Prapaporn Kopsombut

Endocrine disruptive actions of inhaled benzo(a)pyrene on ovarian function and fetal survival in fisher F-344 adult rats.

This study evaluated the effect of inhaled BaP on female reproductive function. Rats were exposed to 50, or 75 or 100 μg BaP/m(3), 4 h a day for 14 days via inhalation. Plasma E(2), P(4), LH and FSH concentrations were determined. Ovarian BaP metabolism and aryl hydrocarbon hydrolase (AHH) activity at proestrus were determined and fertility evaluations were conducted. Ovulation rate and number of pups/litter were reduced in rats exposed to 100 μg BaP/m(3) compared with other treatment and control groups. Plasma concentrations of E(2), and LH were significantly reduced at proestrus in BaP-exposed versus those of controls whereas those of P(4) were significantly reduced at diestrus I. The activity of AHH in ovarian and liver tissues and concentrations of BaP 7,8-diol and BaP 3,6-dione metabolites increased in an exposure concentration-dependent manner. These data suggest that exposure of rats to BaP prior to mating contributes to reduced ovarian function and fetal survival.

Stress reticulocytes lose transferrin receptors by an extrinsic process involving spleen and macrophages

As they mature into erythrocytes during normal erythropoiesis, reticulocytes lose surface transferrin receptors before or concurrently with reticulin. Exosome release accounts for most of the loss of transferrin receptors from reticulocytes. During erythropoietic stress, reticulocytes are released early from hematopoietic tissues and have increased reticulin staining and transferrin receptors. Flow cytometry of dually stained erythrocytes of mice recovering from phlebotomy demonstrated delayed loss of reticulin and transferrin receptors during in vitro maturation compared to in vivo maturation, indicating that an in vivo process extrinsic to the reticulocytes facilitates their maturation. Splenectomy or macrophage depletion by liposomal clodronate inhibited in vivo maturation of reticulocytes and increased the numbers of reticulin‐negative, transferrin receptor‐positive cells during and after recovery from phlebotomy. This reticulin‐negative, transferrin receptor‐positive population was rarely found in normal mice. Transmission electron microscopy demonstrated that the reticulin‐negative, transferrin receptor‐positive cells were elongated and discoid erythrocytes, but they had intracellular and surface structures that appeared to be partially degraded organelles. The results indicate that maturation of circulating stress reticulocytes is enhanced by an extrinsic process that occurs in the spleen and involves macrophage activity. Complete loss of reticulin with incomplete loss of surface transferrin receptors in this process produces a reticulin‐negative, transferrin receptor‐positive erythrocyte population that has potential utility for detecting prior erythropoietic stresses including bleeding, hemolysis and erythropoietin administration, even after recovery has been completed. Am. J. Hematol. 91:875–882, 2016.