Short-course subcutaneous treatment with PQ Grass strongly improves symptom and medication scores in grass allergy.

BACKGROUND: A modified grass allergen subcutaneous immunotherapy (SCIT) product with MicroCrystalline Tyrosine and monophosphoryl lipid-A as an adjuvant system (Grass MATA MPL [PQ Grass]) is being developed as short-course treatment of grass-pollen allergic rhinitis (SAR) and/or rhinoconjunctivitis. We sought to evaluate the combined symptom and medication score (CSMS) of the optimized cumulative dose of 27,600 standardized units (SU) PQ Grass in a field setting prior to embarking on a pivotal Phase III trial. METHODS: In this exploratory, randomized, double-blind, placebo-controlled trial subjects were enrolled across 14 sites (Germany and the United States of America). Six pre-seasonal subcutaneous injections of PQ Grass (using conventional or extended regimens) or placebo were administered to 119 subjects (aged 18-65 years) with moderate-to-severe SAR with or without asthma that was well-controlled. The primary efficacy endpoint was CSMS during peak grass pollen season (GPS). Secondary endpoints included Rhinoconjunctivitis Quality of Life Questionnaire standardized (RQLQ-S) and allergen-specific IgG4 response. RESULTS: The mean CSMS compared to placebo was 33.1% (p = .0325) and 39.5% (p = .0112) for the conventional and extended regimens, respectively. An increase in IgG4 was shown for both regimens (p < .01) as well as an improvement in total RQLQ-S for the extended regimen (mean change -0.72, p = .02). Both regimens were well-tolerated. CONCLUSIONS: This trial demonstrated a clinically relevant and statistically significant efficacy response to PQ Grass. Unprecedented effect sizes were reached for grass allergy of up to ≈40% compared to placebo for CSMS after only six PQ Grass injections. Both PQ Grass regimens were considered equally safe and well-tolerated. Based on enhanced efficacy profile extended regime will be progressed to the pivotal Phase III trial.

Covariate analysis of QTc and T-wave morphology: new possibilities in the evaluation of drugs that affect cardiac repolarization.

This study adds the dimension of a T-wave morphology composite score (MCS) to the QTc interval-based evaluation of drugs that affect cardiac repolarization. Electrocardiographic recordings from 62 subjects on placebo and 400 mg moxifloxacin were compared with those from 21 subjects on 160 and 320 mg D,L-sotalol. T-wave morphology changes, as assessed by DeltaMCS, are larger after 320 mg D,L-sotalol than after 160 mg D,L-sotalol; and the changes associated with 160 mg D,L-sotalol are, in turn, larger than those associated with moxifloxacin and placebo. Covariate analyses of DeltaQTc and DeltaMCS showed that changes in T-wave morphology are a significant effect of D,L-sotalol. By contrast, moxifloxacin was found to have no significant effect on T-wave morphology (DeltaMCS) at any given change in QTc. This study offers new insights into the repolarization behavior of a drug associated with low cardiac risk vs. one associated with a high risk and describes the added benefits of a T-wave MCS as a covariate to the assessment of the QTc interval.

Neurocognition and its influencing factors in the treatment of schizophrenia-effects of aripiprazole, olanzapine, quetiapine and risperidone.

BACKGROUND: To examine influencing variables of neurocognition in patients with schizophrenia and to predict cognition during antipsychotic treatment. METHODS: Data were obtained from patients with an acute episode of schizophrenia participating in two double-blind and one open label trial comparing the effects of different atypical antipsychotics on cognition. In total, 129 patients were enrolled in this analysis. Cognitive function was assessed at admission, week 4 and 8. Efficacy and tolerability were assessed weekly using the Positive and Negative Syndrome Scale (PANSS) and the Simpson Angus Sale (SAS). Patients were treated with aripirazole, olanzapine, quetiapine and risperidone. Regression analysis including mixed effect models was performed. RESULTS: A significant improvement in all cognitive domains was observed from baseline to week 8. Regarding the antipsychotic treatment applied quetiapine seemed to achieve the most favourable cognitive improvement. Negative and depressive symptoms, the patient's age and the concomitant and antipsychotic treatment applied were observed to significantly influence and predict neurocognition. CONCLUSION: The results may indicate that schizophrenia is a static disorder with trait and state dependent cognitive components especially in the memory domains. The influence of negative and depressive symptoms should be considered in daily clinical routine.

