Effect of dihydroergotoxine, a cerebral vasodilator, on cognitive deficits induced by prenatal undernutrition and environmental impoverishment in young rats

The study was conducted on 64 Charles Foster 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 dihydroergotoxine (3 mg/kg, i.p.). Prenatal undernutrition was induced by restricting the mother's food intake. The environmental enrichment/impoverishment and the vehicle/dihydroergotoxine 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 passive avoidance learning. The results indicate that undernutrition caused significant original and reversal discrimination learning, deficits whereas environmental deprivation attenuated only the original discrimination learning performance. Dihydroergotoxine treatment facilitated the learning performance of rats in both the original and reversal learning tests. Nutritional, environmental and dihydroergotoxine treatments had no effect on the retention of the passive avoidance learning, both at 24 hr and 1 week intervals. Dihydroergotoxine treatment attenuated the learning deficits induced by prenatal undernutrition. The results indicate that dihydroergotoxine is not likely to be useful in cognitive deficits, induced by malnutrition, though it facilitated learning acquisition, since it had no effect on retention.     

Effect of chronic non-lethal doses of non-metals and metals on hepatic metallothionein in Channa punctatus (Bloch).

Compared to non-metal toxicants (ammonia, 1.56 ppm; and phenol, 10 ppm), the metals (CdCl2, 30 ppm; HgCl2, 16.7 ppb; and ZnCl2, 6 ppm) significantly induced hepatic metallothionein (MT) concentrations in C. punctatus, exposed independently to non-lethal doses of these toxicants for 28 days. It is suggested that hepatic MT serves as a metal-sequestering protein and is involved in the detoxication of metals only and ensures protection from toxic chemicals in ambience.     

Molecular phylogenetic analysis of actin genic regions fromAchlya bisexualis (Oomycota) andCostaria costata (Chromophyta)

Summary Actin genic regions were isolated and characterized from the heterokont-flagellated protists,Achlya bisexualis (Oomycota) andCostaria costata (Chromophyta). Restriction enzyme and cloning experiments suggested that the genes are present in a single copy and sequence determinations revealed the existence of two introns in theC. costata actin genic region. Phylogenetic analyses of actin genic regions using distance matrix and maximum parsimony methods confirmed the close evolutionary relationship ofA. bisexualis andC. costata suggested by ribosomal DNA (rDNA) sequence comparisons and reproductive cell ultrastructure. The higher fungi, green plants, and animals were seen as monophyletic groups; however, a precise order of branching for these assemblages could not be determined. Phylogenetic frameworks inferred from comparisons of rRNAs were used to assess rates of evolution in actin genic regions of diverse eukaryotes. Actin genic regions had nonuniform rates of nucleotide substitution in different lineages. Comparison of rates of actin and rDNA sequence divergence indicated that actin genic regions evolve 2.0 and 5.3 times faster in higher fungi and flowering plants, respectively, than their rDNA sequences. Conversely, animal actins evolve at approximately one-fifth the rate of their rDNA sequences.     

Receptor-operated calcium-channels in isolated rabbit jejunum.

Calcium channels were studied in isolated spontaneously rhythmic rabbit jejunum using the muscarinic agonist carbachol as stimulant. Carbachol failed to produce the characteristic phasic and tonic components of smooth muscle contractions. A variety of chemically distinct calcium antagonists, viz. bepridil, diltiazem, isradipine (PN 200-110), nifedipine, and verapamil, non-competitively inhibited the contractions. Diltiazem was most potent (-logIC50 = 8.30) and bepridil least potent (-logIC50 = 6.19) in inhibiting the contractions. The findings conclude with the presence of pharmacologically distinct receptor-operated calcium-channels, besides the potential-dependent calcium-channels, in the rabbit jejunum.     

An enzyme immunoassay of phaseolinone and its application in estimation of the amount of toxin in Macrophomina phaseolina-infected seeds.

A microtiter plate-based enzyme immunoassay has been developed for phaseolinone, a phytotoxin isolated from the culture filtrate of the plant-pathogenic fungus Macrophomina phaseolina (Tassi) Goid. The smallest amount of phaseolinone detectable by the method is 5 pg per well. The method is validated by comparison with high-performance liquid chromatography and used to confirm and estimate phaseolinone production in seeds infected with the fungus. The degree of seed inhibition correlated well with the amount of toxin produced in infected seeds, 50% inhibition being observed at a toxin concentration of 0.60 micrograms/g of wet tissue.     

