Glutathione S-Transferase P Influences Redox Homeostasis and Response to Drugs that Induce the Unfolded Protein Response in Zebrafish.

We have created a novel glutathione S-transferase π1 (gstp1) knockout (KO) zebrafish model and used it for comparative analyses of redox homeostasis and response to drugs that cause endoplasmic reticulum (ER) stress and induce the unfolded protein response (UPR). Under basal conditions, gstp1 KO larvae had higher expression of antioxidant nuclear factor erythroid 2-related factor 2 (Nrf2) accompanied by a more reduced larval environment and a status consistent with reductive stress. Compared with wild type, various UPR markers were decreased in KO larvae, but treatment with drugs that induce ER stress caused greater toxicities and increased expression of Nrf2 and UPR markers in KO. Tunicamycin and 02-{2,4-dinitro-5-[4-(N-methylamino)benzoyloxy]phenyl}1-(N,N-dimethylamino)diazen-1-ium-1,2-diolate (PABA/nitric oxide) activated inositol-requiring protein-1/X-box binding protein 1 pathways, whereas thapsigargin caused greater activation of protein kinase-like ER kinase/activating transcription factor 4/CHOP pathways. These results suggest that this teleost model is useful for predicting how GSTP regulates organismal management of oxidative/reductive stress and is a determinant of response to drug-induced ER stress and the UPR. SIGNIFICANCE STATEMENT: A new zebrafish model has been created to study the importance of glutathione S-transferase π1 in development, redox homeostasis, and response to drugs that enact cytotoxicity through endoplasmic reticulum stress and induction of the unfolded protein response.

Effect of elicitors on holm oak somatic embryo development and efficacy inducing tolerance to Phytophthora cinnamomi.

Holm oak trees (Quercus ilex L.) mortality is increasing worryingly in the Mediterranean area in the last years. To a large degree this mortality is caused by the oomycete Phytophthora spp., which is responsible for forest decline and dieback in evergreen oak forest areas of the southwestern Iberian Peninsula. This study is based on the possibility of applying chemical elicitors or filtered oomycete extracts to holm oak somatic embryos (SE) in order to induce epigenetic memory, priming, that may increase tolerance to the pathogen in future infections. To this end, we first examined the effect of priming treatments on SE development and its oxidative stress state, to avoid elicitors that may cause damage to embryogenic tissues. Both, the sterile oomycete extracts and the chemical elicitor methyl jasmonate (MeJA) did not produce any detrimental effect on SE growth and development, unlike the elicitors benzothiadiazole (BTH) and p-aminobenzoic acid (PABA) that reduced the relative weight gain and resulted in necrotic and deformed SE when were applied at high concentrations (25 µM BTH or 50 µM PABA) in accordance with their high malondialdehyde content. No significant differences among elicitation treatments were found in dual culture bioassays, although those SEs elicited with 50 µM MeJA increased H2O2 production after challenged against active oomycete indicating the activation of stress response. Since this elicitation treatment did not produce any adverse effect in the embryogenic process we suggest that could be used in further priming experiments to produce holm oak plants adapted to biotic stress.

Evaluation of the Oxidative Stress Status in Zebrafish (Danio rerio) Liver Induced by Three Typical Organic UV Filters (BP-4, PABA and PBSA).

Organic UV filters are a kind of emerging pollutants, which have been widely used in personal care products (PCPs). This study evaluated the effects of benzophenone-4 (BP-4), 4-aminobenzoic acid (PABA), and 2-phenylbenzimidazole-5-sulfonic acid (PBSA) on the selected indices of antioxidative responses in zebrafish (Danio rerio) liver. Zebrafish were exposed to two different doses (i.e., 0.5 and 5 mg L-1) of semi-static water with three individual compounds. Liver samples were collected on 7 and 14 days to analyze biochemical indicators, including superoxide dismutase (SOD), glutathione S-transferase (GST), reduced glutathione (GSH), and malondialdehyde (MDA). Oxidative stress occurred in zebrafish liver with significantly changed indicators during the whole exposure period. Different experimental groups could induce or inhibit the activity of antioxidant enzymes with varying degrees. With a prolonged exposure time and increased exposure dose, the hepatic lipid peroxidation was also obviously observed. Moreover, the toxicity order of three organic UV filters was analyzed using the integrated biomarker response (IBR) index and the results indicate that exposure to PABA for 7 days at 0.5 mg L-1 and PBSA for 7 days at 5 mg L-1 induced the most severe oxidative stress in the liver of zebrafish.