Effect of aripiprazole on cognition in the treatment of patients with schizophrenia.

BACKGROUND: The aim of this study was to assess the cognitive effects of aripiprazole in inpatients with schizophrenia. METHODS: This was an investigator-initiated, open label eight-week trial evaluating 56 inpatients with the DSM-IV diagnosis of schizophrenia. Efficacy was assessed weekly using the Positive and Negative Syndrome Scale (PANSS) and tolerability was assessed each week using the Udvalg for Klinske Undersogelser side effect rating scale (UKU). Cognitive function was assessed at baseline, week 4 and week 8. RESULTS: Aripiprazole showed significant improvement in PANSS total score and all subscores between baseline and endpoint visit. The substance was very well tolerated. Patients improved significantly in verbal memory, reaction time and reaction quality/attention from baseline to week eight. Furthermore, mean z-values of individual cognitive domains summarized in a global cognitive index improved significantly from baseline to week eight. DISCUSSION: Our results suggest that aripiprazole provides a valuable treatment option for patients with schizophrenia.

Orthostatic hypotensive effect of antipsychotic drugs in Wistar rats by in vivo and in vitro studies of alpha1-adrenoceptor function.

RATIONALE: Many antipsychotics cause orthostatic hypotension possibly due to antagonist action on resistance vessel alpha1A-adrenoceptors (alpha1A-AR). OBJECTIVE: We have tested this possibility by determining in Wistar rats how the orthostatic hypotensive effect of several antipsychotic drugs compares with their affinity for adrenoceptors in mesenteric small arteries (MSA with mainly alpha1A-AR) and aorta (mainly alpha1D-AR). MATERIALS AND METHODS: Using a tilt setup, orthostatic hypotension was measured in anaesthetized rats for prazosin and the antipsychotics haloperidol, sertindole, risperidone, clozapine, ziprasidone, domperidone, olanzapine, and aripiprazole. For in vitro studies, segments of MSA and aorta were mounted on a wire myograph for isometric tension recording. Cumulative concentration-response curves were constructed to phenylephrine (PE) in the absence and presence of the drugs. Apparent affinity (pA2) was calculated by Schild analysis. RESULTS: Prazosin antagonized tilt-induced and PE responses in both studies (threshold 4 ng/ml, pA2 9.52 MSA, 10.1 aorta). The rank order of the potency of the antipsychotics in the tilt experiments correlated (r2 = 0.69, P = 0.01) with the pA2-values in MSA: Risperidone and sertindole had the highest potency in the tilt test (threshold 159 and 97 ng/ml) and the highest apparent affinity in MSA (pA2 8.92 and 8.78), in contrast with aripiprazole and domperidone, which had the lowest in each case (threshold 4.1 and 3.0 microg/ml, pA2 7.17 and 6.99). In aorta, the pA2 values did not correlate with the in vivo potencies; in particular, sertindole had no functional affinity in aorta. CONCLUSION: We conclude that the orthostatic hypotensive effect in rats of the antipsychotic drugs investigated is mediated through alpha1A-ARs.

Omalizumab provides long-term control in patients with moderate-to-severe allergic asthma.