Action of some retinol derivatives and their provitamins on microsome-catalyzed formation of benzo[a]pyrene-DNA adduct

Several vitamin A compounds have been tested for their ability to suppress formation of DNA adduct by the carcinogen benzo[a]pyrene (B[a]P) in an in vitro reaction catalyzed by rat liver microsomes. Retinol, retinal, 3-dehydroretinol and 3-hydroxyretinol were found to be effective inhibitors of adduct formation. Certain carotenoids that are precursors of these retinoids also displayed considerable inhibitory capacity. Carotenoids and the 3-substituted retinoids appeared to modulate the DNA adduct formation exclusively through their action on microsomal enzymes, since an effective inhibition in each case was observed on the formation of B[a]P-7,8-diol, a proximate carcinogenic metabolite of B[a]P. Unsubstituted retinoids, on the other hand, had marginal effect on enzymes but were found effective in accelerating inactivation of B[a]P-7,8-diol-9,10-epoxide, the ultimate carcinogenic metabolite that binds to DNA.     

Effect of selective monoamine oxidase A and B inhibitors on footshock induced aggression in paired rats

Effects of a selective monoamine oxidase (MAO)--A inhibitor, clorgyline, a selective MAO-B inhibitor, deprenyl, and a non-selective MAO inhibitor, nialamide, were investigated on footshock-induced aggression (FIA) in paired rats. The doses and pretreatment times of the inhibitors used were based on an earlier reported in vivo dose-response and time-course study. In addition, apomorphine, a dopaminergic receptor agonist, and beta-phenylethylamine, a preferred substrate for MAO-B, were also used to garner corroborative evidence. The results of the study indicate that selective MAO-A inhibitors are likely to attenuate FIA by augmenting central serotonergic activity, while selective MAO-B inhibitors accentuate the behaviour by facilitating dopaminergic activity. A permissive role for noradrenaline could not be delineated by the available data.     

Effect of retinoic acid on adenosine diphosphate and collagen-induced alterations in enzymes of GSH-linked antioxidant defence system of human blood platelets in vitro

Collagen stimulation of blood platelets resulted in significant increases in malondialdehyde (MDA) formation and activity of glucose-6-phosphate dehydrogenase (G6PDH) and a decrease in catalase and glutathione peroxidase (GPx). Retinoic acid (RA) pretreatment did not show any appreciable changes except for a decrease in G6PDH activity as compared with collagen alone. RA pretreatment of human blood platelets resulted in an increase in the activities of catalase and GPx, two important radical scavenging enzymes, with significant decrease in MDA formation when compared with ADP alone. It is suggested that RA has a significant effect on the antioxidant defence system in ADP stimulated platelets but not in the collagen stimulated platelets.     

Differential effect of retinoic acid on ADP and collagen induced platelet aggregation

Retinoic acid (RA) was found to inhibit ADP induced but not collagen induced aggregation of human platelets and the differential action is related to intraplatelet Ca2+ reflux. RA was active at concentrations as low as 10(-7) M and required 20 min prior incubation with platelet suspension in order to inhibit aggregation by ADP. All the steps in ADP induced but not collagen induced platelet activation, viz. hydrolysis of phosphatidyl inositol, phosphorylation of 20, 47 and 250 kDa proteins as well as increased association of actin with Triton X-100 insoluble cytoskeletal matrix were inhibited by RA. RA when used as an agent for differentiation induction of cell progenitor is likely to affect the platelet aggregation and thereby the haemostatic process.     

Acute effects of heat on neuropsychological changes and physiological responses under noise condition

To examine the effects of heat and noise individually and jointly on certain physiological responses and cognitive and neuromotor based functions, 12 male participants were tested under 6 experimental conditions which resulted by combining 3 levels of heat (25 degrees, 30 degrees and 35 degrees C) and 2 levels of white noise (70 and 100 dB). The experiment was carried out in a controlled climatic chamber following two 6 x 6 latin square designs. The results indicated elevations in heart rate, oxygen uptake and body temperature due to the independent effect of heat or the combined effects of heat and noise. The independent action of noise was found to be depressive on the first two responses. On the neuropsychological effects, the heat adversely affected the speed in card sorting (by design configuration) and digit symbol tests, and also the accuracy and error rate in the reasoning ability test. The noise caused performance improvements in critical flicker frequency (simultaneous) and in error rates in card sorting (by design configuration). The combined effects of heat and noise indicated higher error rates in card sorting (by face value), decreased accuracy in reasoning ability and improvements in performance in accuracy scores and error rates in digit symbol test.