Utilization of the ex vivo LLNA: BrdU-ELISA to distinguish the sensitizers from irritants in respect of 3 end points-lymphocyte proliferation, ear swelling, and cytokine profiles.

Dermal exposure to chemicals may result in allergic or irritant contact dermatitis. In this study, we performed ex vivo local lymph node assay: bromodeoxyuridine-enzyme-linked immunosorbent assay (LLNA: BrdU-ELISA) to compare the differences between irritation and sensitization potency of some chemicals in terms of the 3 end points: lymphocyte proliferation, cytokine profiles (interleukin 2 [IL-2], interferon-γ (IFN-γ), IL-4, IL-5, IL-1, and tumor necrosis factor α [TNF-α]), and ear swelling. Different concentrations of the following well-known sensitizers and irritant chemicals were applied to mice: dinitrochlorobenzene, eugenol, isoeugenol, sodium lauryl sulfate (SLS), and croton oil. According to the lymph node results; the auricular lymph node weights and lymph node cell counts increased after application of both sensitizers and irritants in high concentrations. On the other hand, according to lymph node cell proliferation results, there was a 3-fold increase in proliferation of lymph node cells (stimulation index) for sensitizer chemicals and SLS in the applied concentrations; however, there was not a 3-fold increase for croton oil and negative control. The SLS gave a false-positive response. Cytokine analysis demonstrated that 4 cytokines including IL-2, IFN-γ, IL-4, and IL-5 were released in lymph node cell cultures, with a clear dose trend for sensitizers whereas only TNF-α was released in response to irritants. Taken together, our results suggest that the ex vivo LLNA: BrdU-ELISA method can be useful for discriminating irritants and allergens.

Production of aromatics in Saccharomyces cerevisiae--a feasibility study.

Aromatics are amongst the most important bulk feedstocks for the chemical industry, however, no viable bioprocess exists today and production is still dependent on petro-chemistry. In this article the production of aromatic precursors such as p-hydroxybenzoic acid (PHBA) and p-amino benzoic acid (PABA) in Saccharomyces cerevisiae was evaluated using metabolic network analysis. Theoretical mass yields for PHBA and for PABA obtained by metabolic network analysis were 0.58 and 0.53 g g(glucose)⁻¹, respectively. A major setback for microbial production of aromatics is the high toxicity of the products. Therefore, PHBA and PABA toxicity was evaluated in S. cerevisiae. Minimal inhibitory concentrations of 38.3 g L⁻¹ for PHBA and 0.62 g L⁻¹ for PABA were observed. However, PABA toxicity could be alleviated in adaptation experiments. Finally, metabolic engineering was used to create proof of principle first generation strains of S. cerevisiae. Overall accumulation of 650 µM PHBA and 250 µM PABA could be achieved.

N-Acetylation of p-aminobenzoic acid and p-phenylenediamine in primary porcine urinary bladder epithelial cells and in the human urothelial cell line 5637.

N-Acetyltransferases (NAT) are important enzymes in the metabolism of certain carcinogenic arylamines, as N-acetylation decreases or prevents their bioactivation via N-hydroxylation. To study such processes in the bladder, cell culture models may be used, but metabolic competence needs to be characterized. This study focused on the N-acetylation capacity of two urothelial cell systems, using p-aminobenzoic acid (PABA) and the hair dye precursor p-phenylenediamine (PPD), two well-known substrates of the enzyme NAT1. The constitutive NAT1 activity was investigated using primary cultures of porcine urinary bladder epithelial cells (PUBEC) and in the human urothelial cell line 5637 to assess their suitability for further in vitro studies on PABA and PPD-induced toxicity. N-Acetylation of PABA and PPD was determined by high-performance liquid chromatography (HPLC) analysis in cytosols of the two cell systems upon incubation with various substrate levels for up to 60 min. The primary PUBEC revealed higher N-acetylation rates (2.5-fold for PABA, 5-fold for PPD) compared to the 5637 cell line, based on both PABA conversion to its acetylated metabolite and formation of mono- and diacetylated PPD. The urothelial cell systems may thus be useful as a tool for further studies on the N-acetylation of aromatic amines via NAT1.

Internalisation of hybrid titanium dioxide/para-amino benzoic acid nanoparticles in human dendritic cells did not induce toxicity and changes in their functions.

