Time-dependent reduction of structural complexity of the buccal epithelial cell nuclei after treatment with silver nanoparticles.

Recent studies have suggested that silver nanoparticles (AgNPs) may affect cell DNA structure in in vitro conditions. In this paper, we present the results indicating that AgNPs change nuclear complexity properties in isolated human epithelial buccal cells in a time-dependent manner. Epithelial buccal cells were plated in special tissue culture chamber / slides and were kept at 37°C in an RPMI 1640 cell culture medium supplemented with L-glutamine. The cells were treated with colloidal silver nanoparticles suspended in RPMI 1640 medium at the concentration 15 mg L⁻¹. Digital micrographs of the cell nuclei in a sample of 30 cells were created at five different time steps: before the treatment (controls), immediately after the treatment, as well as 15 , 30 and 60 min after the treatment with AgNPs. For each nuclear structure, values of fractal dimension, lacunarity, circularity, as well as parameters of grey level co-occurrence matrix (GLCM) texture, were determined. The results indicate time-dependent reduction of structural complexity in the cell nuclei after the contact with AgNPs. These findings further suggest that AgNPs, at concentrations present in today's over-the-counter drug products, might have significant effects on the cell genetic material.

Pituitary and adrenal glands in neonatal rats studied by metopirone (Su4885).

One half of each litter of the 2- and 7-day-old rats was injected twice daily for 3 consecutive days with 15 mg/100 g body weight of metopirone (MET) in 0.05 ml of saline, and the remaining littermates with saline only. At the ages of 5 and 10 days, one half of the pups was sacrificed immediately, and the second half 20 min after s.c. injection of histamine as a stressor. MET depressed body weight and induced adrenal hypertrophy in the 5- and 10- day-old rats, and pituitary hypertrophy in the 5-day-old rats only. In resting condition the adrenal glands of the 5-day-old rats treated with MET contained less corticosterone (determined fluorometrically) than the 5-day-old control and the 10-day-old pups treated also with MET. Furthermore, neonatal MET treatment induced (histamine) stress response by the increase in adrenal corticosterone content in the 10-day-old rats, and by the increase in corticosterone content in plasma in both ages. The results indicate high sensitivity of the young neonatal rats to hormonal manipulations. They also yield additional support to the concept of functional integrity of the hypothalamo-pituitary-adrenocortical system in neonatal rats, and to the flexibility of the postnatal developmental pattern of stress response.

Differential effect of pre- and postnatal litter size reduction on body weight and development of stress response in the rat.

The postnatal development of pups belonging to the small, prenatally reduced litters (PRN) was compared to that of pups of the postnatally reduced litters (PST) and to that of pups of intact, normal-size litters (CON). Body adrenal and pituitary weight gain as well as maturation of the pituitary-adrenal system were enhanced in the PRN and PST pups as compared to the CON pups in the 3 postnatal weeks. However, significant differences in some data between the PRN and PST pups were found, indicating the more pronounced beneficial effect of the prenatal reduction of litter size. The postnatal litter size reduction abolished the weight gain of the testes. The prenatal reduction of litter size resulted in a similar, although less pronounced negative effect.

Effects of pre- and postnatal litter size reduction on development and behavior of rat offspring.

Litter size was reduced to 2-5 rat pups either prenatally by unilateral maternal oviduct ligation (Group PRN) or postnatally by removing pups (Group PST). Normal size litters (8-10 pups) of sham ligated (SHM) and intact (CON) mothers served as controls. Weights at 30 days were increased by prenatal or postnatal reduction and reduced by prenatal stress (SHM); the sex difference in weight was most pronounced in PRN rats. At 75 days PRN rats were heaviest, with no differences between the other groups. Relative ovarian weights were reduced in PRN females and absolute testes weights increased in PST males. The PRN and SHM females had smaller relative adrenal weights than CON and PST females. Open-field activity was generally increased by prior avoidance conditioning and effects of treatments were found only in groups tested after avoidance-conditioning: PRN and SHM rats were more active than PST and CON rats, particularly on Days 1 (SHM) and 4 (SHM and PRN) of testing. Passive-avoidance behavior of PRN rats was also more susceptible to previous test experience: they emerged more slowly if they had prior open-field experience. The PST animals, in contrast, emerged more rapidly after prior test experience. Plasma corticosterone levels and shuttlebox conditioning and extinction were unaffected by treatments.

Steroidogenesis of the fetal adrenal gland in vitro: influence of metopirone applied in vivo and in vitro.

In vitro conversion of 4-14C-progesterone into corticosteroids in the adrenal glands of rat fetuses treated with Metopirone (Su 4885) on the last day of intrauterine development was studied. After a 1-hr incubation of the adrenal glands of fetuses injected with Metopirone, hydroxylation of progesterone into corticosterone (B), 18-hydroxycorticosterone (18-OH-B) and 18-hydroxy-11-deoxycorticosterone (18-OH-DOC) decreased and the synthesis of 11-deoxycorticosterone increased. Following preincubation of the fetal adrenal glands and 1-hr incubation with Metopirone, hydroxylation of progesterone into DOC increased and the synthesis of B decreased. Preincubation and a 2-hr incubation with Metopirone caused a decrease in the synthesis of B, 18-OH-B and 18-OH-DOC and an increase in DOC. The results constitute direct evidence of the ability of the fetal adrenal glands to synthesize all corticoids and indicate that most probably corticoids are synthesized by the fetal adrenal glands in the same way as in the adrenals of adult animals.

Failure of the metopirone (Su4885) suppressed fetal adrenal glands to maintain corticosterone concentration of adrenalectomized pregnant rats.

Plasma corticosterone concentrations were measured following adrenalectomy of pregnant rats on the last day of gestation. Plasma corticosterone concentrations decreased 40 and 60 min after adrenalectomy by 36 and 32%, respectively, and regained the preoperative concentration 2 h following operation. When the fetuses were injected with an inhibitor of 11beta-steroid hydroxylase (Su4885) plasma corticosterone concentrations decreased 40, 60 and 120 min following adrenalectomy by 63, 67 and 71%, respectively. The results strongly suggest that the fetal adrenal glands are the source of plasma corticosterone in adrenalectomized pregnant rats.