Surfactant aggregation in rat lungs: influence of temperature and ventilation

We examined the effect of the ventilatory rate and the temperature of excised lungs and of increased body temperature of anesthetized spontaneously breathing rats on the centrifugal sedimentation of disaturated phosphatidylcholine (DSPC) present in lung lavage returns. More DSPC sedimented from lungs ventilated at low than at high rates, and sedimentation of DSPC and lung volume loss were temperature dependent, 41 greater than 37 greater than 4 degrees C. Most of the noncellular sedimented material was tubular and common myelin; these had diminished ability to lower surface tension rapidly compared with less-aggregated surfactant. More aggregated DSPC accumulated and lung volume decreased more in spontaneously breathing rats anesthetized for 30 min than in rats killed immediately after being anesthetized; these changes were greater after 30 min of anesthesia in hyperthermic rats (40.4 +/- 0.3 degrees C) than in normothermic rats (37.4 +/- 0.1 degrees C). These studies have shown a correlation between the increased accumulation of surfactant as large aggregates and the loss of alveolar stability; however, a cause and effect between these events has not yet been shown.     

Protective effect of lung inflation in reperfusion-induced lung microvascular injury

We used the isolated-perfused rat lung model to study the influence of pulmonary ventilation and surfactant instillation on the development of postreperfusion lung microvascular injury. We hypothesized that the state of lung inflation during ischemia contributes to the development of the injury during reperfusion. Pulmonary microvascular injury was assessed by continuously monitoring the wet lung weight and measuring the vessel wall (125)I-labeled albumin ((125)I-albumin) permeability-surface area product (PS). Sprague-Dawley rats (n = 24) were divided into one control group and five experimental groups (n = 4 rats per group). Control lungs were continuously ventilated with 20% O(2) and perfused for 120 min. All lung preparations were ventilated with 20% O(2) before the ischemia period and during the reperfusion period. The various groups differed only in the ventilatory gas mixtures used during the flow cessation: group I, ventilated with 20% O(2); group II, ventilated with 100% N(2); group III, lungs remained collapsed and unventilated; group IV, same as group III but pretreated with surfactant (4 ml/kg) instilled into the airway; and group V, same as group III but saline (4 ml/kg) was instilled into the airway. Control lungs remained isogravimetric with baseline (125)I-albumin PS value of 4.9 +/- 0.3 x 10(-3) ml x min(-1) x g wet lung wt(-1). Lung wet weight in group III increased by 1.45 +/- 0.35 g and albumin PS increased to 17.7 +/- 2.3 x 10(-3), indicating development of vascular injury during the reperfusion period. Lung wet weight and albumin PS did not increase in groups I and II, indicating that ventilation by either 20% O(2) or 100% N(2) prevented vascular injury. Pretreatment of collapsed lungs with surfactant before cessation of flow also prevented the vascular injury, whereas pretreatment with saline vehicle had no effect. These results indicate that the state of lung inflation during ischemia (irrespective of gas mixture used) and supplementation of surfactant prevent reperfusion-induced lung microvascular injury.     

Differential effect of adrenalectomy on rat liver metallothionein mRNA levels in basal and stress conditions.

Liver metallothionein (MT) mRNA and serum MT levels of adrenalectomized (ADX) and sham-ADX rats in basal and stress (1, 3 or 6 h of restraint) conditions have been measured. Serum MT levels were overall lower in ADX than in sham-ADX rats. Basal liver MT mRNA levels were increased in ADX rats, suggesting that glucocorticoids have an inhibitory role on the regulation of liver MT synthesis. In contrast, liver MT mRNA levels were increased by stress in sham-ADX but not in ADX rats, suggesting a stimulatory role for glucocorticoids. These results suggest that glucocorticoids have a different role in liver MT regulation depending on the physiological situation.     

