Enhancement of porcine circovirus 2 replication in porcine cell lines by IFN-gamma before and after treatment and by IFN-alpha after treatment.

Stimulation of the porcine immune system causes increased replication of porcine circovirus 2 (PCV2) in vivo. In the present study, we investigated whether various cytokines (interleukin-1 [IL-1], IL-6, IL-10, tumor necrosis factor-alpha [TNF-alpha], interferon-alpha [IFN-alpha], and IFN-gamma) are able to influence PCV2 infection in vitro. No changes were observed in IL-1, IL-6, TNF-alpha, or IL-10-treated cells. However, it was demonstrated that IFN- alpha and IFN-gamma influenced PCV2 infection in porcine kidney cells (PK-15) and porcine monocytic cells (3D4/31). IFN-gamma added to the culture medium before, during, or after inoculation increased the number of PCV2 antigen- positive cells, respectively, by 418%, 171%, and 691% in PK-15 cells and by 706%, 114%, and 423% in 3D4/31 cells. IFN-alpha pretreatment decreased the number of infected PK-15 cells. When it was added after inoculation, IFN-alpha enhanced PCV2 infection by 529% in PK-15 cells and by 308% in 3D4/31 cells. The effect of both IFNs on PCV2 infection was dose dependent and could be blocked with IFN-alpha or IFN-gamma neutralizing antibodies. Leukocyte-derived porcine IFN-gamma induced a similar effect on PCV2 infection. Treatment of PK- 15 cultures with IFN-gamma caused a 20 times higher production of progeny virus. Confocal microscopy studies showed that the enhancing effect of IFN-gamma on PCV2 infection was achieved by increased internalization of PCV2 virionlike particles (VLPs). Binding of the VLPs to the cell or expression kinetics of PCV2 proteins in infected cells were not altered by IFN-gamma treatment. To our knowledge, this study reports the first enhancement of a viral infection by treatment with type I or type II IFNs.     

Anxiolytics,sedatives and hypnotics

Anxiolytics and sedatives are used in current anaesthetic practice for two main reasons: for anxiolysis before surgery and as adjuvants during anaesthesia. A wide choice of agents are available. Their safety profile is dependent on their pharmacokinetic and pharmacodynamic profiles, patient co-morbidity and the experience of the clinician using them. All sedative drugs have the potential to cause severe respiratory depression, and hence they should only be used with standard physiological cardiorespiratory monitoring. This is especially true of procedural sedation administered by non-anaesthetists in remote locations. Drugs used for anaesthesia vary in their pharmacology, but have broadly similar clinical effects. The choice of drug is usually a matter of individual preference, although pharmacokinetic and pharmacodynamic parameters do influence the selection of anaesthetic agents, especially in day case surgery. Most intravenous agents are thought to alter consciousness by an effect at the GABA_A or N-methyl-d-aspartate receptors or both. Our understanding of the mechanisms of action of anaesthetic drugs is incomplete, not least because of a lack of understanding of consciousness. Several theories have been proposed over the last century, but none of them have managed to comprehensively elucidate the processes involved. There is now a sense of expectation that with the use of modern imaging techniques, anaesthetic drug action can be better understood, and that this may help in our understanding of consciousness and cognitive functions.     

Developmental Exposure to 4-hydroxy-2,3,3',4',5-pentachlorobiphenyl (4-OH-CB107): Long-Term Effects on Brain Development, Behavior, and Brain Stem Auditory Evoked Potentials in Rats

In the present study the developmental neurotoxic effects ofthe PCB metabolite 4-OH-2,3,3',4',5-pentachlorobiphenyl (4-OH-CB107)were compared with effects caused by a mixture of parent polychlorinatedbiphenyl (PCB) congeners (Aroclor 1254). Pregnant female Wistarrats were exposed to 0.5 or 5 mg 4-OH-CB107, or 25 mg Aroclor1254 per kg body weight from gestation days 10 to 16. Plasmathyroid hormone levels were significantly decreased in the offspringof all treatment groups at postnatal day 4 (PND 4). Behavioralexperiments using an open field paradigm revealed an impairedhabituation in male offspring of all treatment groups at PND130. Passive avoidance experiments indicated significant influenceson the time course of step-down latencies across trials in exposedmale rats. Catalepsy induced by haloperidol showed increasesin latencies to movement onset in female offspring exposed to0.5 mg 4-OH-CB107 compared to Aroclor 1254 treated offspringat PND 168–175. Male offspring exposed to 4-OH-CB107 orAroclor 1254 showed decreases in latencies compared to controlanimals. Brain stem auditory evoked potentials (BAEPs) measuredat PND 300–310 showed significant increases in auditorythresholds in the low frequency range between Aroclor 1254 and4-OH-CB107 (5 mg/kg bw) treated animals. Measurements of neurotransmitterlevels revealed effects of Aroclor 154 exposure on both thedopaminergic and the serotonergic systems, whereas 4-OH-CB107exposure affected dopaminergic and noradrenergic systems, withslight but not significant effects on the serotonergic system.These results indicate that 4-OH-CB107 is able to induce long-termeffects on behavior and neurodevelopment. The observed effectsfor 4-OH-CB107 are similar to, but in some aspects differentfrom, the effects observed after Aroclor 1254 exposure.     

