A comparison of the in vivo and in vitro response of mammalian embryos to a teratogenic insult

This study serves to further define the capabilities of the whole embryo culture system using the known teratogen, hydroxyurea (HU). An initial in vivo study was performed whereby day 9 pregnant mothers were injected i.p. with 300 mg/kg HU. Dams were sacrifice 2 days later and embryos were analyzed for malformations and total embryonic protein. In addition, the peak plasma value from injected dams was found to be approximately 300 μg/ml with a plasma half-life of 30min. These values were then reproduced in the culture system with results noted in cultured embryos with respect to the types of malformations found. Additional in vitro experiments were performed varying both exposure time and drug level concentrations. Results indicate that both of these parameters are important considerations when designing in vitro experiments.     

SSRI treatment decreases prolactin and hyperthermic responses to mCPP

We studied the effect of 3 weeks treatment with the selective serotonin re-uptake inhibitor (SSRI), paroxetine (30 mg daily), on the neuroendocrine and hyperthermic responses to the 5-HT_2C receptor agonist, m-chlorophenylpiperazine (mCPP) (0.05 mg/kg IV), in seven healthy volunteers. Following paroxetine treatment, both the prolactin and hyperthermic responses to mCPP were significantly attenuated. These data are consistent with experimental animal studies indicating that repeated SSRI treatment leads to a functional desensitisation of 5-HT_2C receptors. This effect may be linked to the anxiolytic properties of SSRIs. Received: 2 May 1997/Final version: 30 June 1997     

Neonatal exposure to chlorpyrifos affects maternal responses and maternal aggression of female mice in adulthood

CD-1 mice were exposed to the organophosphate pesticide chlorpyrifos (CPF) throughout postnatal days (PND) 11–14 at the subtoxic dose of 3 mg/kg. At adolescent age, females and males underwent a sociability test in which level of sociability and social preference were measured. At adulthood only females' behavior was analyzed. Maternal behavior of CPF-exposed females was assessed on postpartum day 1 after removal of the pups for 1 h, while anxiety levels were measured in a 5 min dark–light test on postpartum day 2. Nest defense response to an unfamiliar male intruder was assessed on postpartum day 7. In addition, from birth to postpartum day 7 a detailed analysis of nest building activity was carried out. Neonatal CPF exposure does not interfere with social behavior and social preferences at adolescence, whereas at adulthood it induces significant behavioral alterations in lactating females. Motivation to build and defend the nest was decreased in CPF females that were also less anxious than controls in the dark–light paradigm. These results confirm that developmental exposure to CPF induces long-lasting alterations in selected sexual-dimorphic responses of the adult social repertoire, and suggest that early exposure to CPF might interfere with hypothalamic neuroendocrine mechanisms regulating social responses.     

Embryonic cardiac arrhythmia and generation of reactive oxygen species: common teratogenic mechanism for IKr blocking drugs

In the adult organism, it is well established that hypoxia followed by reperfusion may be fatal and result in generation of reactive oxygen species (ROS) and subsequent tissue damage. There is also considerable evidence that temporary decrease or interruption in oxygen supply to the embryo and ROS generation during reperfusion result in tissue damage in embryonic tissues. A wide spectrum of different malformations by transient embryonic hypoxia could be produced, depending on the duration, extent, and timing of the hypoxic event. It is the contention of this paper that drugs that block the potassium channel IKr, either as an intended pharmacologic effect or as an unwanted side-effect, are potentially teratogenic by a common ROS related mechanism. Drugs blocking the IKr channel, such as almokalant, dofetilide, phenytoin, cisapride and astemizole, do all produce a similar pattern of hypoxia-related malformations. Mechanistic studies show that the malformations are preceded by embryonic cardiac arrhythmia and periods of hypoxia/reoxygenation in embryonic tissues. Pretreatment or simultaneous treatment with radical scavengers with capacity to capture ROS, markedly decrease the teratogenicity of different IKr blocking drugs. A second aim of this review is to demonstrate that the conventional design of teratology studies is not optimal to detect malformations caused by IKr blocking drugs. Repeated high doses result in high incidences of embryonic death due embryonic cardiac arrhythmia, thus masking their teratogenic potential. Instead, single dosing on specific days is proposed to be a better way to characterize the teratogenic potential of Ikr blocking drugs.     