Impaired pulmonary defense against Pseudomonas aeruginosa in VEGF gene inactivated mouse lung

Repeated bacterial and viral infections are known to contribute to worsening lung function in several respiratory diseases, including asthma, cystic fibrosis, and chronic obstructive pulmonary disease (COPD). Previous studies have reported alveolar wall cell apoptosis and parenchymal damage in adult pulmonary VEGF gene ablated mice. We hypothesized that VEGF expressed by type II cells is also necessary to provide an effective host defense against bacteria in part by maintaining surfactant homeostasis. Therefore, Pseudomonas aeruginosa (PAO1) levels were evaluated in mice following lung‐targeted VEGF gene inactivation, and alterations in VEGF‐dependent type II cell function were evaluated by measuring surfactant homeostasis in mouse lungs and isolated type II cells. In VEGF‐deficient lungs increased PAO1 levels and pro‐inflammatory cytokines, TNFα and IL‐6, were detected 24 h after bacterial instillation compared to control lungs. In vivo lung‐targeted VEGF gene deletion (57% decrease in total pulmonary VEGF) did not alter alveolar surfactant or tissue disaturated phosphatidylcholine (DSPC) levels. However, sphingomyelin content, choline phosphate cytidylyltransferase (CCT) mRNA, and SP‐D expression were decreased. In isolated type II cells an 80% reduction of VEGF protein resulted in decreases in total phospholipids (PL), DSPC, DSPC synthesis, surfactant associated proteins (SP)‐B and ‐D, and the lipid transporters, ABCA1 and Rab3D. TPA‐induced DSPC secretion and apoptosis were elevated in VEGF‐deficient type II cells. These results suggest a potential protective role for type II cell‐expressed VEGF against bacterial initiated infection. J. Cell. Physiol. 228: 371–379, 2013. © 2012 Wiley Periodicals, Inc.     

Dexamethasone increases adult rat lung surfactant lipids

Prenatal administration of glucocorticoids stimulates epithelial cell maturation and induces a precocious development of pulmonary surfactant. The response of the adult lung to steroid administration is less well understood. We administered dexamethasone (2 mg X kg-1 X day-1) to adult male rats for 1 wk by daily subcutaneous injection. After pentobarbital anesthesia we lavaged the lungs and also isolated lamellar bodies from the tissue. Lipid analyses of the extracellular and intracellular surfactant compartments showed two- to fourfold greater amounts of total phospholipids and disaturated phosphatidylcholine compared with control. These changes were not found in kidney nor liver and were not present in plasma membrane, mitochondrial, or microsomal fractions from lungs. Morphometric analyses of the type II cells showed that anatomic measures of the lamellar body pool did not increase. We conclude that glucocorticoids have a significant effect to increase lung surfactant lipid pools of adult rat lungs by changing the phospholipid content of lamellar bodies, without changing lamellar body volume.     

Induction of intra- and extra-cellular phospholipids in the lungs of rats exposed to silica.

Intracellular and extracellular compartments of phospholipids in the lungs of rats were examined 28 days after intratracheal injection of silica (200 mg/kg). All compartments containing phospholipids were elevated, but the largest increases were seen in the intracellular and extracellular pulmonary surfactant. Intracellular pulmonary surfactant increased 123-fold from 1.18 +/- 0.65 to 144.9 +/- 53.8 and the extracellular surfactant increased 22-fold from 1.17 +/- 0.04 to 25.1 +/- 7.1 mg per pair of rat lungs respectively. The phospholipid composition of intracellular and extracellular surfactant did not change in response to silica, except for an almost 2-fold increase in the percentage of total phosphatidylinositol in both compartments. The phospholipid content of the lungs increased from 24.9 +/- 4.6 to 268.6 +/- 20.8 mg, with the intracellular and extracellular surfactant accounting for 59.1 and 24.6% of this total increase respectively. These data demonstrate that the major increases in the phospholipid content of the lungs induced by silica is associated with the pulmonary-surfactant system.     

