Parental Preconception and Pre-Hatch Exposure to a Developmental Insult Alters Offspring's Gene Expression and Epigenetic Regulations: An Avian Model.

Parental exposure to insults was initially considered safe if stopped before conception. In the present investigation, paternal or maternal preconception exposure to the neuroteratogen chlorpyrifos was investigated in a well-controlled avian model (Fayoumi) and compared to pre-hatch exposure focusing on molecular alterations. The investigation included the analysis of several neurogenesis, neurotransmission, epigenetic and microRNA genes. A significant decrease in the vesicular acetylcholine transporter (SLC18A3) expression was detected in the female offspring in the three investigated models: paternal (57.7%, p < 0.05), maternal (36%, p < 0.05) and pre-hatch (35.6%, p < 0.05). Paternal exposure to chlorpyrifos also led to a significant increase in brain-derived neurotrophic factor (BDNF) gene expression mainly in the female offspring (27.6%, p < 0.005), while its targeting microRNA, miR-10a, was similarly decreased in both female (50.5%, p < 0.05) and male (56%, p < 0.05) offspring. Doublecortin's (DCX) targeting microRNA, miR-29a, was decreased in the offspring after maternal preconception exposure to chlorpyrifos (39.8%, p < 0.05). Finally, pre-hatch exposure to chlorpyrifos led to a significant increase in protein kinase C beta (PKCß; 44.1%, p < 0.05), methyl-CpG-binding domain protein 2 (MBD2; 44%, p < 0.01) and 3 (MBD3; 33%, p < 0.05) genes expression in the offspring. Although extensive studies are required to establish a mechanism-phenotype relationship, it should be noted that the current investigation does not include phenotype assessment in the offspring.

Determination of Annual Plasma Hormone Levels Associated with Reproduction in Long-Day Breeding Domestic Geese.

This paper examines the dynamics of circulating hormone changes connected with reproduction in geese during the annual period related to gonad morphometry. One hundred geese were examined. The levels of prolactin (PRL), triiodothyronine (T3), thyroxine (T4), testosterone (T), progesterone (P4) and estradiol (E2) were estimated. In both sexes, PRL level patterns fit a quadratic trend with elevations in the post-breeding and the second half of the breeding-laying periods. During these periods, differences in the PRL level between sexes were noted. In ganders, increased PRL levels during the laying period occurred earlier compared to in female geese. Cubic trends for T and E2 in ganders and quadratic for T, P4, and E2 in female geese were observed. PRL was negatively correlated with T in both sexes and with P4 and E2 in female geese. A higher level of T3 and variation in T4 in ganders with a quartic trend in ganders vs. a quadratic in female geese were noted. Patterns of PRL, T, and E2 suggested that the breeding-laying period in ganders may be shorter than in female geese. These findings will be used to explore experimental manipulations of the endocrine axis to increase synchronisation of both sexes.

The effect of parachlorophenylalanine treatment on the activity of gonadal and lactotrophic axes in native Polish crested chickens stimulated to broodiness.

Brooding behavior, a common characteristic of native breeds of the domestic chicken, is marked by elevated prolactin (PRL) levels, which is necessary for incubation and connected with changes in hypothalamic-pituitary-gonadal axis activity. Evidence indicates the serotoninergic system is a potent modulator of PRL secretion. The objective of this study is to investigate whether blocking serotonin synthesis with parachlorophenylalanine (PCPA) prevents incubation behavior in native Polish crested chickens. In addition, we examined the effect of PCPA on the gene expression of the gonadal and lactotrophic axes. Birds were stimulated to broodiness by artificial eggs in nests. At 34 wk of age (April: spring period), the hens were divided into 2 groups (14 hens in each group): control and PCPA-treated (50 mg/kg BW) group. After 5 wk of treatment, the artificial eggs were removed from the nests. Egg production, incubation activity, and levels of plasma ovarian steroids progesterone (P4), testosterone (T), estradiol (E2), and PRL were examined. At the end of the experiment (45 wk of age, June: summer period), ovarian characteristics and mRNA gene expression of gonadal (gonadotropin-releasing hormone [GnRH] I, luteinizing hormone [LH] ß, follicle-stimulating hormone [FSH] ß) and lactotrophic (vasoactive intestinal peptide [VIP], PRL) axes were measured by quantitative real-time PCR. Incubation activity was observed in the hens of both groups but with lower frequency in PCPA-treated birds. Moreover, the PCPA group had a higher cumulative egg production than the controls. During the first six and 8 wk of the experiment, levels of P4 and E2, respectively, were similar in both groups, but all concentrations increased in the PCPA-treated hens after this period. In addition, increased GnRH-I, LHß, and FSHß and decreased VIP mRNA expression was observed in the PCPA group compared with the controls. There were no differences in PRL mRNA expression, the PRL level, and ovarian morphometry between the 2 groups. These results indicate that blockage of serotonin synthesis by PCPA does not effectively prevent incubation in native Polish crested chickens. However, treatment with PCPA increased gonadal axis activity and improved reproductive performance.