Intracerebroventricular Glucocorticoid Infusion in Normal Rats: Induction of Parasympathetic‐Mediated Obesity and Insulin Resistance

Objective: The aims of the present study were to determine whether increased body weight resulting from intracerebroventricular (ICV) glucocorticoid (dexamethasone) infusion in normal rats is associated, as in obesity, with changes in glucose metabolism and to investigate whether the parasympathetic nervous system is involved in the glucocorticoid‐induced effects. Research Methods and Procedures: Male Sprague–Dawley rats were infused with ICV dexamethasone (2.5 μg/d) or its vehicle for 2 days during which food intake, body weight, and basal insulinemia were measured. Euglycemic–hyperinsulinemic clamps associated with the labeled 2‐deoxyglucose technique were then performed to determine the total rate of glucose disappearance and the tissue glucose use indices. Similar experiments were carried out in vagotomized rats. Results: Two days of ICV glucocorticoid infusion in normal rats resulted in increases in food intake, body weight, basal insulinemia, and produced decreases in the insulin‐stimulated total rate of glucose disappearance, as well as in glucose use indices of all muscle types studied. None of these alterations was observed when glucocorticoid infusion was carried out in vagotomized rats. Discussion: These data show that central glucocorticoid infusion favors anabolic processes, such as feeding behavior, body weight gain, and insulin output, while promoting muscle insulin resistance. These effects seem to be mediated by an activation of the parasympathetic nervous system, because they all disappear when tested in vagotomized rats.     

Relative contributions of local and regional factors to species richness and total density of butterflies and moths in semi-natural grasslands

Metapopulation theory predicts that species richness and total population density of habitat specialists increase with increasing area and regional connectivity of the habitat. To test these predictions, we examined the relative contributions of habitat patch area, connectivity of the regional habitat network and local habitat quality to species richness and total density of butterflies and day-active moths inhabiting semi-natural grasslands. We studied butterflies and moths in 48 replicate landscapes situated in southwest Finland, including a focal patch and the surrounding network of other semi-natural grasslands within a radius of 1.5 km from the focal patch. By applying the method of hierarchical partitioning, which can distinguish between independent and joint contributions of individual explanatory variables, we observed that variables of the local habitat quality (e.g. mean vegetation height and nectar plant abundance) generally showed the highest independent effect on species richness and total density of butterflies and moths. Habitat area did not show a significant independent contribution to species richness and total density of butterflies and moths. The effect of habitat connectivity was observed only for total density of the declining butterflies and moths. These observations indicate that the local habitat quality is of foremost importance in explaining variation in species richness and total density of butterflies and moths. In addition, declining butterflies and moths have larger populations in well-connected networks of semi-natural grasslands. Our results suggest that, while it is crucial to maintain high-quality habitats by management, with limited resources it would be appropriate to concentrate grassland management and restoration to areas with well-connected grassland networks in which the declining species currently have their strongest populations. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Chromosome counts in the Carex flava complex (Cyperaceae) in Finland

Chromosome numbers from 17 Finnish populations of six taxa in the Carex flava complex were examined. Special attention was given to taxa claimed to be endemic to Fennoscandia. The meiotic counts for C. flava n = 30, C. viridula var. viridula n = 35 and var. pulchella n = 35 are in accordance with previous reports. The counts for C. jemtlandica n = 34, C. bergrothii n = 35, and C. kotilaini n = 34 are new. The hybrid C. flava × kotilaini reveals severely disturbed meiosis with many uni- and multivalents. The results are briefly discussed in relation to morphological data. Carex jemtlandica should evidently be included in C. lepidocarpa. Carex bergrothii and C. kotilaini belong to the polymorphic C. viridula , but the latter probably consitute a specific cytotype.     

Cystic fibrosis mutation ΔF508 in Finland: other mutations predominate

Summary The frequency of mutation ΔF508 was determined in all 20 Finnish cystic fibrosis (CF) families with living affected children (19 with pancreatic insufficiency). ΔF508 was detected in 18 out of 40 CF chromosomes (45%). At least two different mutations associated with pancreatic insufficiently have occurred in a rare haplotype defined by XV2c, CS.7, KM19 alleles 1 2 2. Geographical clustering of ΔF508 and other mutations suggested that a founder effect and genetic drift have influenced the frequency of mutations causing CF in Finland.     

Habitat-dependent and -independent plastic responses to social environment in the nine-spined stickleback (Pungitius pungitius) brain

The influence of environmental complexity on brain development has been demonstrated in a number of taxa, but the potential influence of social environment on neural architecture remains largely unexplored. We investigated experimentally the influence of social environment on the development of different brain parts in geographically and genetically isolated and ecologically divergent populations of nine-spined sticklebacks (Pungitius pungitius). Fish from two marine and two pond populations were reared in the laboratory from eggs to adulthood either individually or in groups. Group-reared pond fish developed relatively smaller brains than those reared individually, but no such difference was found in marine fish. Group-reared fish from both pond and marine populations developed larger tecta optica and smaller bulbi olfactorii than individually reared fish. The fact that the social environment effect on brain size differed between marine and pond origin fish is in agreement with the previous research, showing that pond fish pay a high developmental cost from grouping while marine fish do not. Our results demonstrate that social environment has strong effects on the development of the stickleback brain, and on the brain''s sensory neural centres in particular. The potential adaptive significance of the observed brain-size plasticity is discussed.     

Plasma leptin and thyroxine of mink (Mustela vison) vary with gender, diet and subchronic exposure to PCBs

Female minks (Mustela vison) fed diets based on freshwater, marine or mixed fish were exposed to 1 mg of polychlorinated biphenyls (PCBs) a day for 21 weeks. The plasma leptin and thyroxine concentrations and the glucose-6-phosphatase and glycogen phophorylase activities in the liver were measured at the end of the experiment. The plasma thyroxine concentrations were significantly higher in the group exposed to PCBs. The mean plasma leptin concentration and glucose-6-phosphatase activity was the highest in the group that had the lowest body-mass index (BMI). The glycogen phophorylase activity was the highest in the freshwater fish-control group. The results suggest that the amount of fat in the body of the female minks is not the only determinant of the plasma leptin levels, but the leptin levels seem to rise with a lowered BMI unlike in rodents or humans. The positive correlation between the leptin levels and the glucose-6-phosphatase activity suggests increased gluconeogenesis with high leptin levels. Subchronic exposure to PCBs seems to have no effect on the plasma leptin levels or the glucose-6-phophatase activities, but it elevates significantly the plasma thyroxine levels with a mechanism that remains unknown.