Petra Dolenec

A single dose of PPARγ agonist pioglitazone reduces cortical oxidative damage and microglial reaction following lateral fluid percussion brain injury in rats

Neuroprotective actions of the peroxisome proliferator-activated receptor-γ (PPARγ) agonists have been observed in various animal models of the brain injuries. In this study we examined the effects of a single dose of pioglitazone on oxidative and inflammatory parameters as well as on neurodegeneration and the edema formation in the rat parietal cortex following traumatic brain injury (TBI) induced by the lateral fluid percussion injury (LFPI) method. Pioglitazone was administered in a dose of 1mg/kg at 10min after the brain trauma. The animals of the control group were sham-operated and injected by vehicle. The rats were decapitated 24h after LFPI and their parietal cortices were analyzed by biochemical and histological methods. Cortical edema was evaluated in rats sacrificed 48h following TBI. Brain trauma caused statistically significant oxidative damage of lipids and proteins, an increase of glutathione peroxidase (GSH-Px) activity, the cyclooxygenase-2 (COX-2) overexpression, reactive astrocytosis, the microglia activation, neurodegeneration, and edema, but it did not influence the superoxide dismutase activity and the expressions of interleukin-1 beta, interleukin-6 and tumor necrosis factor-alpha in the rat parietal cortex. Pioglitazone significantly decreased the cortical lipid and protein oxidative damage, increased the GSH-Px activity and reduced microglial reaction. Although a certain degree of the TBI-induced COX-2 overexpression, neurodegeneration and edema decrease was detected in pioglitazone treated rats, it was not significant. In the injured animals, cortical reactive astrocytosis was unchanged by the tested PPARγ agonist. These findings demonstrate that pioglitazone, administered only in a single dose, early following LFPI, reduced cortical oxidative damage, increased antioxidant defense and had limited anti-inflammatory effect, suggesting the need for further studies of this drug in the treatment of TBI.

Temporal Pattern of Neurodegeneration, Programmed Cell Death, and Neuroplastic Responses in the Thalamus After Lateral Fluid Percussion Brain Injury in the Rat

Abstract The effects of traumatic brain injury (TBI) on the thalamus are not well characterized. We analyzed neuronal degeneration and loss, apoptosis, programmed cell death–executing pathways, and neuroplastic responses in the rat thalamus during the first week after lateral fluid percussion injury (LFPI). The most prominent neurodegenerative and neuroplastic changes were observed in the region containing the posterior thalamic nuclear group and ventral posteromedial and posterolateral thalamic nuclei ipsilateral to the LFPI. There was progressive neurodegeneration in these regions, with maximal neuronal loss on Day 7. Increases in numbers of apoptotic cells were detected on Day 1 and were enhanced on Days 3 and 7 after TBI. There was unchanged expression of active caspase-3 at all postinjury time points, but there was increased expression of apoptosis-inducing factor (AIF) on Day 7. The AIF nuclear translocation was detected on Day 1 and was maximal on Day 7. Total thalamic synaptophysin expression was unchanged, but immunostaining intensities were increased at all time points after TBI. Decreased growth-associated protein-43 expression and signal intensity were observed on Day 1. Our results suggest that progressive neuronal damage and loss, AIF signaling pathway–dependent programmed cell death, and limited neuroplastic changes occur in the rat thalamus during the first week after LFPI induction.

Spring migration characteristics of the House Martin, Delichon urbica (Aves: Hirundinidae) in Croatia: A response to climate change?

Many authors have discussed use of birds (and other organisms) as sensitive biomonitors for climate change. In this paper we investigate the long-term trends in first arrival dates of the long-distance migratory House Martin, Delichon urbica (Linneus, 1758), in north-western Croatia during the 28-year period. The aim of this paper is to identify possible relationship between arrival times and local spring air temperatures. Between 1981 and 2008 the House Martin arrived progressively earlier (5.9 days), probably in response to climate change. First arrival dates correlated significantly with increasing March-April mean temperatures. Correlation between mean spring air temperature and yearly temperatures were also statistically significant. Our results suggest that the arrival timing of the House Martin is influenced by spring air temperatures

Intra-seasonal changes in reproductive strategy of a multi-brooded passerine: the tree sparrow Passer montanus

In order to evaluate how a multi-brooded bird species adapts its breeding strategy during the breeding season, we investigated variations in clutch size, egg traits and sex of the final eggs in a population of the tree sparrow Passer montanus in northwestern Croatia. Of the three clutches of the season, the second was the largest and it contained the largest eggs. Furthermore, the females followed the brood survivor strategy for the second clutch, while they chose the brood reduction strategy for the first and the third clutches. These results indicate that female tree sparrows adjusted their reproductive strategy over the course of the breeding season and invested the most resources in the second clutch. We hypothesise that their decisions may serve to maximise the number of offspring that they can successfully rear in a single breeding season.