Nanoparticles (NPs) have been reported to penetrate into human skin through lesional skin or follicular structures. Therefore, their ability to interact with dendritic cell (DC) was investigated using DCs generated from monocytes (mono-DCs). Hybrid titanium dioxide/para-amino benzoic acid (TiO(2)/PABA) NPs did not induce any cell toxicity. NPs were internalised into DCs through macropinocytosis and not by a receptor-mediated mechanism. Confocal microscopy showed that NPs were not detected in the nucleus. These data are confirmed by electronic microscopy which demonstrated that hybrid NPs were rapidly in contact with cellular membrane and localised into cytoplasmic vesicles without colocalisation with clathrin-coated vesicles. Hybrid NPs did not induce CD86 or HLA-DR overexpression or cytokine secretion (IL-8 and TNF-α) indicating no DC activation. Internalisation of hybrid NPs did not modify DC response towards sensitisers such as nickel and thimerosal or LPS used as positive controls. Moreover, hybrid NPs did not induce any oxidative stress implicated in DC activation process. After mono-DC irradiation by ultraviolet A (UVA), hybrid NP-treated cells did not produce UVA-induced reactive oxygen species (ROS) and exhibited a better cell viability compared with UVA-irradiated control cells, suggesting a protecting effect of hybrid TiO(2)/PABA NPs against UVA-induced ROS.

Murine bone marrow-derived dendritic cells as a potential in vitro model for predictive identification of chemical sensitizers.

The identification of potential sensitizing chemicals is a key step in the safety assessment process. To this end, predictive tests that require no or few animals and that are reliable, inexpensive and easy to perform are needed. The aim of this study was to evaluate the performance of murine bone marrow-derived dendritic cells (BMDCs) in an in vitro skin sensitization model. BMDCs were exposed to six well-known allergens (dinitrochlorobenzene, DNCB; dinitrofluorobenzene, DNFB; Bandrowski's base, BB; paraphenylenediamine, PPD; nickel sulfate, NiSO(4); cinnamaldehyde, Cinn). Surface expression of MHC class II, CD40, CD54, and CD86 was measured by flow cytometry after 48h exposure to these chemicals. All the allergens tested induced a significant increase in marker expression, with an augmentation in the percentage of mature cells ranging from 2.3- to 10.5-fold change over control. The level of up-regulation was dependent on the concentration and the strength of the allergens. In contrast, the irritants (sodium dodecyl sulfate, SDS and 4-aminobenzoic acid, pABA) and the negative control (zinc sulfate, ZnSO(4)) tested induced either no modification or a down-regulation of membrane marker expression. Taken together, our data suggest that murine BMDCs may represent a new and valuable in vitro model to predict the sensitizing properties of chemicals.

Immobilization of simulated reducing agent at the surface of SiO2 fillers in dental composite resins.

To reduce the leachability of reducing agents from composite resins, immobilization of a simulated reducing agent at the surface of SiO2 fillers was examined. SiO2 plates were immersed in 2% 3-aminopropyltriethoxy silane/ethanol solution, and then immersed in dimethyl sulfoxide with 0.25 wt% 4-dimethyl amino benzoic acid (DMABA), 2.0 wt% 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride, and 0.5 wt% N-hydroxysuccinimide. Wide-scan spectrum of X-ray photoelectron spectroscopy did not detect carbon contamination. However, narrow scan detected an O=C-N peak at 399.8 eV, suggesting that DMABA could be immobilized on silane-coupled SiO2 plates. Further, surface plasmon resonance analysis indicated the adsorption of MMA at the surface of reducing agent-immobilized plate.

Structure-antileukemic activity relationship study of B- and D-ring modified and nonmodified steroidal esters of 4-methyl-3-N,N-bis(2-chloroethyl)amino benzoic acid: a comparative study.

This study was designed as a rational continuation of our research regarding the functional requirements essential for the antileukemic activity of compounds comprising an alkylating moiety and a modified steroid. The steroidal esteric derivatives of 4-methyl-3-N,N-bis(2-chloroethyl)amino benzoic acid were tested on leukemias P388 and L1210 in vivo and in normal human lymphocytes in vitro. Among them the B-lactamic steroidal esters proved more potent antileukemic agents than the 7-oxidized and those with a simple B-ring, but not more effective inducers of DNA damage and cell cycle arrest in vitro. We speculate that these results indicate a different mechanism of action induced by the lactamized B steroidal ring, in comparison to the 7-keto or the D-lactamic groups, which involves the interaction of the -NHCO- moiety with cellularcomponents essential for tumor growth. 4-Methyl-3-N,N-bis(2-chloroethyl)amino benzoic acid proved a more proper module for the B-lactams than chlorambucil and phenyl acetic acid's nitrogen mustard probably because the esteric bond is less cleaved by the esterases, resulting in an increased concentration of the drug in the vinicity of the target site essential for an antineoplasmatic response.