The ability of omalizumab, an anti-immnoglobulin-E agent, to maintain long-term disease control in patients with moderate-to-severe allergic asthma was investigated in a 24-week double-blind extension to a 28-week core trial. During the extension, 483 of the initial 546 patients were maintained on randomised treatment and the lowest sustainable dose of beclomethasone dipropionate (BDP) as established during the steroid-reduction phase of the core trial. The use of concomitant asthma medication was permitted and investigators were allowed to adjust the BDP dose or switch patients from BDP to other asthma medications if deemed necessary. More omalizumab-treated patients (33.5%) than placebo-treated patients (13.5%) were able to complete the extension period without requiring inhaled corticosteroid treatment. The mean BDP equivalent dose throughout the extension was lower in the omalizumab group (25 microg x day(-1)) than in the placebo group (43 microg x day(-1)). Disease control was sustained in 76% of omalizumab patients compared with 59.4% of placebo patients free from an asthma exacerbation during the extension period. Compared with placebo, fewer patients in the omalizumab group used other concomitant asthma medication during the extension. Treatment with omalizumab was well tolerated and the incidence of adverse events was similar between groups. In conclusion, these results suggest that omalizumab is a promising new agent for the long-term control of allergic asthma.

Sertindole: cardiac electrophysiological profile.

QT interval prolongation is the ECG correlate of prolongation of the cardiac action potential (AP). Abnormal or excessive QT interval prolongation may be associated with an increased risk of ventricular tachycardia. This association appears increasingly evident in congenital long QT syndrome and with certain classes of cardiovascular and non-cardiovascular therapeutics. Almost all drugs causing QT interval prolongation inhibit the rapid component of the delayed rectifier potassium current (I Kr ), an ion channel involved in the termination of the myocardial AP. Inhibition of I Kr leads to AP and QT interval prolongation. Drugs, which do not encounter a sufficient electrophysiological counterbalance to the inhibitory effect on I Kr , may thus impose a risk of ventricular tachyarrhythmia. Some non-cardiac drugs, including the antipsychotic sertindole, have inhibitory effects on I Kr but, in contrast to the drugs that are known to cause tachyarrhythmia, sertindole possesses an important electrophysiological counterbalancing profile. Sertindole inhibits f 1 -adrenoceptors and blocks both sodium and calcium channels. The balanced electrophysiological profile of sertindole may well explain the low proarrhythmic potential observed in animal proarrhythmia models against positive comparators. It also supports the lack of increased cardiac mortality observed in clinical trials with sertindole and in large epidemiological studies.

The anti-IgE antibody omalizumab reduces exacerbations and steroid requirement in allergic asthmatics.

The clinical benefit and steroid-sparing effect of treatment with the anti-immunoglobulin-E (IgE) antibody, omalizumab, was assessed in patients with moderate-to-severe allergic asthma. After a run-in period, 546 allergic asthmatics (aged 12-76 yrs), symptomatic despite inhaled corticosteroids (500-1,200 microg daily of beclomethasone dipropionate), were randomized to receive double-blind either placebo or omalizumab every 2 or 4 weeks (depending on body weight and serum total IgE) subcutaneously for 7 months. A constant beclomethasone dose was maintained during a 16-week stable-steroid phase and progressively reduced to the lowest dose required for asthma control over the following 8 weeks. The latter dose was maintained for the next 4 weeks. Asthma exacerbations represented the primary variable. Compared to the placebo group, the omalizumab group showed 58% fewer exacerbations per patient during the stable-steroid phase (p<0.001). During the steroid-reduction phase, there were 52% fewer exacerbations in the omalizumab group versus the placebo group (p<0.001) despite the greater reduction of the beclomethasone dosage on omalizumab (p<0.001). Treatment with omalizumab was well tolerated. The incidence of adverse events was similar in both groups. These results indicate that omalizumab therapy safely improves asthma control in allergic asthmatics who remain symptomatic despite regular use of inhaled corticosteroids and simultaneous reduction in corticosteroid requirement.

Long-term asthma control with oral montelukast and inhaled beclomethasone for adults and children 6 years and older.