CO2 relaxes parenchyma in the liquid-filled rat lung.

CO(2) regulation of lung compliance is currently explained by pH- and CO(2)-dependent changes in alveolar surface forces and bronchomotor tone. We hypothesized that in addition to, but independently of, those mechanisms, the parenchyma tissue responds to hypercapnia and hypocapnia by relaxing and contracting, respectively, thereby improving local matching of ventilation (Va) to perfusion (Q). Twenty adult rats were slowly ventilated with modified Krebs solution (rate = 3 min(-1), 37 degrees C, open chest) to produce unperfused living lung preparations free of intra-airway surface forces. The solution was gassed with 21% O(2), balance N(2), and CO(2) varied to produce alveolar hypocapnia (Pco(2) = 26.1 +/- 2.4 mmHg, pH = 7.56 +/- 0.04) or hypercapnia (Pco(2) = 55.0 +/- 2.3 mmHg, pH = 7.23 +/- 0.02). The results show that lung recoil, as indicated from airway pressure measured during a breathhold following a large volume inspiration, is reduced approximately 30% when exposed to hypercapnia vs. hypocapnia (P < 0.0001, paired t-test), but stress relaxation and flow-dependent airway resistance were unaltered. Increasing CO(2) from hypo- to hypercapnic levels caused a substantial, significant decrease in the quasi-static pressure-volume relationship, as measured after inspiration and expiration of several tidal volumes, but hysteresis was unaltered. Furthermore, addition of the glycolytic inhibitor NaF abolished CO(2) effects on lung recoil. The results suggest that lung parenchyma tissue relaxation, arising from active elements in response to increasing alveolar CO(2), is independent of (and apparently in parallel with) passive tissue elements and may actively contribute to Va/Q matching.     

Effects of intratracheal instillation of TNF-alpha on surfactant metabolism.

Tumor necrosis factor-alpha (TNF-alpha) has been shown to play an integral role in the pathogenesis of the acute respiratory distress syndrome. This disorder is characterized by a deficiency of alveolar surfactant, a surface-active material that is composed of key hydrophobic proteins and the major lipid disaturated phosphatidylcholine (DSPC). We investigated how TNF-alpha might alter DSPC content in rat lungs by instilling the cytokine (2.5 microg) intratracheally for 10 min and then assaying parameters of DSPC synthesis and degradation in alveolar type II epithelial cells, which produce surfactant. Cells isolated from rats given TNF-alpha had 26% lower levels of phosphatidylcholine compared with control. TNF-alpha treatment also decreased the ability of these cells to incorporate [(3)H]choline into DSPC by 45% compared with control isolates. There were no significant differences in the levels of choline substrate or choline transport between the groups. However, TNF-alpha produced a 64% decrease in the activity of cytidylyltransferase, the rate-regulatory enzyme required for DSPC synthesis. TNF-alpha administration in vivo also tended to stimulate phospholipase A(2) activity, but it did not alter other parameters for DSPC degradation such as activities for phosphatidylcholine-specific phospholipase C or phospholipase D. These observations indicate that TNF-alpha decreases the levels of surfactant lipid by decreasing the activity of a key enzyme involved in surfactant lipid synthesis. The results do not exclude stimulatory effects of the cytokine on phosphatidylcholine breakdown.     

Altered lung phospholipid metabolism in mice with targeted deletion of lysosomal-type phospholipase A2