The coinitiator DMABEE induces death by apoptosis and necrosis in human monoblastoid cells.

4-N,N-Dimethyl amino benzoic acid ethylester (DMABEE), a leachable lipophilic component of polymer-based dental-filling materials, has been shown to interact with cell membrane phospholipids, such as phosphatidylcholine and phosphatidylserine (PS). One marker of cellular death by apoptosis is the change in architecture of the plasma membrane involving the translocation of the negatively charged PS from the inner to the outer leaflet of the cell membrane. We therefore hypothesized that DMABEE has the potential to induce apoptosis. The necrosis inducing potential was also investigated. To test our hypothesis human monoblastoid U-937 cells were exposed to 10, 20, 40, 80, 120, 160, and 200 microM of DMABEE for 24, 48, and 72 h. At the culture end-points apoptotic and necrotic cells were detected by flow cytometry. DMABEE enhanced cell death by apoptosis and necrosis in U-937 cells in a dose-dependent fashion. The data support our hypothesis that DMABEE triggers death-signaling pathways.

Promotion of thyroid carcinogenesis by para-aminobenzoic acid in rats initiated with N-bis(2-hydroxypropyl)nitrosamine.

Sulfonamide analogues of para-aminobenzoic acid (PABA), a precursor of folate synthesis, have beneficial effects as antifolate, but thyroid peroxidase inhibition has been reported as a side effect that results in promotion of rat thyroid carcinogenesis. In the present study, effects of PABA itself on F344 rat thyroid carcinogenesis after initiation with N-bis(2-hydroxypropyl)nitrosamine (DHPN) were evaluated. In experiment 1, rats in groups 1-4 received a single subcutaneous injection of DHPN at 2800 mg/kg, and groups 5 and 6 received vehicle saline alone. From 1 week after DHPN initiation, rats in groups 2, 3, 4, and 6 were fed basal diet containing 0.25%, 0.5%, 1.0%, and 1.0% PABA, respectively, for 40 weeks. Rats in groups 1 and 5 received basal diet alone throughout the experiment. The final incidence of thyroid follicular cell adenomas and adenocarcinomas was significantly (p < 0.05 or 0.01) increased in groups 3 and 4 as compared to group 1. No thyroid tumors were found in groups 5 and 6. In experiment 2, animals in group 1 were fed basal diet alone, while groups 2 and 3 were given 0.5% and 1.0% PABA in the diet, respectively, for 2 weeks. Thyroid weights in group 3, and serum thyroid stimulating hormone level and proliferative activity of follicular cells in groups 2 and 3 were significantly (p < 0.05 or 0.01) elevated. In addition, the serum thyroxine level in group 3 was significantly (p < 0.05) depressed. These results clearly indicate that PABA exerts promotion/progression effects on rat thyroid carcinogenesis as a result of hypothyroidism followed by negative-feedback via the thyroid-pituitary axis.

Stress-induced apoptosis in sea urchin embryogenesis.

We find that early sea urchin embryos have the capability to induce programmed cell death, or apoptosis, in response to chemical and physical stress. Strongylocentrotus purpuratus embryos (fertilized, 4 cell, 16 cell, 64 cell, and early blastula) were exposed to known cytotoxins, in order to determine when apoptosis occurs naturally and in response to stress. Using cell permeability as an indicator of early stage apoptosis, caspase activation as a mid-stage indicator, and DNA fragmentation as a late stage indicator, we find that during the cleavage stage of embryogenesis apoptosis is almost completely absent. However, a statistically significant (p<0.001) rise in apoptosis in stressed embryos is evident around 24 h after fertilization, during the early blastula stage and shortly after hatching. Before this stage, exposed embryos show no statistically significant increases in apoptosis in comparison to the controls. This pattern of apoptosis in development is similar to that seen in lower vertebrate models in which stress-induced apoptosis occurs only around the mid-blastula transition. We conclude that apoptosis may be used to rid embryos of aberrant or damaged cells in early development, but this response is stage-dependant. Repair, rather than apoptosis, may be utilized during earlier stages, or alternatively, embryos exposed to such stressors may continue development with damaged cells and perhaps damaged DNA. Our continued studies will focus on these alternative hypotheses.