Zaprinast, a phosphodiesterase type-5 inhibitor, alters paced mating behavior in female rats

Nitric oxide (NO) is the primary mediator of blood flow in female genital tissues and drugs that enhance the activity of nitric oxide, such as phosphodiesterase type-5 (PDE-5) inhibitors, increase vaginal blood flow in anesthetized rats. The goal of the present study was to test the effects of one PDE-5 inhibitor, zaprinast, on the display of sexual behaviors in gonadectomized, estrogen- and progesterone-treated female rats. Experiment 1 demonstrates that zaprinast alters paced mating behavior by lengthening the contact-return latency to ejaculation; there is a significant relationship between dose of zaprinast (range 1.5-6 mg/kg) and contact-return latency to ejaculation. Experiment 2 illustrates that zaprinast has no effect on preference for an intact male as measured in a No Contact partner preference test. Rats receiving zaprinast tend to exhibit reduced locomotor activity in both experiments. Collectively, these findings demonstrate that modulation of the NO-cGMP pathway using a PDE-5 inhibitor alters the display of paced mating behaviors in rats.     

An intact medial preoptic area is necessary for zaprinast to modulate paced mating behavior in female rats

The present study examined the interaction between the regulation of paced mating behavior by the medial preoptic area (mPOA) and by the nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway, as modulated by zaprinast, a phosphodiesterase inhibitor. Rats receiving mPOA or sham lesions were tested for paced mating behavior. Subsequently, rats were treated with zaprinast (3 mg/kg) before a second paced mating test. The expected lengthening of contact-return latencies following intromissions and ejaculations was observed in rats with mPOA lesions relative to rats with sham lesions. In addition, rats with sham lesions responded to zaprinast with a lengthening of contact-return latency following ejaculation. Contact-return latencies did not change in response to zaprinast in rats with mPOA lesions. These results demonstrate that the alterations in paced mating behavior observed in rats with mPOA lesions persist despite manipulation of the nitric oxide-cyclic guanosine monophospate pathway.     

Sex- and age-specific effects of anabolic androgenic steroids on reproductive behaviors and on GABAergic transmission in neuroendocrine control regions

Illicit use of anabolic androgenic steroids (AAS) has become a prevalent health concern not only among male professional athletes, but, disturbingly, among a growing number of women and adolescent girls. Despite the increasing use of AAS among women and adolescents, few studies have focused on the effects of these steroids in females, and female adolescent subjects are particularly underrepresented. Among the hallmarks of AAS abuse are changes in reproductive behaviors. Here, we discuss work from our laboratories on the actions of AAS on the onset of puberty and sexual behaviors in female rodents, AAS interactions and sex- and age-specific effects of these steroids on neural transmission mediated by gamma-aminobutyric acid receptors within forebrain neuroendocrine control regions that may underlie AAS-induced changes in these behaviors.     

Development of Issoria lathonia (Lepidoptera: Nymphalidae) on zinc-accumulating and nonaccumulating Viola species (Violaceae)

The larvae of Issoria lathonia L. feed in natural conditions on several Viola spp., among which are the zinc-accumulating Viola calaminaria (Gingins) Lej. and the nonmetal-accumulating Viola tricolor L. To examine how I. lathonia caterpillars cope with the naturally high foliar zinc concentration of V. calaminaria, we compared the growth of caterpillars reared on leaves varying in zinc concentration. Larvae were fed in controlled conditions with V. calaminaria and V. tricolor grown on noncontaminated soil (i.e., two low-Zn diets) and with V. calaminaria grown on zinc-enriched soil (i.e., one high-Zn diet). Larvae had a higher growth rate when fed with noncontaminated V. calaminaria compared to zinc-enriched V. calaminaria, suggesting that zinc slows down larval growth. However, larvae consumed more leaves of zinc-enriched V. calaminaria (+45%; estimated from fecal mass) compared with noncontaminated V. calaminaria, suggesting that zinc accumulation would not be advantageous to plants. Caterpillars reared on high-zinc leaves regulate their internal zinc concentration through excretion of highly metal-concentrated feces. When kinetics of growth on both low-zinc diets were compared, it appeared that larval development was faster on noncontaminated V. calaminaria than on V. tricolor. This suggests that more nutrients or less feeding inhibitors in V. calaminaria account for fastest growth. Developmental rates on V. tricolor and on zinc-enriched V. calaminaria were similar, despite the high leaf zinc concentration of the latter species. Together with the abundance of V. calaminaria on calamine soils, this may explain why the largest populations of I. lathonia develop on V. calaminaria in Belgium.     

