Changes in the Expression of the Prolactin Receptor (PRLR) Gene in Different Physiological Stages in the Mammary Gland of the Iranian Adani Goat

Postpartum Fatigue and Inhibited Lactation

Background: Postpartum fatigue is a common disorder worldwide and affects both physical and mental functioning. In breastfeeding women, Prolactin (PRL) is not only involved in immunoregulation, but also responsible for lactation. Prolactin levels in women with chronic fatigue are higher than normal, but a chronic fatigue state inhibits postpartum lactation in humans. Objectives: This paper explored the inhibition mechanism of lactation by postpartum fatigue in rats. Methods: Postpartum fatigue models were built by forcing mother rats to stand in water and divided into 3-hour, 9-hour and 15-hour per day fatigue groups according to the underwater time. Mother rats and their offspring were reunited in a dry cage for 90 minutes every 3 hours for feeding. The expression of PRL, PRL receptor (PRLR), Janus Kinase 2 (JAK 2), and Signal transducers and activators of transcription 5 (STAT5) mRNA were analyzed and the microstructure of mammary gland were observed under light and electron microscopy. Results: The expression of pituitary PRL mRNA and its downstream signaling pathway JAK2 and STAT5 mRNA were down-regulated in the severe postpartum fatigue rats. PRL mRNA responses were dose-related to duration of fatigue. The expression of PRLR mRNA increased. Postpartum fatigue led to functional degeneration of mammary gland. The breast lobules were shrunk and the number of alveoli were decreased. Few milk protein granules and fat droplets were observed in the cytoplasm under transmission electron microscope. Conclusion: Postpartum fatigue inhibits the lactation by down-regulating the expression of PRL and PRL-dependent signaling pathway in rats.

Molecular characterization and an 80-bp indel polymorphism within the prolactin receptor (PRLR) gene and its associations with chicken growth and carcass traits

The prolactin receptor (PRLR), a type I cytokine receptor, must bind prolactin (PRL) to act on target cells to mediate various physiological functions, including reproduction and lactation. This study identified an 80-bp insertion/deletion (indel) polymorphism in the 3'-untranslated region (3'-UTR) of the chicken PRLR gene in 3736 individuals from 15 breeds and analyzed its associations with growth and carcass traits in an F₂ resource population. The results of the association analysis indicated that the 80-bp indel polymorphism was significantly (P < 0.05) or very significantly (P < 0.01) associated with multiple growth and carcass traits, such as body weight, leg weight, and shank length. In addition, we found that during the breeding process of commercial laying hens and commercial broilers, the 80-bp indel locus was artificially selected for the II genotype. Together, our findings reveal that this 80-bp indel polymorphism has potential as a new molecular marker for marker-assisted selection of chicken growth and carcass traits.

Prolactin Receptor Isoforms as the Basis of Tissue-Specific Action of Prolactin in the Norm and Pathology

The review describes functional and structural features of different isoforms of prolactin receptor, mechanisms of signaling pathway activation, and molecular messengers involved in the transmission and termination of signal from the prolactin receptor isoforms. Changes in the ratio between prolactin receptor isoforms, key mediators of prolactin signal transduction and termination in various organs and tissues, are analyzed. Special attention is given to the role of molecular mediators and the ratio between the isoforms in normal physiological functions and pathologies. Approaches for therapeutic correction of prolactin signaling impairments are discussed.

Differential Expression of the Alpha S1 Casein and Beta-Lactoglobulin Genes in Different Physiological Stages of the Adani Goats Mammary Glands

Background

Milk proteins genes have been the focus of the researches as the candidate target genes that play a decisive role when animal breeding is desired.

Objectives

In the present study, the transcriptional levels of Beta-lactoglobulin (BLG) and Alpha S1 casein (CSN1S1) genes were investigated during prenatal, milking and drying times in mammary glands of the Adani goats which showed high and low breeding values.

Materials and Methods

The breeding values of the animals were estimated first by applying multi-trait random regression model. Using the biopsy gun, the mammary gland samples were taken and real-time PCR was applied to search the expression of the genes. Fixed factors of the model were the breeding value groups, sampling times and their interactions.

Results

The interactions were significant for both genes. At milking time, the high breeding value group exhibited more transcriptional levels for BLG and less transcriptional levels for CSN1S1 gene compared with the low breeding value group. The expression patterns of these genes were also different between the two breeding value groups. The maximum level of BLG and CSN1S1 transcriptions were found to occur at drying time.

Conclusions

A difference in the gene expression was observed between the two groups which indicate the change in the nucleotide sequence for transcription factor binding sites, or miRNA binding sites, otherwise in the coding regions. Therefore, the variations in the coding and promoter regions of this gene should be investigated in the further studies.