Interaction of a dental filling material eluate and membrane lipids.

The possibility that 4-N,N-dimethyl amino benzoic acid ethylester (DMABEE), a leachable lipophilic component of dental fillings, could interact with biological membranes was investigated. Interaction of DMABEE with phospholipids was studied by two methods: First, by determining the surface pressure/molecular area isotherms at 37degrees C of glycerophospholipids monolayers, using the Langmuir technique: and second, by phase transition parameters in liposomes of the same lipids, using differential scanning calorimetry (DSC). DMABEE clearly interacted, in a concentration-independent manner, with monolayers of saturated phosphatidylcholines (PC, i.e., markers of the outer membrane leaflet) and phosphatidylserines (PS, i.e., markers of the inner membrane leaflet). This interaction increased with increasing acyl length in the lipids and was greater with PC than with PS. These observations with monolayers were confirmed by the studies of liposomes of PC and PS.

Ca(2+)-calmodulin antagonist chlorpromazine and poly(ADP-ribose) polymerase modulators 4-aminobenzamide and nicotinamide influence hepatic expression of BCL-XL and P53 and protect against acetaminophen-induced programmed and unprogrammed cell death in mice.

Acetaminophen (AAP), the analgesic hepatotoxicant, is a powerful inducer of oxidative stress, DNA fragmentation, and apoptosis. The anti-apoptotic oncogene bcl-XL, and the pro-apoptotic oncogene p53 are two key regulators of cell cycle progression and/or apoptosis subsequent to DNA damage in vitro and in vivo. This study investigated the effect of AAP on the expression of these oncogenes and whether agents that modulate DNA fragmentation (chlorpromazine, CPZ) and DNA repair through poly(ADP-Ribose) polymerase (PARP) activity (4-AB: 4-aminobenzamide) can protect against AAP-induced hepatotoxicity by inhibiting oxidative stress, DNA fragmentation, and/or by altering the expression of bcl-XL and p53. In addition, the protective effect of supplemental nicotinamide (NICO), known to be depleted in cells with high PARP activity during DNA repair, is similarly evaluated. Male ICR mice (3 months old) were administered vehicle alone; nontoxic doses of 4-AB (400 mg/kg, ip), NICO (250 mg/kg, ip) or CPZ (25 mg/kg, ip), hepatotoxic dose of AAP alone (500 mg/kg, ip), or AAP plus one of the protective agents 1 h later. All animals were sacrificed 24 h following AAP administration. Serum alanine aminotransferase activity (ALT), hepatic histopathology and lipid peroxidation, DNA damage, and expression of bcl-XL and p53 (western blot analysis) were compared in various groups. All of the three agents significantly prevented AAP-induced liver injury, lipid peroxidation, DNA damage, and associated apoptotic and necrotic cell deaths, 4-AB being the most effective and NICO the least. Compared to control, there was a considerable decrease in bcl-XL expression, and an increase in p53 expression in AAP-exposed livers. The effect of AAP on bcl-XL was antagonized and that on p53 was synergized by the PARP-modulator 4-AB as well as NICO, whereas the endonuclease inhibitor CPZ was without effect on either bcl-XL or p53 expression. These results suggest that the hepatotoxic effect of AAP involves multiple mechanisms including oxidative stress, upregulation of endonuclease (or caspase-activated DNAse) and alteration of pro- and anti-apoptotic oncogenes. The observed antagonism of AAP-induced hepatocellular apoptosis and/or necrosis by modulators of multiple processes including DNA repair suggests the likelihood that a more effective therapy against AAP intoxication should involve a combination of antidotes.

Development of a highly sensitive in vitro phototoxicity assay using the SkinEthic reconstructed human epidermis.

The reconstituted human epidermis model SkinEthic was used to evaluate the phototoxicity of topically applied chemicals. For comparison with published data, we first tested a library of 13 nonphototoxic (NPT) and phototoxic (PT) compounds, applied onto SkinEthic reconstituted human epidermal tissues, in a protocol as close as possible to the one described by Liebsch using another skin tissue model. The results showed that, under these nonoptimized conditions, the SkinEthic model was already able to fully discriminate between known NPT and PT compounds. Furthermore, these epidermal tissues being highly resistant to UVA irradiation, it was possible to increase irradiation by (at least) 3-fold without decrease in tissue viability. In such conditions, the phototoxicity assay is much more sensitive, so that the model is expected to be of great interest for the detection not only of strong but also of weak phototoxic compounds.