Lung surfactant dipalmitoylphosphatidylcholine (DPPC) is endocytosed by alveolar epithelial cells and degraded by lysosomal-type phospholipase A2 (aiPLA2). This enzyme is identical to peroxiredoxin 6 (Prdx6), a bifunctional protein with PLA2 and GSH peroxidase activities. Lung phospholipid was studied in Prdx6 knockout (Prdx6-/-) mice. The normalized content of total phospholipid, phosphatidylcholine (PC), and disaturated phosphatidylcholine (DSPC) in bronchoalveolar lavage fluid, lung lamellar bodies, and lung homogenate was unchanged with age in wild-type mice but increased progressively in Prdx6-/- animals. Degradation of internalized [3H]DPPC in isolated mouse lungs after endotracheal instillation of unilamellar liposomes labeled with [3H]DPPC was significantly decreased at 2 h in Prdx6-/- mice (13.6 +/- 0.3% vs. 26.8 +/- 0.8% in the wild type), reflected by decreased dpm in the lysophosphatidylcholine and the unsaturated PC fractions. Incorporation of [14C]palmitate into DSPC at 24 h after intravenous injection was decreased by 73% in lamellar bodies and by 54% in alveolar lavage surfactant in Prdx6-/- mice, whereas incorporation of [3H]choline was decreased only slightly. Phospholipid metabolism in Prdx6-/- lungs was similar to that in wild-type lungs treated with MJ33, an inhibitor of aiPLA2 activity. These results confirm an important role for Prdx6 in lung surfactant DPPC degradation and synthesis by the reacylation pathway.     

Stimulation of surfactant phospholipid biosynthesis in the lungs of rats treated with silica.

The effects of intratracheally instilled silica (10 mg/rat) on the biosynthesis of surfactant phospholipids was investigated in the lungs of rats. The sizes of the intracellular and extracellular pools of surfactant phospholipids were measured 7, 14 and 28 days after silica exposure. The ability of lung slices to incorporate [14C]choline and [3H]palmitate into surfactant phosphatidylcholine (PC) and disaturated phosphatidylcholine (DSPC) was also investigated. Both intra- and extra-cellular pools of surfactant phospholipids were increased by silica treatment. The intracellular pool increased linearly over the 28-day time period, ultimately reaching a size 62-fold greater than controls. The extracellular pool also increased, but showed a pattern different from that of the intracellular pool. The extracellular pool increased non-linearly up to 14 days, and then declined. At its maximum, the extracellular pool was increased 16-fold over the control. The ability of lung slices to incorporate phospholipid precursors into surfactant-associated PC and DSPC was elevated at all time periods. The rate of incorporation of [14C]choline into surfactant PC and DSPC was maximal at 14 days and was nearly 3-fold greater than the rate in controls. The rate of incorporation of [3H]palmitate was also maximal at 14 days, approx. 5-fold above controls for PC and 3-fold for DSPC. At this same time point, the microsomal activity of cholinephosphate cytidylyltransferase was increased 4.5-fold above controls, but cytosolic activity was not significantly affected by silica treatment. These data indicate that biosynthesis of surfactant PC is elevated after treatment of lungs with silica and that this increased biosynthesis probably underlies the expansion of the intra- and extra-cellular pools of surfactant phospholipids.     

Lung mechanics, cellularity, and surfactant after prenatal starvation in guinea pigs

Prenatal starvation in the guinea pig causes reduced pulmonary diffusing capacity and retarded alveolarization among neonates. To study the impact of such starvation on biochemical and mechanical properties of the neonatal lung, pregnant guinea pigs were fed ad libitum throughout gestation or starved with 50% rations during their last trimester. Neonatal body weight was 35% less due to starvation, and dry lung weight, DNA, and protein contents were decreased 26, 36, and 31%, respectively (P less than 0.001 for all). Hematological data indicated no anemia, hypoproteinemia, or altered glucocorticoid levels due to starvation. Total surfactant phospholipids in these neonates were reduced 61% in lavage and 35% in the neonatal lung tissue, although surfactant compositions were similar to controls. Specific lung compliance in the air-filled lungs was not altered, but the saline-filled lungs were more distensible over deflation pressures of 9-18 cmH2O (transpulmonary). Although starvation retarded both lung cellularity and surfactant, only that portion of lung elastic recoil attributable to tissue forces was affected.     

A comparative study of postpneumonectomy compensatory lung response in growing male and female rats.