Targeting heat shock response pathways to treat pancreatic cancer

Pancreatic cancer belongs to the group of extremely aggressive human cancers; conventional cancer treatments have little impact. Increasing understanding of the pathways associated with pancreatic cancer progression has enabled the development of targeted therapy on this cancer. Heat shock proteins (HSPs) and related heat shock response (HSR) pathways control multiple important oncogenic pathways for pancreatic cancer development. Consequently, they represent promising novel targets for pancreatic cancer therapy. Various strategies have been proposed and elaborated to target HSPs/HSR in pancreatic cancer with the corresponding modulators, the details of which are highlighted in this review.     

Specific cerebral heat shock proteins and histamine receptor cross-talking mechanisms promote distinct lead-dependent neurotoxic responses in teleosts

Recent interests are beginning to be directed towards toxic neurobiological dysfunctions caused by lead (Pb) in aquatic vertebrates. In the present work, treatment with a maximum acceptable toxic concentration of this heavy metal was responsible for highly significant (p<0.01) abnormal motor behaviors such as hyperactive movements in the teleost Thalassoma pavo and the same treatment accounted for significantly (p<0.05) enhanced hyperventilating states. On the other hand, greater abnormal motor behaviors were detected in the presence of the histamine (HA) receptor subtype 2 (H(2)R) antagonist cimetidine (Cim), as shown by the very robust (p<0.001) increases of the two behavioral states. Interestingly, elevated expression levels of stress-related factors, i.e. heat shock protein70/90 (HSP90/70) orthologs were reported for the first time in hypothalamic and mesencephalic areas of Pb-treated teleosts. In particular, an up-regulation of HSP70 was readily detected when this heavy metal was given concomitantly with Cim, while the histamine subtype 3 antagonist (H(3)R) thioperamide (Thio), instead, blocked Pb-dependent up-regulatory trends of both chaperones in mostly hypothalamic areas. Moreover, intense neuronal damages of the above brain regions coincided with altered expressions of HSP70 and HSP90 when treated only with Cim. Overall these first results show that distinct H(n)R are able to exert a net neuroprotective role arising from their interaction with chaperones in fish exposed to Pb-dependent stressful conditions making this a potentially key interaction especially for T. pavo, aquatic species which plays an important ecological role towards the survival of other commercially vital fishes.     

Discovery of quinolinediones exhibiting a heat shock response and angiogenesis inhibition

A series of substituted quinoline-5,8-diones were synthesized and evaluated as inhibitors of the chaperone protein Hsp90 using two assays: competition for binding to C-terminal ATP-binding site and competition for binding to N-terminal ATP-binding site. In addition, the ability of the compounds to induce the heat shock response was determined using a reporter fibroblast cell line. Of all the compounds assayed, only 6-aziridinyl-2-biphenylquinoline-5,8-dione induced a heat shock response and did so without interacting at the ATP binding sites of Hsp90. COMPARE analysis was carried out on quinoline-5,8-diones active in the National Cancer Institute's 60-cell line screen with the goal of discovering quinoline-5,8-dione structures that interact with other cellular targets (molecular targets) important for cancer chemotherapy. COMPARE analysis led to the discovery of a combretastatin-like quinoline-5,8-dione structure that, in fact, inhibited angiogenesis.     