BACKGROUND: Leukotriene receptor antagonists have demonstrated clinical benefits in chronic asthma studies of up to 3 months in duration. The effects of these agents over extended periods of time have not been reported. OBJECTIVE: To describe the long-term effect of oral montelukast, a potent and specific cysteinyl leukotriene receptor antagonist, compared with inhaled corticosteroids in both adult and paediatric patients with chronic asthma. METHODS: Male and female patients with chronic, stable asthma (adults aged 15-85 years, children aged 6-14 years), who had completed double-blind, placebo-controlled clinical studies, participated in three extension studies with oral montelukast taken once daily (10 mg tablet for adults, 5 mg chewable tablet for paediatric patients) or inhaled corticosteroids (beclomethasone 200 microg twice daily for adults, beclomethasone 100 microg or equivalent three times daily for children). A double-blind adult extension study was 37 weeks in duration; open-label adult extension studies were 156 (adults) and 112 (paediatric) weeks in duration. A total of 436, 374, and 245 patients entered these extension studies, respectively. RESULTS: Treatment with both montelukast and inhaled corticosteroids resulted in improvement in multiple parameters of asthma control. Improvements in daytime symptom scores were generally comparable among treatment groups. No tachyphylaxis to the effects of montelukast was evident. In the adult open-label study, however, the effect of beclomethasone on mean forced expiratory volume in 1 second (FEV1) gradually decreased from start of the study to the end of the follow-up treatment period. CONCLUSION: Both montelukast and inhaled corticosteroids were effective in controlling mild to moderate chronic asthma; the relative effectiveness of montelukast and beclomethasone were similar in open-label conditions. The hypothesis, that clinical practice conditions (e.g., adherence) may have a significant impact on the effectiveness of these therapies, should be tested in future clinical trials.

Addition of salmeterol to low-dose fluticasone versus higher-dose fluticasone: an analysis of asthma exacerbations.

BACKGROUND: Adding salmeterol to low-dose fluticasone propionate (FP) produces greater improvements in pulmonary function and symptom control than increasing the dose of FP in patients who remain symptomatic with low-dose FP. OBJECTIVE: We sought to compare the rates and characteristics of asthma exacerbations in patients after adding salmeterol to low-dose FP with the rates and characteristics of exacerbations in patients receiving higher dose FP. METHODS: In 2 multicenter, double-blind studies, 925 patients 12 years of age and older receiving 88 microg twice daily FP randomly received either 42 microg of salmeterol and 88 microg of FP or an increased dose of FP (220 microg) twice daily for 24 weeks. Exacerbation rates and clinical measures of asthma worsening were assessed for all patients who experienced an asthma exacerbation. RESULTS: The addition of salmeterol resulted in a significantly lower rate and number of exacerbations compared with higher dose FP. A total of 41 (8.8%) patients experienced 47 exacerbations with the addition of salmeterol compared with 63 (13.8%) patients with 75 exacerbations in the group receiving increased-dose FP (P =.017). Salmeterol plus low-dose FP was significantly more protective than increased-dose FP in preventing asthma exacerbations, as assessed by the time to first exacerbation (P <.05). In both groups clinical indicators of worsening asthma showed parallel changes before asthma exacerbation, and greater improvements were observed after exacerbation with salmeterol compared with higher dose FP. CONCLUSION: Salmeterol plus low-dose FP was more effective than higher dose FP alone in reducing asthma exacerbations in patients with persistent asthma. The ability to detect deteriorating asthma and the severity of exacerbation was similar between groups.

Characteristics of the pulse waveform during altered nitric oxide synthesis in the rabbit.

Nitrovasodilators produce characteristic changes in the shape of the peripheral pulse wave. Similar changes might also be caused by alteration of endogenous NO activity, which would allow such activity to be assessed in vivo. We investigated whether manipulation of the NO pathway influences the pulse waveform, and the mechanisms involved. The pulse wave in the ear of normal rabbits was examined by reflectance photoplethysmography before and during infusion of vasoactive agents. Pulse wave velocity was assessed by using an additional sensor on the rear foot. A diastolic peak was observed in the ear pulse; its timing was consistent with it being a reflection of the systolic peak from the lower body. The height of the dicrotic notch marking the start of this diastolic wave was decreased by acetylcholine or an NO donor, and further decreased by a phosphodiesterase type V inhibitor. The acetylcholine-induced decreases were blocked by inhibiting NO synthesis with N(G)-nitro-L-arginine methyl ester (L-NAME) but were unaffected by the inactive enantiomer D-NAME. These data demonstrate that NO influences the height of the notch in the pulse wave. Heart rate and blood pressure were altered during acetylcholine or L-NAME infusion, but there were no changes in pulse wave amplitude or velocity, or in the timing of the diastolic peak or dicrotic notch. The slope of the pulse wave between the systolic peak and notch changed substantially. These effects are most convincingly explained by changes in wave reflection, not only from the lower body but also from more proximal sites.

