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Biomedical subjects

W M Robertson

Publications and source records attributed to W M Robertson.

23 records · Page 2Linked to original sources
PubMed1983

Hyposensitivity to serotonergic stimulation in protein malnourished rats.

Rats subjected to early protein malnutrition have higher levels of brain serotonin (5-HT) than well-nourished rats. In the present study we asked whether the elevated 5-HT levels of associated with any changes in sensitivity to serotonergic stimulation. In four different behavioral tets the effects of the 5-HT agonist N,N-dimethyltryptamine (DMT) were, with only a few exceptions, smaller in rats malnourished during both pre- and postweaning stages of development or during just one period or the other. In Experiment 1 the 5-HT syndrome induced by DMT was weaker in malnourished rats than in well-nourished ones. In Experiments 2 and 3, DMT was not a disruptive to malnourished rats in two motor tasks, rotating rod and treadmill, as it was to rats reared under high protein conditions. In Experiment 4 reductions in acoustic startle amplitudes induced by DMT were not as large in malnourished as in well-nourished rats. The hyposensitivity to DMt in protein malnourished rats may reflect a diminished sensitivity of 5-HT receptors resulting from the abnormally high levels of the neurotransmitter.

Animals↗
PubMed1982

Nuclear changes induced by the nematodes Xiphinema diversicaudatum and Longidorus elongatus in root-tips of perennial ryegrass, Lolium perenne.

The DNA content and size of individual nuclei from galls of perennial ryegrass root-tips induced by X. diversicaudatum and L. elongatus were measured. Feeding by X. diversicaudatum increased the DNA content of the nuclei by varying amounts. No regular doubling pattern of the DNA content was discernible. The DNA values varied up to between 32-64C. Generally the size of the nuclei was not increased, although some were larger than control nuclei. The modified nuclei probably have an altered metabolic function, which increases the food value of the gall to the nematode. Some bi-nucleate cells were also observed, which probably result from mitosis without cytokinesis. A preliminary examination of nuclei from galls induced by L. elongatus revealed similar nuclear changes, but no bi-nucleate cells were found.

Animals↗
PubMed1979

The effects of protein malnutrition on the behavior of rats during the suckling period.

Observations of 2 groups of dams and their litters were made every 3 hr around the clock on Days 1-20 postpartum. The dams fed either an 8% or a 25% casein diet for 5 weeks before mating and during gestation and lactation. Dams on the low protein diet spent more time in the nest actively nursing their young than did high protein dams, and they exhibited no deficits in other maternal behaviors. Five of 11 kinds of behavior developed more slowly in the undernourished pups than in the well-nourished ones, but the developmental delays were no longer than a few days. Circadian fluctuations were apparent in all of the pups' activities during the 3rd postnatal week as well as in grooming and horizontal movement, 2 behaviors that were present earlier, by 6-10 days of age.

Animal Population Groups↗