Roberto Cozzolino

Effects of concomitant nicotinic and muscarinic blockade on spatial memory disturbance in rats are purely additive: Evidence from the morris water task

This study reexamined the role played by a concurrent manipulation of nicotinic and muscarinic acetylcholine (ACh) receptors on performance of rats in the Morris water maze. A series of experiments was performed to test decreasing doses of scopolamine, a muscarinic ACh blocker, given concurrently with a fixed dose level of mecamylamine, a nicotinic ACh blocker, down to a subthreshold combination. Both substances were also tested separately. Data were analyzed to distinguish between a summative and a greater than additive (synergistic) effect of the two blocking agents. Our results fully support the important role played by ACh systems on cognitive functions and also show the substantial functional independence of the two ACh receptors in regulating spatial learning processes. In fact, data analysis did not reveal any significant interaction between the two ACh receptor blockers other than their additive effect: the hypothesis of a reciprocal modulation between the two ACh receptors, raised by some authors, cannot be supported for spatial learning mechanisms, at least with regard to the Morris water maze paradigm.

WITHIN- AND BETWEEN-STRAIN VARIABILITY IN LONGEVITY OF INBRED AND OUTBRED RATS UNDER THE SAME ENVIRONMENTAL CONDITIONS

Abstract The analysis of 26 longevity curves of different populations of inbred (Fischer 344) and outbred (Sprague-Dawley) rats highlighted a remarkable between-populations variability in survival parameters. This variability is independent of the breeding characteristics of the strain. The two strains differed in the slope of the survival curves, with Fischer 344 rats showing a higher survival over the second year of life as well as a lower interindividual variability. A model-free approach based on principal component analysis allowed us to quantify these differences and to highlight some limitations of the classical Gompertzian approach.

Maternal exposure to environmental enrichment before and during gestation influences behaviour of rat offspring in a sex-specific manner

The beneficial effects of Environmental Enrichment (EE) applied immediately after weaning or even in adulthood have been widely demonstrated. Less is known about the possible changes in behaviour and brain development of the progeny following the exposure of dams to EE. In order to further investigate this matter, female rats were reared in EE for 12weeks, from weaning until delivery. After having confirmed the presence of relevant behavioural effects of EE, both control and EE females underwent mating. Maternal behaviour was observed and male and female offspring were then administered a battery of behavioural test at different ages. EE mothers showed a decreased frequency of total nursing and, during the first 2days of lactation, an increase in licking/grooming behaviour. Maternal exposure to EE affected offspring behaviour in a sex-specific manner: social play behaviour and anxiety-like behaviour were increased in males but not in females and learning ability was improved only in females. As a general trend, maternal EE had a marked influence on motility in male and female offspring in both locomotor activity and swimming speed. Overall, this study highlights the importance of environmental stimulation, not only in the animals directly experiencing EE, but for their progeny too, opening the way to new hypothesis on the heritability mechanisms of behavioural traits.

Nonparametric scaling: A descriptive index

A descriptive index (CI) based on the U statistic is presented. The CI permits to quantify the differences between experimental samples taking into account both the location and variability features of the data without any distributional assumption. This index can be useful to build activity scales for series of compounds.