T-Screen as a tool to identify thyroid hormone receptor active compounds

The T-Screen represents an in vitro bioassay based on thyroid hormone dependent cell proliferation of a rat pituitary tumour cell line (GH3) in serum-free medium. It can be used to study interference of compounds with thyroid hormone at the cellular level, thus bridging the gap between limitations of assays using either isolated molecules (enzymes, transport proteins) or complex in vivo experiments with all the complex feedback mechanisms present. Compounds are tested both in the absence and presence of thyroid hormone (EC(50) concentration of T(3)) to test for both agonistic and antagonistic potency. Thyroid hormones (3,3'-5-triiodothyronine: T(3) and 3,3',5,5'-tetraiodothyroxine: T(4)) and compounds resembling the structure of thyroid hormones (3,3'-5-triiodothyroacetic acid: Triac; 3,3',5,5'-tetraiodothyroacetic acid: Tetrac) induced cell growth, with the rank order Triac > T(3) > Tetrac > T(4) (relative potency = 1.35 > 1 > 0.29 > 0.07), which is identical to published affinities of these compounds for nuclear thyroid hormone receptors. Exposure to 5,5'-diphenylhydantoin (DPH) in the presence of 0.25nM T(3) resulted in up to 60% decreased cell growth at 200μM DPH. No effect of DPH on basal metabolic activity of GH3 cells was observed at this concentration. Fentinchloride (IC(50) = 21nM) decreased cell growth induced by 0.25nM T(3), whereas parallel exposure to these concentrations in the absence of T(3) did not alter basal metabolic activities of GH3 cells. Apolar sediment extracts from the Dommel (34%) and Terneuzen (14%) decreased cell growth in the presence of 0.25nM T(3), whereas the extract from Hoogeveen increased cell growth (26%) and the extract from North Sea Channel had no effect. The T-Screen proved to be a fast and functional assay for assessing thyroid hormone receptor active potencies of pure chemicals or environmental mixtures.     

Effects of in utero exposure to 4-hydroxy-2,3,3',4',5-pentachlorobiphenyl (4-OH-CB107) on developmental landmarks, steroid hormone levels, and female estrous cyclicity in rats.

Previous studies have revealed that one of the major metabolites of PCBs detected in human blood, 4-OH-2,3,3',4',5-pentaCB (4-OH-CB107), accumulated in fetal liver, brain, and plasma and reduced maternal and fetal thyroid hormone levels after prenatal exposure to pregnant rats from gestational days (GD) 10-16. In the present study, the effects of 4-OH-CB-107 on developmental landmarks, steroid hormone levels, and estrous cyclicity of rat offspring after in utero exposure to 4-OH-CB107 was investigated. Pregnant rats were exposed to 0, 0.5, and 5.0 mg 4-OH-CB107 per kg bw from GD 10 to GD 16. Another group of rats was exposed to Aroclor 1254 (25 mg/kg bw) to study the differences between effects caused by parent PCB congeners and the 4-OH-CB107 alone. A significant, dose-dependent prolongation of the estrous cycle was observed in 75% and 82% of female offspring exposed to 0.5 and 5.0 mg 4-OH-PCB107, respectively, compared to 64% of Aroclor 1254 (25 mg/kg) exposed offspring. The diestrous stage of the estrous cycle was prolonged, resembling a state of pseudopregnancy, which might reflect early signs of reproductive senescence. Plasma estradiol concentrations in female rat offspring were significantly increased (50%) in the proestrous stage after exposure to 5 mg 4-OH-CB107 per kg bw. No effects on estradiol levels were observed in Aroclor 1254 treated animals. These results indicate that in utero exposure to 4-OH-CB107 leads to endocrine-disrupting effects, especially in female offspring. The possible impact on neurobehavior following exposure to 4-OH-CB107 will be reported elsewhere.