In vivo muscarinic cholinergic mediated effects of Lu 25-109, a M1 agonist and M2/M3 antagonist in vitro.

Lu 25-109 [5-(2-ethyl-2H-tetrazol-5-yl)-1,2,3,6-tetrahydro-1-methylpyridine] , has M agonistic and M2/M3 antagonistic effects at muscarinic receptors in vitro; a pharmacological profile that may be beneficial in treatment of Alzheimer's disease. In the present study, we compare functional in vivo effects of Lu 25-109 and reference compounds in animal models of muscarinic cholinergic function. Lu 25-109 substituted completely for the discriminative stimulus effects of (-)-7-methyl-3-(2-propynyloxy)-4,5,6,7-tetrahydroisothiazolo -[4, 5-c]pyridine (Lu 26-046), a partial M1/M2 agonist, but only weakly for the effects of the non-selective M1/M2/M3 agonist 3-methoxy-4,5,6,7-tetrahydro-isoxazolo[4, 5-c] pyridine (O-Me-THPO). Lu 25-109 did not reverse O-Me-THPO-induced discriminative stimulus. Tacrine did not substitute for any of the training drugs. Lu 25-109 did not substitute in (-)-nicotine trained rats. Lu 25-109 did not antagonize oxotremorine-induced hypothermia, tremor and salivation in mice and antagonized physostigmine-induced lethality with low potency. Unlike non-selective muscarinic agonists and acetylcholinesterase inhibitors, Lu 25-109 did not induce hypothermia, tremor or salivation in mice. Spontaneous locomotor activity and motor co-ordination were inhibited only at high doses. Lu 25-109 had no effect on mean blood pressure in anaesthetized rats. Lu 25-109 and O-Me-THPO produced a significant increase in heart rate. The maximum increase was 37%. In anaesthetized cats, increasing i.v. doses of Lu 25-109 were without effect on the mean blood pressure, except for a short lasting (<2 min) depressor effect following the IV injection. Furthermore, Lu 25-109 did not attenuate the reflex mechanisms restoring blood pressure following orthostasis in cats. In conclusion, the drug discrimination studies suggest a unique activity profile of Lu 25-109, and the in vivo profile suggests none or a very low frequency of unwanted cholinergic mediated effects.

Montelukast for chronic asthma in 6- to 14-year-old children: a randomized, double-blind trial. Pediatric Montelukast Study Group.

CONTEXT: Leukotrienes are important mediators of asthma by causing bronchoconstriction, mucous secretion, and increased vascular permeability. Studies using compounds that block leukotrienes have demonstrated improvement in asthma control in adults and adolescents, but children younger than 12 years, for whom asthma is the most common chronic disease, have not been studied. OBJECTIVE: To determine the clinical effect of montelukast, a leukotriene receptor antagonist, in 6- to 14-year-old children with asthma. DESIGN: Eight-week, multicenter, randomized, double-blind study. SETTING: Forty-seven outpatient centers at private practices and academic medical centers in the United States and Canada. PATIENTS: A total of 336 children with forced expiratory volume in 1 second (FEV1) between 50% to 85% of the predicted value, at least 15% reversibility after inhaled beta-agonist administration, a minimal predefined level of daytime asthma symptoms, and daily beta-agonist use. Concomitant inhaled corticosteroids at a constant daily dose were used by 39% of patients receiving montelukast and 33% receiving placebo. INTERVENTION: After a 2-week placebo run-in period, patients received either montelukast (5-mg chewable tablet) or matching-image placebo once daily at bed-time for 8 weeks. MAIN OUTCOME MEASURE: Morning FEV1 percent change from baseline. RESULTS: Mean morning FEV1 increased from 1.85 L to 2.01 L in the montelukast group and from 1.85 L to 1.93 L in the placebo group. This represents an 8.23% (95% confidence interval [CI], 6.33% to 10.13%) increase from baseline in the montelukast group and a 3.58% (95% CI, 1.29% to 5.87%) increase from baseline in the placebo group (P<.001 for montelukast vs placebo). CONCLUSION: Montelukast improves morning FEV1 in 6- to 14-year-old children with chronic asthma.

