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Male reproduction is one of the primary health endpoints identified in rodent studies for some phthalates, such as DEHP (Bis(2-ethylhexyl) phthalate), DBP (Dibutyl phthalate), and BBP (Benzyl butyl phthalate). The reduction in testosterone level was used as an intermediate key event for grouping some phthalates and to establish a reference point for risk assessment. Phthalates, and specifically DEHP, are one of the chemicals for which the greatest number of non-monotonic dose responses (NMDRs) are observed. These NMDRs cover different endpoints and situations, often including testosterone levels. The presence of NMDR has been the subject of some debate within the area of chemical risk assessment, which is traditionally anchored around driving health-based guidance values for apical endpoints that typically follow a clear monotonic dose-response. The consequence of NMDR for chemical risk assessment has recently received considerable attention amongst regulatory agencies, which confirmed its relevance particularly for receptor-mediated effects. The present review explores the relationship between DEHP exposure and testosterone levels, investigating the biological plausibility of the observed NMDRs. The Adverse Outcome Pathway (AOP) concept is applied to integrate NMDRs into Key Event Relationships (KERs) for exploring a mechanistic understanding of initial key events and possibly associated reproductive and non-reproductive adverse outcomes., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Complications of the intrathecal route may cause potential toxicity related to the medical device and properties of the administered drug and/or excipient. A description of clinical and histological effects of polyethylene glycol and miripirium after Depo-Medrol injection, and the adverse reactions of particulate methylprednisolone acetate was conducted. The safety of the intrathecal route with excipients, label and off-label drugs is discussed., Methods: A bibliographic search in Medline, Google, and Cochrane database from 1940 to June 2016 was performed. The keywords included 'intrathecal methylprednisolone acetate', 'miripirium', 'myristyl-gamma-picolinium', 'side effects', 'intrathecal Depo-Medrol', 'polyethylene glycol', and 'intrathecal devices' used individually or in combination., Results: Adverse reactions have been reported with this intrathecal administration route such as arachnoiditis, bladder dysfunction, headache, meningitis. Some pharmaceutical excipients have been associated with specific toxicity issues and with allergic and anaphylaxis reactions. Additives of methylprednisolone acetate formulations such as polyethylene glycol and miripirium chloride can be neurotoxic when injected intrathecally. Polyethylene glycol-an antimicrobial agent widely used in pharmaceutical drugs-has been associated with cardiovascular, hepatic, respiratory, and CNS toxicity., Conclusions: Intrathecal methylprednisolone acetate (Depo-Medrol) therapy seems not fully safe due to reported adverse events. The use of other forms of corticosteroid therapy free from excipients should be emphasized such as soluble methylprednisolone sodium succinate.

Rationale: Transport across the BBB is a determinant of the rate and extent of drug distribution in the brain. Heroin exerts its effects through its principal metabolites 6-monoacetyl-morphine (6-MAM) and morphine. Morphine is a known substrate of P-glycoprotein (P-gp) at the blood-brain-barrier (BBB) however, little is known about the interaction of heroin and 6-MAM with P-gp., Objective: The objective of this paper is to study the role of the P-gp-mediated efflux at the BBB in the behavioral and molecular effects of heroin and morphine., Methods: The transport rates of heroin and its main metabolites, at the BBB, were measured in mice by in situ brain perfusion. We then examined the effect of inhibition of P-gp on the acute nociception, locomotor activity, and gene expression modulations induced by heroin and morphine. The effect of P-gp inhibition during the acquisition of morphine-induced place preference was also studied., Results: Inhibition of P-gp significantly increased the uptake of morphine but not that of heroin nor 6-MAM. Inhibition of P-gp significantly increased morphine-induced acute analgesia and locomotor activity but did not affect the behavioral effects of heroin; in addition, acute transcriptional responses to morphine were selectively modulated in the nucleus accumbens. Increasing morphine uptake by the brain significantly increased its reinforcing properties in the place preference paradigm., Conclusions: The present study demonstrated that acute inhibition of P-gp not only modulates morphine-induced behavioral effects but also its transcriptional effects and reinforcing properties. This suggests that, in the case of morphine, transport across the BBB is critical for the development of dependence.

The mycotoxin ochratoxin A (OTA) is a rodent carcinogen produced by species of the ubiquitous fungal genera Aspergillus and Penicillium. OTA is found in a variety of food items and as a consequence is also found in human plasma (average concentrations found in this study: 0.1-1 ng OTA/ml plasma). To improve the scientific basis for cancer risk assessment the toxicokinetic profile of OTA was studied in one human volunteer following ingestion of 395 ng 3H-labeled OTA (3.8 microCi). A two-compartment open model consisting of a central compartment was found to best describe the in vivo data. This two-compartment model consisted of a fast elimination and distribution phase (T1/2 about 20 h) followed by a slow elimination phase (renal clearance about 0.11 ml/min.) and a calculated plasma half-life of 35.55 days. This half-life was approximately eight times longer than that determined previously in rats. In addition, the intraindividual fluctuation of OTA plasma levels was investigated in eight individuals over a period of 2 months. The concentrations determined ranged between 0.2 and 0.9 ng OTA/ml plasma. The plasma levels in some individuals remained nearly constant over time, while others varied considerably (e.g. increase of 0.4 ng/ml within 3 days, decrease of 0.3 ng/ml within 5 days) during the observation period. This intraindividual fluctuation in OTA plasma levels, which may represent differences in OTA exposure and/or metabolism, as well as the large difference in plasma half-life in humans compared to rats must be taken into consideration when the results of rat cancer study data are extrapolated to humans for risk assessment purposes.

A method for 24 h recording of the heart rate (HR) in unrestrained, freely moving rats is described. Commercially available biotelemetry transmitters were used in combination with normal ranged FM-receivers. The data presented show a pronounced diurnal rhythm in the HR of the rat. When the rats are exposed to noise a large increase in the HR could be demonstrated. The system described is also suitable for analysis of the time parameters of the electro-cardiogram (ECG).