Postpneumonectomy compensatory lung response and normal lung growth in the early postnatal period were studied in male and female rats. Four-week-old litter-matched male and female Sprague-Dawley rats were subjected to left pneumonectomy or sham operation and followed for 3 wk. In both sexes after pneumonectomy, lung weight (WL), lung volume (VL), alveolar surface area (Sw), total alveolar number (N(at)), and the amount of DNA and protein increased significantly. In both males and females, WL, VL, and Sw matched those of both lungs of the sham-operated group, but N(at) and the amount of DNA and protein did not. Female pneumonectomy and sham-operated rats were smaller in body weight than males. Absolute WL, VL, Sw, N(at), and the amount of DNA and protein were significantly lower, but specific parameters (per unit body weight) were significantly greater in females than in males. After pneumonectomy, the postcaval lobe increased most in volume (70 and 73% in males and females, respectively). Mean linear intercept and mean chord length of alveoli increased, and the number of alveoli per unit volume decreased more in the postcaval and middle lobes than in upper and lower lobes in both sexes. Postpneumonectomy, loss of elastic lung recoil was observed in females. We conclude that, in certain aspects (WL, VL), compensatory growth matched both lungs of controls, but in others (biochemical, morphometric) it did not. There was evidence of alveolar multiplication, but the dominant effect was enlargement of air spaces.(ABSTRACT TRUNCATED AT 250 WORDS)     

Oxygen-induced changes in pulmonary phospholipids in the rat.

The composition and synthesis of alveolar and lung tissue phospholipids were investigated in normal and oxygen-poisoned rat lungs. Sixty-hour exposure to oxygen increased the total amount of phospholipids in the endobronchial extracts and lung tissue. Phosphatidyl glycerol was identified in both endobronchial extracts and lung tissue. The amount of unsaturated fatty acids in surfactant lecithin and phosphatidyl glycerol was slightly increased in oxygen-poisoned lungs whereas the composition of phospholipids in the endobronchial extracts was not affected by oxygen. After intraperitoneal administration of [32P]phosphate the specific activities of surfactant lecithin and phosphatidyl glycerol were clearly lower in oxygen-treated animals whereas the specific activities of lung tissue lecithin and phosphatidyl glycerol remained unaffected. The synthesis of lecithin from [14C]methionine through N-methyltransferase pathway was markedly depressed in lung slices but increased in liver tissue taken from oxygen-poisoned rats and incubated under oxygen indicating a difference between lung and liver methyltransferase enzymes. In conclusion, the present work suggests impaired synthesis and removal of alveolar phospholipids in oxygen-poisoned rats.     

Lung mechanics and airway reactivity in sheep during development of oxygen toxicity

The causes of respiratory distress in O2 toxicity are not well understood. The purpose of this study was to better define the airway abnormalities caused by breathing 100% O2. Sheep were instrumented for measurements of dynamic compliance (Cdyn), functional residual capacity by body plethysmography (FRC), hemodynamics, and lung lymph flow. Each day Cdyn and FRC were measured before, during, and after the application of 45 min continuous positive airway pressure (CPAP) at 15 cmH2O. The amount of aerosol histamine necessary to reduce Cdyn 35% from baseline (ED35) was measured each day as was the response to aerosol metaproterenol. Cdyn decreased progressively from 0.083 +/- 0.005 (SE) 1/cmH2O at baseline to 0.032 +/- 0.004 l/cm H2O at 96 h of O2. Surprisingly, FRC did not decrease (1,397 +/- 153 ml at baseline vs. 1,523 +/- 139 ml at 96 h). The ED35 to histamine did not vary among days or from air controls. Metaproterenol produced a variable inconsistent increase in Cdyn. We also measured changes in Cdyn during changes in respiratory rate and static pressure-volume relationships in five other sheep. We found a small but significant frequency dependence of compliance and an increase in lung stiffness with O2 toxicity. We conclude that in adult sheep O2 toxicity reduces Cdyn but does not increase airway reactivity. The large reduction in Cdyn in O2 toxicity results from processes other than increased airway reactivity or reduced lung volume, and Cdyn decreases before the development of lung edema.     