Heat shock paradox and a new role of heat shock proteins and their receptors as anti-inflammation targets

This article discusses the role of heat shock proteins (Hsps) and their receptors as anti-inflammation targets. Hsps are highly conserved proteins that protect cells against noxious or deleterious stimulus. Intracellular Hsps function as molecular chaperones governing protein assembly, folding, or transport and as anti-apoptotic regulators of cell signalling pathways leading to cell death. In addition, intracellular Hsps have recently been shown to have an anti-inflammatory role in various inflammatory conditions such as infection, ischemia/reperfusion injury, and cardiovascular diseases. However, the heat shock response and the induction of Hsps have paradoxical effects against cell injury. Hsp induction before a pro-inflammatory stimulus is clearly beneficial but Hsp induction after a pro-inflammatory stimulus is cytotoxic. These paradoxical and contradictory effects may result from the different functions of intracellular versus extracellular Hsps. Extracellular Hsps released from cells with compromised integrity may function as danger signals activating innate immunity by interacting with their receptors. Therefore, modulating the levels of intracellular Hsps or the activities of Hsp receptors will be potential drug targets in inflammation.     

The induction of heat shock proteins as a potential strategy to treat neurodegenerative disorders

Neurodegenerative diseases, whether acute or chronic, are a tremendous medical problem in the modern world. Therapies are rare and only applied after a vast amount of neurons are lost. Many efforts have been made to develop new strategies to treat these disorders, but so far, there has been no breakthrough. A characteristic shared by some experimental neuroprotective substances is the induction of the heat shock response, in particular the expression of the heat shock proteins Hsp70 and Hsp27. These Hsps protect cells from cell death induced by various noxious stimuli and inhibit various cellular death pathways. Gene therapy, transgenic mice and drugs inducing Hsps in the brain decrease the infarction area after ischemia and protect neurons and nonneuronal cells of the brain. Furthermore, recent data hint toward a protective role of Hsps in chronic neurological diseases. The induction of Hsps as a possible treatment for stroke, Alzheimer's disease and Huntington's disease is discussed.     

Neurodegenerative conformational disease and heat shock proteins

Many major neurodegenerative diseases are associated with proteins misfolding and aggregation, which are also called "neurodegenerative conformational disease". The interaction of gene mutation and environmental factors are probably primary events resulting in oligomer and aggregate formations of proteins. Moreover, the dysfunctions of protein control systems, i.e. the ubiquitin-proteasome system and autophagy-lysosomal system, also contribute to the neurodegenerative process. The present review mainly summarizes protein misfolding and aggregation in the development of neurodegenerative conformational disease and the underling mechanisms, as well as upregulation of heatshock proteins as a promising treatment method for this kind of disease.     

The water,DNA, collagen and noncollagen protein contents in embryos after maternal administration of a teratogenic dose of phenytoin

The growth of developing A/J mouse embryos was studied after maternal administration of phenytoin (Dilantin®), an anticonvulsant drug. Wet weight, dry weight, protein and DNA contents of the embryos were quantitated 24 h after drug administration. Collagen content was investigated because of its importance in cellular differentiation. The wet and dry weights of embryos from phenytoin-treated mothers were 52.3 and 57.5%, respectively, of that of embryos of control mothers. DNA and protein contents were also decreased in embryos from phenytoin-treated mothers. Collagen represented only 0.07% of the protein present in day 11 control embryos, but was increased 4.9-fold in embryos from phenytoin-treated mothers in comparison to controls. These results suggest that phenytoin reduces overall embryonic growth but stimulates collagen synthesis.     

Altered behavioral responses to intense foot shock in socially-isolated rats

Male Wistar rats were isolated immediately after weaning for 12 weeks and exposed to electric foot shock of various intensities. The shock-elicited jumping behavior was measured every ten minutes for one hr. The frequency of jumping in isolated rats was lower than that in grouped and the difference between two groups was the greatest with the most intense shock. In these experimental situations, there was no significant difference in monoamine turnover rate between the two groups while noradrenaline turnover markedly increased in both groups. Chlorpromazine suppressed the jumping in a dose-dependent manner in both groups with stronger suppression in isolated rats. Methamphetamine facilitated the jumping in grouped rats dose-dependently while the drug rather depressed it in the isolated. From these results and the behavioral similarity between the isolated and 6-hydroxydopamine treated rats under foot shock situation, it was suggested that the receptor supersensitivity of central catecholaminergic neurons was involved in the behavioral change in isolated rats.     

