactating mothers for 3 weeks and were reared in colony cages thereafter. Sex and weight matched pairs of rat offsprings were subjected to foot shock induced aggression test at 8 weeks of age. Two parameters of aggressive behaviour were recorded namely, the latency to fight and total number of fighting bouts. The results indicate that prenatal exposure to diazepam, phenobarbital, haloperidol and fluoxetine caused significantly enhanced aggression in terms of number of fighting bouts.     

Molecular phylogeny of mangroves V. Analysis of genome relationships in mangrove species using RAPD and RFLP markers

 DNA from pooled leaf samples of 11 true major mangrove, three true minor mangrove, two mangrove associate, two mangrove parasite, three terrestrial and one cultivated species were isolated for the present study. In total, 198 random amplified polymorphic DNAs (RAPDs) and 180 restriction fragment length polymorphism (RFLP) loci were scored by using ten primers and 14 enzyme-probe combinations respectively. The polymorphism observed for these markers revealed a high degree of genetic diversity in mangroves at both inter-specific or inter-generic levels. A dendrogram, constructed after pooling both RAPD and RFLP data, using a similarity index was analysed for genome relationships among these species. The dendrogram showed clustering of all the major mangroves, except for Nypa fruticans (Arecaceae), into one group. All species under the tribe Rhizophorae formed a sub-cluster, to which Xylocarpus granatum was found to be the most closesly related species. The clustering pattern implied that Excoecaria agallocha and Acanthus ilicifolius should be considered as true minor mangroves. The present study also provided molecular data favouring the separation of Avicennia spp. from the Verbenaceae to create a monotypic family the Avicenniaceae. The separation of Viscum orientale into the Viscaceae was also favoured. Received: 5 March 1998 / Accepted: 1 April 1998     

Rate of transport and development of preimplantation embryo in the superovulated buffalo (Bubalus bubalis)

This study was designed to ascertain the rate of transport and development of preimplantation embryo in the superovulated buffalo in order to determine the optimum time for their nonsurgical collection. Eighteen Murrah-type buffalo were superovulated with 600 mg NIH-FSH-P1. Luteolysis was induced by administration of PGF2 alpha at 72 (PG + 72) and 84 h (PG + 84) after initiating gonadotrophin treatment and fixed-time AI was done beginning at 36 h post PG + 72 administration and at 12-h intervals thereafter, upto 72 h. Six control buffalo received treatment similar to experimental group except that in place of FSH they received normal saline. For embryo collection, experimental animals were humanely killed at 6-h intervals corresponding to 156 (n = 2), 162 (n = 2), 168 (n = 2), 174 (n = 3), 180 (n = 3), 186 (n = 3) and 192 h(n = 3) after PG + 72 treatment, whereas the control animals were humanely killed at 156 (n = 2), 174 (n = 2) and 192 h (n = 2). Superovulated buffalo had higher number of ovulations than untreated controls (8.78 +/- 5.00 vs 0.67 +/- 0.51) and total ova/embryos recovered was 4.11 +/- 2.46 and 0.67 +/- 0.51, respectively. The high estradiol-17 beta (E2) levels with its prolonged rise may, by leading to reverse peristalsis in the oviduct with a consequent loss of some embryos in the peritoneal cavity, be one of the reasons for our inability to recover nearly 84/158 ova/embryos in the superovulated buffalo. In superovulated animals, nearly all the ova/embryos reached the uterus between 168 and 174 h post PG + 72 treatment or about 134 h (circa 5.5 d) after the onset of superovulatory estrus, suggesting that the ideal time for non-surgical embryo collection in the buffalo is between Days 7 to 8 after PG + 72 treatment or Days 5.5 to 6.0 of the superovulated cycle (estrus = Day 0). Embryo development of superovulated buffalo showed considerable variation as various stages of embryos (8 cell to expanded blastocyst) were recovered from the same donor buffalo, and the rate of development appeared to be 24 to 36 h faster than in cattle.     

Efficient in vitro repair of 7-hydro-8-oxodeoxyguanosine by human cell extracts: involvement of multiple pathways.

To investigate the repair of oxidative damage in DNA, we have established an in vitro assay utilizing human lymphoblastoid whole cell extracts and plasmid DNA damaged by exposure to methylene blue and visible light. This treatment has been shown to produce predominantly 7-hydro-8-oxodeoxyguanosine (8-oxodG) in double-stranded DNA at low levels of modification. DNA containing 1. 6 lesions per plasmid is substrate for efficient repair synthesis by cell extracts. The incorporation of dGMP is 2.7 +/- 0.5 times greater than the incorporation of dCMP, indicating an average repair patch of 3-4 nucleotides. Damage-specific nicking occurs within 15 min, while resynthesis is slower. The incorporation of dGMP increases linearly, while the incorporation of dCMP exhibits a distinct lag. Extracts from xeroderma pigmentosum (XP) complementation groups A and B exhibit 25 and 40%, respectively, of the incorporation of dCMP compared with normal extracts, but extracts from an XP-D cell line exhibit twice the activity. These data suggest that the efficient repair of 8-oxodG lesions observed in human cell extracts involves more than one pathway of base excision repair.     

Scaffold-based spheroid models of glioblastoma multiforme and its use in drug screening

Among several types of brain cancers, glioblastoma multiforme (GBM) is a terminal and aggressive disease with a median survival of 15 months despite the most intensive surgery and chemotherapy. Preclinical models that accurately reproduce the tumor microenvironment are vital for developing new therapeutic alternatives. Understanding the complicated interactions between cells and their surroundings is essential to comprehend the tumor's microenvironment, however the monolayer cell culture approach falls short. Numerous approaches are used to develop GBM cells into tumor spheroids, while scaffold-based spheroids provides the opportunity to investigate the synergies between cells as well as cells and the matrix. This review summarizes the development of various scaffold-based GBM spheroid models and the prospective for their use as drug testing systems.     

Phosphorylation and dephosphorylation of tyrosine 141 regulate stability and degradation of INrf2: a novel mechanism in Nrf2 activation

INrf2-Nrf2 proteins are sensors of chemical/radiation stress. Nrf2, in response to stresses, is released from INrf2. Nrf2 is translocated into the nucleus where it binds to the antioxidant response element and coordinately activates the expression of a battery of genes that protect cells against oxidative and electrophilic stress. An autoregulatory loop between INrf2 and Nrf2 regulates their cellular abundance. Nrf2 activates INrf2 gene expression, and INrf2 serves as an adapter for degradation of Nrf2. In this report, we demonstrate that mutation of tyrosine 141 in bric-a-bric, tramtrack, broad complex domain to alanine rendered INrf2 unstable and nonfunctional. INrf2Y141A mutant degraded rapidly as compared with wild type INrf2, although it could dimerize and bind Nrf2. De novo synthesized INrf2 protein was phosphorylated at tyrosine 141. Tyrosine 141-phosphorylated INrf2 was highly stable. Treatment with hydrogen peroxide, which is an oxidizing agent, led to dephosphorylation of INrf2Y141, resulting in rapid degradation of INrf2. This resulted in stabilization of Nrf2 and activation of ARE-mediated gene expression. These results demonstrate that stress-induced dephosphorylation of tyrosine 141 is a novel mechanism in Nrf2 activation and cellular protection.