Physiological characterization of variability in response to lung volume reduction surgery.

This paper examines potential physiological mechanisms responsible for improvement after lung volume reduction surgery (LVRS). In 25 patients (63 +/- 9 yr; 11 men, 14 women), spirometry [forced expiratory volume in 1 s (FEV(1)) and forced vital capacity (FVC)], lung volumes [residual volume (RV) and total lung capacity (TLC)], small airway resistance, recoil pressures, and respiratory muscle contractility (RMC) were measured before and 4-6 mo after LVRS. Data were interpreted to assess how changes in each component of lung mechanics affect overall function. Among responders (DeltaFEV(1) > or = 12%; 150 ml), improvement was primarily due to an increase in FVC, not to FEV(1)-to-FVC ratio. Among nonresponders, FEV(1), FVC, and RV/TLC did not change after surgery, although recoil pressure increased in both groups. Both groups experienced a reduction in RMC after LVRS. In conclusion, LVRS improves function in emphysema by resizing the lung relative to the chest wall by reducing RV. LVRS does not change airway resistance but decreases RMC, which attenuates the potential benefits of LVRS that are generated by reducing RV/TLC. Among nonresponders, recoil pressure increased out of proportion to reduced volume, such that no increase in vital capacity or improvement in FEV(1) occurred.     

Tissue and airway impedance of excised normal, senile, and emphysematous lungs.

We partitioned pulmonary resistance (RL) in excised normal, senile, and emphysematous human lungs at various distending pressures; peripheral resistance (Rp) was measured by means of retrograde catheters and lung tissue resistance (Rti) by means of pleural capsules. By subtracting Rp from RL and Rti from Rp, we obtained, respectively, central (Rcaw) and peripheral (Rpaw) airway resistance. We determined also lung volumes, the elastic recoil pressure-volume curve, and the forced expiratory volume in 1 s-to-vital capacity ratio (FEV1/VC). The functional data were related to morphometry: mean linear intercept (Lm), diameter (d), and density (n/cm2) of membranous bronchioles. In the three groups of lungs, Rti demonstrates a marked negative frequency dependence and increases with transplumonary pressure. In emphysematous lungs, the increase of RL is mainly due to an increase of Rpaw; in addition, Rcaw and Rti are higher than normal. In the group of senile lungs, airway resistances are within normal range, but Rti is slightly increased. FEV1/VC is related to Rpaw and elastic recoil pressure; Rpaw is related to d and n/cm2, and Rti is related to dynamic elastance and to Lm.     

Isoproterenol improves ability of lung to clear edema in rats exposed to hyperoxia.

Exposure of adult rats to 100% O(2) results in lung injury and decreases active sodium transport and lung edema clearance. It has been reported that beta-adrenergic agonists increase lung edema clearance in normal rat lungs by upregulating alveolar epithelial Na(+)-K(+)-ATPase function. This study was designed to examine whether isoproterenol (Iso) affects lung edema clearance in rats exposed to 100% O(2) for 64 h. Active Na(+) transport and lung edema clearance decreased by approximately 44% in rats exposed to acute hyperoxia. Iso (10(-6) M) increased the ability of the lung to clear edema in room-air-breathing rats (from 0.50 +/- 0.02 to 0.99 +/- 0. 05 ml/h) and in rats exposed to 100% O(2) (from 0.28 +/- 0.03 to 0. 86 +/- 0.09 ml/h; P < 0.001). Disruption of intracellular microtubular transport of ion-transporting proteins by colchicine (0. 25 mg/100 g body wt) inhibited the stimulatory effects of Iso in hyperoxia-injured rat lungs, whereas the isomer beta-lumicolchicine, which does not affect microtubular transport, did not inhibit active Na(+) transport stimulated by Iso. Accordingly, Iso restored the lung's ability to clear edema after hyperoxic lung injury, probably by stimulation of the recruitment of ion-transporting proteins (Na(+)-K(+)-ATPase) from intracellular pools to the plasma membrane in rat alveolar epithelium.     