Radiation-induced stress proteins - the role of heat shock proteins (HSP) in anti- tumor responses

Together with surgery and chemotherapy, ionizing irradiation is one of the key therapeutic approaches to treat cancer. More than 50 percent of all cancer patients will receive radiotherapeutic intervention at some stage of their disease. The more precise instrumentation for delivery of radiotherapy and the emphasis on hypofractionation technologies have drastically improved loco-regional tumor control within the last decades. However, the appearance of distant metastases often requires additional systemic treatment modalities such as chemotherapy. High dose chemotherapy is generally considered as immunosuppressive and can cause severe adverse effects. Therefore, we want to elucidate the effects of ionizing irradiation on the immune system and provide immunological treatment strategies which are induced by the host's stress response. Similar to other stressors, ionizing irradiation is known to enhance the synthesis of a variety of immune-stimulatory and -modulating molecules such as heat shock proteins (HSP), high mobility group box 1 (HMGB1) and survivin. Herein, we focus on HSP that exhibit an unusual cell membrane localization and release mechanism in tumor cells. These tumor-specific characteristics render HSP as ideal targets for therapeutic interventions. Depending on their intra/membrane and extracellular localization HSP have the ability to protect tumor cells from stress-induced lethal damage by interfering with antiapoptotic pathways or to elicit anti-cancer immunity.     

Embryonic exposure to lead: comparison of immune and cellular responses in unchallenged and virally stressed chickens

Lead, a ubiquitous environmental contaminant, has been shown to modulate various functions of the immune system and decrease host resistance to infectious disease. However, limited information is available concerning the direct effects of lead on the host immune response to an infectious agent after developmental exposure. The current study utilized chickens to examine the effect of embryonic lead exposure on immune and cellular responses during viral challenge. Sublethal doses of lead were introduced into fertilized Cornell K Strain White Leghorn chicken eggs via the air sac at day 5 or day 12 of embryonic development (designated as E5 and E12, respectively). Four-week-old female chickens were inoculated with infectious bronchitis virus (IBV) strain M41. Antibody titer to IBV, delayed-type hypersensitivity (DTH) response against bovine serum albumin (BSA), the absolute number and percentage of leukocyte subpopulations, and interferon-gamma (IFN-gamma)-like cytokine production by splenocytes were evaluated at 5-6 weeks of age. While antibody response to IBV in juvenile chicks was unaffected by the in ovo lead exposure, IFN-gamma-like cytokine production by splenocytes was significantly depressed following lead exposure at both developmental stages. In contrast with this pattern, the DTH response against BSA was unaffected following E5 exposure, but was significantly decreased after E12 exposure to lead. These changes were similar to those previously reported in chickens not exposed to IBV. While lead exposure at E5 induced significant changes in the percentage of circulating heterophils at 1 day postinfection (dpi), lead did not cause any change in relative leukocyte counts after E12 exposure. At 7 dpi, E5 lead exposure resulted in decreased absolute number and percentage of circulating lymphocytes, while total leukocyte counts, and the absolute number and percentage of circulating monocytes and heterophils were significantly reduced in E12 lead-exposed chickens. These results suggest that low-level exposure to lead has a direct effect on the developing chicken immune system, which is evident even during a postnatal infection. Furthermore, some of the changes were observed only when chicks were stressed by the viral infection. It appears that lead exposure during different stages of embryonic development is likely to result in different immunotoxic outcomes in juveniles.     

Renal heat shock proteins over-expression due to anabolic androgenic steroids abuse

Chronic use of anabolic adrogenic steroids (AAS) has been known to cause serious adverse effects. While the effects of AASs on cardiovascular system are well known, toxicity on other organs has received less attention. A doserelated nephrotoxic effect has been proposed and a wide variety of morpho-functional damages have been observed, but the exact pathophysiological mechanism of action is still not well known. In the present minireview, we highlight the remaining issues through an analysis of the pertinent literature. As with HSPs toxic agents their overexpression could be considered a protective reaction against AAS abuse however, comprehensive studies concerning the whole range of Hsps/chaperones expressions in all organs after long term use of AAS are needed.