Cold-induced heat shock protein expression in rat aorta and brown adipose tissue.

Recent reports indicate that Heat Shock Proteins (HSPs) are induced in mammalian tissues as part of a homeostatic response to environmental stressors. Administration of sympathomimetic drugs and neuroendocrine stress hormones has been shown to evoke an HSP response in unstressed animals indicating that cell signaling events exists that couple specific neurotransmitter/hormone-receptor interactions with HSP expression in mammalian tissues. Herein, we demonstrate that exposure of rats to a cold ambient temperature (6 degrees C) results in increased expression of constitutive and inducible members of the HSP70 gene family in association with increased expression of the mitochondrial uncoupling protein in brown adipose tissue (BAT). Increased HSP70 expression was not restricted to BAT because HSP70 was also induced in the aorta. This cold-induced HSP response is characterized by a transient increase in HSP70 protein and mRNA in both tissues during continued exposure. Ganglionic blockade prevented cold-induced HSP70 expression in BAT and aorta, indicating that sympathetic activity is requisite to this response. Administration of the alpha 1-adrenergic receptor antagonist, prazosin, also blocked expression, further delineating possible signaling mechanisms mediating this response. Apparently, cells in some mammalian tissues have adopted unique cellular regulatory mechanisms to support HSP induction that have been incorporated into the physiological response of the entire organism to an environmental stressor.

Adrenergic regulation of the heat shock response in brown adipose tissue.

One of several ways that cells respond to damage or stress is by the expression of a set of highly conserved proteins termed, heat shock proteins (HSP). Induction of the heat shock response has been positively correlated with adaptation or protection of cells and tissues from the destructive effects of various types of stressors. Although heat can induce a generalized HSP response in most cells, the selective induction of HSP in specific cell populations by pharmacological agents may prove therapeutically useful for the protection of organs or tissues at risk for damage. Results from our studies suggest that the HSP response is integrated with fundamental physiological stress responses and demonstrate that distinct regulatory events couple neurotransmitter/hormone-receptor interactions with HSP expression in mammalian tissues. We demonstrate that the adrenergic receptor agonist, phenylephrine, induces HSP expression in brown adipose tissue (BAT). Apparently, this response is mediated by alpha-adrenergic receptors in BAT because prazosin, but not propranolol, blocks HSP induction and hexamethonium is without effect. Based on the transcripts induced and the magnitude of heat shock element-binding activity, phenylephrine appears to induce HSP expression through unique transcriptional regulatory mechanisms. The phenylephrine-induced HSP response is not unique to BAT as we have found that HSP are induced in other tissues as well. In BAT, HSP may facilitate the thermogenic function of this tissue, however, their function in other tissues remains unclear. The results of this study characterize a model system where the heat shock response is differentially evoked by a specific pharmacological agent and may aide in the development of treatment strategies to selectively target HSP expression in vivo.

Investigation of endogenous nitric oxide vascular function in the carotid artery of cholesterol-fed rabbits.