Effects of berberine on arylamine N-acetyltransferase activity in human colon tumor cells.

Berberine was used to determine loss of viable cells and inhibition of arylamine Nacetyltransferase (NAT) activity in a human colon tumor (adenocarcinoma) cell line. The viable cells were determined by trypan blue exclusion under a light microscope. The NAT activity was measured by high performance liquid chromatography for the amounts of N-acetyl-2-aminofluorene (AAF), N-acetyl-p-aminobenzoic acid (N-Ac-PABA), and the remaining 2-aminofluorene (AF) and p-aminobenzoic acid (PABA). The viability and NAT activity in a human colon tumor cell line was inhibited by berberine in a dose-dependent manner, i.e., the higher the concentration of berberine, the higher the inhibition of NAT activity and cell death. The NAT activities measured in the intact human colon tumor cells were decreased over 50% by AAF and NAc-PABA production from acetylation of AF and PABA. The apparent values of Kmoff and Vmax of NAT from colon tumor cells were also inhibited by berberine in cytosols and in intact cells. This report is the first to show that berberine did affect human colon tumor cell NAT activity.

The photomutagenicity of fluoroquinolones and other drugs.

Induction of DNA damage as a consequence of exposure to UV light has been established as the major and still increasing cause of skin cancer. Absorption of the photon energy may be either directly by the DNA molecules (for wavelengths < 320 nm) or may be by endogenous or exogenous chemicals (sensitizers) with the potential of energy or electron transfer to DNA. Oxygen-mediated reactions (often called type II reactions) appear to be the most important mechanism since molecular oxygen is a good and abundant substrate for triplet excited sensitizers. Energy transfer to molecular oxygen is possible for wavelengths in the near UV and in the visible part of the solar spectrum since the energy of the excited oxygen molecule ((1)O2*) is comparatively low. A few light-absorbing pharmaceuticals have long been known to cause photo(geno)toxic effects. Notably psoralene and chlorpromazine derivatives have been established as photomutagens and the reaction mechanisms have been identified. The fluoroquinolone antibiotics have more recently been recognized as being photomutagenic. The type of DNA damage and the modulation by antioxidants indicate the involvement of reactive oxygen species (ROS) but other mechanisms are also reported at least for some derivatives. In routine genotoxicity studies we observed a photomutagenic activity of a compound under development as an anxiolytic agent in the Ames tester strain TA102 at 'normal laboratory illumination' conditions. Further investigations showed strong photogenotoxic activity in tests for gene mutations and chromosomal aberrations in mammalian cells. The compound proved to be a potent (1)O2-producer. The finding led to termination of development but in the course of studies several structural analogues have been tested for which structure activity relationships will be described. The relevance of photogenotoxic properties of drugs for predicting adverse effects in man will be discussed.

[Effect of para-aminobenzoic acid on the development of rat embryos when applied to pregnant females]. / Izuchenie vliianiia paraaminobenzoinoi kisloty na razvitie zarodyshei krys pri vozdeistvii na beremennykh samok.

In order to study the effects of para-aminobenzoic acid (PABA) on embryonic development, the pregnant rats were injected intraperitoneally daily with 0.3% PABA at 5 mg/kg (0.3 ml/200 g): in group 2 during the preimplantation period (days 1-6 of pregnancy), in group 3 during the period of organogenesis (days 6-16), and in group 4 during days 1-16. In group 5, PABA was injected intraperitoneally (at 15 mg/kg (0.3 ml/200 g, three times a day) during days 6-16 of pregnancy and in group 6, intragastrically as a suspension at 50 mg/kg during days 1-16. In the control (group 1), saline was injected intraperitoneally at 0.3 ml/200 g during days 1-16 of pregnancy. Autopsy of the females, counting of the number of yellow bodies and implantation sites and of the number of resorbed and died fetuses, and evaluation of development of the fetuses with an account of their mass, parieto-coccygeal size and placenta mass were performed on day 20 of pregnancy. Para-aminobenzoic acid at all tested doses does not exert a damaging effect and does not affect organogenesis. At doses 5 and 15 mg/kg, PABA does not affect growth but reduces the scattering of the extreme values of the parieto-coccygeal size and body mass, thus reflecting normalization of the growth of fetuses within the litter. At a dose of 50 mg/kg, the increase of body mass of the fetuses is insignificantly diminished (p < 0.05), which is usually normalized during postnatal development.