Teratogenic potential of two neurotropic drugs, haloperidol and dextromoramide, tested on mouse embryos

High-throughput screening for analysis of in vitro toxicity

The influence of combinatorial chemistry and high-throughput screening (HTS) technologies in the pharmaceutical industry during the last 10 years has been enormous. However, the attrition rate of drugs in the clinic due to toxicity during this period still remained 40-50%. The need for reduced toxicity failure led to the development of early toxicity screening assays. This chapter describes the state of the art for assays in the area of genotoxicity, cytotoxicity, carcinogenicity, induction of specific enzymes from phase I and II metabolism, competition assays for enzymes of phase I and II metabolism, embryotoxicity as well as endocrine disruption and reprotoxicity. With respect to genotoxicity, the full Ames, Ames II, Vitotox, GreenScreen GC, RadarScreen, and non-genotoxic carcinogenicity assays are discussed. For cytotoxicity, cellular proliferation, calcein uptake, oxygen consumption, mitochondrial activity, radical formation, glutathione depletion as well as apoptosis are described. For high-content screening (HCS), the possibilities for analysis of cytotoxicity, micronuclei, centrosome formation and phospholipidosis are examined. For embryotoxicity, endocrine disruption and reprotoxicity alternative assays are reviewed for fast track analysis by means of nuclear receptors and membrane receptors. Moreover, solutions for analyzing enzyme induction by activation of nuclear receptors, like AhR, CAR, PXR, PPAR, FXR, LXR, TR and RAR are given.

Effect of prenatal haloperidol exposure on behavioral alterations in rats

Pregnant Charles-Foster rats were exposed to haloperidol (HAL), a neuroleptic drug that binds to and blocks dopamine (DA) receptor subtypes at a dose of 2.5 mg/kg body weight (intraperitoneally) from Gestation Day (GD) 12 to 20. The animals from both treated as well as vehicle control groups were allowed to deliver on GD 21. The offspring culled at birth on the basis of sex and weight were subjected to behavioral tests at the age of 8 weeks. The HAL-treated rat offspring showed a significant increase in anxiogenic behavior on the open field, elevated plus-maze and elevated zero-maze tests when compared with the vehicle-treated (control) rat offspring of the same age group. These findings suggest that prenatal exposure to HAL during a critical period of brain development leaves a lasting imprint on the brain, resulting in abnormal anxiety states, possibly through dopaminergic neurotransmission mechanisms.

A study on the teratogenic and cytotoxic effects of safflower extract

In recent years, the use of carthami flos (the flowers of Carthamus tinctorius L.) as a coloring and flavoring agent has increased as a food additive in Iran. In order to evaluate its safety, the teratogenic effects of carthami flos on the central nervous system development in mice was investigated. Furthermore, its cytotoxic effect on the rat nervous cell culture was studied to complete safety evaluations. For teratogenic studies, after natural mating, pregnant mice were divided into test and control groups. The groups were treated with different dosage regimens of aqueous carthami flos extract during 0-8 days of gestation. Embryos were then isolated at the 13th gestation day and evaluated for macroscopic, microscopic and morphometric characteristics. The results showed that in higher doses (1.6 and 2 mg/kg/day) the embryos were absorbed, whereas with lower dose (1.2 mg/kg/day) changes in external, internal and longitudinal diameters, open neuropore, changes in cellular orientation and cellular degeneration were observed. The results obtained from cytotoxic assay also demonstrated a concentration-dependent cytotoxic effect of carthami flos extract. It is concluded that the use of carthami flos as a food additive should be reconsidered.

Embryotoxicity of 25 psychotropic drugs: a study using CHEST

Twenty five psychotropic drugs were ranked according to the embryotoxicity dose ranges estimated by the Chick Embryotoxicity Screening Test (CHEST). The chick results were compared with some data for common laboratory mammals. In 17 psychotropic drugs a deleterious dose-dependent effect upon the embryonic cardiovascular system was disclosed, terminating in immediate cardiac arrest.

The absence of teratogenic effects of some analgesics used in anaesthesia

The possibility exists that agents used in anaesthesia may have adverse teratogenic effects on staff, patients, and developing fetuses. It has been shown that a range of neurotropic drugs, when injected into pregnant mice on the 9th day of gestation, produce a characteristic group of central nervous system malformations in their fetuses. We have studied the possible teratogenicity of pethidine, fentanyl, phenoperidine and lignocaine when tested in this way and conclude that they appear to have less effect than other neurotropic drugs previously tested.