1. The function of endogenous nitric oxide (NO) at the level of vascular smooth muscle, was assessed in a popular experimental model of accelerated atherosclerosis, the cholesterol-fed rabbit. 2. Endothelium-dependent vasorelaxation in response to acetylcholine (ACh, 1 microM) was significantly impaired in the carotid artery from rabbits maintained on a 1% (W/W) cholesterol diet for 8-10 weeks. Furthermore, the ability of an inhibitor of nitric oxide synthase (NOS), NG-nitro-L-arginine methyl ester (L-NAME, 1-300 microM), to enhance the contractile reactivity to a submaximal concentration of noradrenaline (NA, 3 microM), was significantly attenuated in hypercholesterolaemia. 3. A significant linear correlation between the maximal contractile effect of L-NAME (300 microM) and maximal vasorelaxation to ACh (1 microM) was determined in the carotid artery from control rabbits. In contrast, no such linear correlation was found in the carotid artery from hypercholesterolaemic rabbits. 4. We conclude that there are lesions both in agonist-stimulated, endogenous NO-dependent vasorelaxation and in the regulation of vasoconstrictor reactivity by endogenous NO in the hypercholesterolaemic rabbit carotid artery. Furthermore, the normal linear relationship between the contractile effect of L-NAME and vasorelaxation to ACh is lost after cholesterol-feeding.

Thermoregulatory and heat-shock protein response deficits in cold-exposed diabetic mice.

Cold-induced expression of heat-shock proteins (HSPs) has been suggested to facilitate thermogenesis in brown adipose tissue (BAT). However, the regulation of this response and the mechanism supporting this facilitation have not been established. Because of the significant role of insulin in maintaining BAT thermogenesis, we employed a transgenic mouse model of diabetes to investigate the regulation and function of HSPs in BAT thermogenesis. These transgenic mice overexpress a calmodulin minigene regulated by the rat insulin II promotor, resulting in severe diabetes characterized by elevated blood glucose and glucagon that coincides with reduced serum and pancreatic insulin. Body temperature (Tb) of diabetic mice dropped significantly faster during a 3-h cold exposure (6 degrees C) than Tb of similarly treated control littermates. Cold exposure resulted in increased levels of constitutive and inducible HSP70 transcripts in control mice, but only constitutive HSP70 mRNA transcripts were induced in diabetic mice. Diabetes did not affect uncoupling protein induction, but cold-induced expression of members of other HSP families was reduced. Correspondingly, heat-shock regulatory factors were not activated in diabetic mice even though these factors were present. Phenylephrine induced HSP70 expression in control and diabetic animals, indicating that alpha-receptor-coupled HSP induction remained intact in BAT of diabetic mice. Insulin replacement restored the Tb response of diabetic mice as well as the HSP response. From these results it is clear that physiological signals that regulate cold-induced activation of BAT also regulate HSP expression in this tissue. This diabetic model provides a novel system in which the HSP response to cold has been selectively knocked out, making it a useful tool for the study of HSP regulation and function in BAT.

Characterization and regulation of cold-induced heat shock protein expression in mouse brown adipose tissue.

The accumulation of heat shock proteins (HSPs) after the exposure of cells or organisms to elevated temperatures is well established. It is also known that a variety of other environmental and cellular metabolic stressors can induce HSP synthesis. However, few studies have investigated the effect of cold temperature on HSP expression. Here we report that exposure of Institute of Cancer Research (ICR) mice to cold ambient temperatures results in a tissue-selective induction of HSPs in brown adipose tissue (BAT) coincident with the induction of mitochondrial uncoupling protein synthesis. Cold-induced HSP expression is associated with enhanced binding of heat shock transcription factors to DNA, similar to that which occurs after exposure of cells or tissues to heat and other metabolic stresses. Adrenergic receptor antagonists were found to block cold-induced HSP70 expression in BAT, whereas adrenergic agonists induced BAT HSP expression in the absence of cold exposure. These findings suggest that norepinephrine, released in response to cold exposure, induces HSP expression in BAT. Norepinephrine appears to initiate transcription of HSP genes after binding to BAT adrenergic receptors through, as yet, undetermined signal transduction pathways. Thermogenesis results from an increase in activity and synthesis of several metabolic enzymes in BAT of animals exposed to cold challenge. The concomitant increase in HSPs may function to facilitate the translocation and activity of the enzymes involved in this process.