Airway responsiveness to inhaled and intravenous carbachol in sheep: effect of airway mucus

Excessive airway mucus can alter both the mass and site of aerosol deposition, which, in turn, may affect airway responsiveness to inhaled materials. In six prone sheep, we therefore measured pulmonary airflow resistance (RL) and cumulative aerosol deposition during five standard breaths (AD5) at base line and 3 min after inhalation challenge with 2% carbachol in buffered saline (10 breaths, tidal volume = 500 ml) or after an intravenous loading dose of carbachol (3 micrograms/kg) followed by a constant infusion of 0.3 micrograms.kg-1.min-1 with and without instillation of 20 ml of a mucus simulant (MS) into the distal end of each of the main bronchi or 30 ml of MS into the right main bronchus only by means of a flexible fiber-optic bronchoscope. Before carbachol challenge, RL did not change with MS into either both lungs or one lung only. AD5 increased from 36 +/- 2% (SE) before to 42 +/- 2% after MS instillation into both lungs (P less than 0.05) but remained unchanged after MS into one lung. After carbachol inhalation, RL increased significantly by 154 +/- 20 before and 126 +/- 25% after MS into both lungs and 162 +/- 24 before and 178 +/- 31% after MS into one lung (P less than 0.05). When the percent increase in RL was normalized for total aerosol deposition (% delta RL/AD5), the normalized values were lower after MS (3.0 +/- 0.5) than before MS (4.4 +/- 0.3) into both lungs (P less than 0.05) but were not significantly different before and after MS into the right lung only.(ABSTRACT TRUNCATED AT 250 WORDS)     

Actions of PPARgamma agonism on adipose tissue remodeling, insulin sensitivity, and lipemia in absence of glucocorticoids

Peroxisome proliferator-activated receptor gamma (PPARgamma) agonists improve insulin sensitivity and lipemia partly through enhancing adipose tissue proliferation and capacity for lipid retention. The agonists also reduce local adipose glucocorticoid production, which may in turn contribute to their metabolic actions. This study assessed the effects of a PPARgamma agonist in the absence of glucocorticoids (adrenalectomy, ADX). Intact, ADX, and intact pair-fed (PF) rats were treated with the PPARgamma agonist rosiglitazone (RSG) for 2 wk. RSG increased inguinal (subcutaneous) white (50%) and brown adipose tissue (6-fold) weight but not that of retroperitoneal (visceral) white adipose tissue. ADX but not PF reduced fat accretion in both inguinal and retroperitoneal adipose depots but did not affect brown adipose mass. RSG no longer increased inguinal weight in ADX and PF rats but increased brown adipose mass, albeit less so than in intact rats. RSG increased cell proliferation in white (3-fold) and brown adipose tissue (6-fold), as assessed microscopically and by total DNA, an effect that was attenuated but not abrogated by ADX. RSG reduced the expression of the glucocorticoid-activating enzyme 11beta-hydroxysteroid dehydrogenase 1 (11beta-HSD1) in all adipose depots. RSG improved insulin sensitivity (reduction in fasting insulin and homeostasis model assessment of insulin resistance, both -50%) and triacylglycerolemia (-75%) regardless of the glucocorticoid status, these effects being fully additive to those of ADX and PF. In conclusion, RSG partially retained its ability to induce white and brown adipose cell proliferation and brown adipose fat accretion and further improved insulin sensitivity and lipemia in ADX rats, such effects being therefore independent from the PPARgamma-mediated modulation of glucocorticoids.