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Interaction between Prolactin and the Hypothalamic-Pituitary-Adrenal (HPA) axis

Kalyani, Manu
http://rave.ohiolink.edu/etdc/view?acc_num=miami1397233916

Abstract Details

2014, Doctor of Philosophy, Miami University, Zoology.
We investigated the interaction between prolactin (PRL) and the HPA axis. A physiologically relevant, hyperprolactinemic model, i.e. postpartum female rats, or PRL knockout mice were used. Animals housed with or separated from their pups for 1 or 24 hours or 8 days were acutely stressed. Circulating PRL and corticosterone (CORT) and PRL-R mRNA in the choroid plexus were determined. PRL returned to pre-pregnancy values by one hour after pup removal. The HPA axis response was restored after 24 hours of separation, although basal CORT levels remained elevated for 8 days after terminating lactation. PRL-R expression decreased 24 h after pup separation, but returned to pre-pregnancy levels by 8 days. Stress-induced HPA axis activation occurred only when PRL-R expression levels were similar to or lower than levels in virgins indicating PRL-R up-regulation contributes to an attenuated HPA response. The sustained, elevated basal CORT levels suggest the metabolic demands and/or stress of lactation persist in the absence of suckling. Additionally, differential effects of gender, diet and PRL on HPA axis activation were studied using wild-type (wt) and PRL knockout (KO) mice. Male and female mice fed normal chow (C) or high-fat diet (HFD) for 12 weeks were acutely stressed. CORT levels were quantified under basal conditions, during stress and at the time of sacrifice. Serial sampling acted as a non-specific stressor, regardless of gender, genotype or diet; PRL dampened this response in males only. HFD increased body weight and fat accumulation in males, but not in females, regardless of genotype. In chow fed animals, stress increased CORT in both males and females, regardless of genotype, indicating that PRL is not involved in activating the HPA axis. HFD increased PRL-R mRNA in wt and KO females, but only in wt males indicating factors other than PRL regulate PRL-R expression in females. HFD increased leptin levels only in wt males and females, suggesting PRL influences leptin regulation. Overall, the PRL profile in the postpartum females affects HPA axis activity. Further, there is a gender difference in HPA axis regulation during stress when animals are fed a HFD and PRL is involved in this regulation.
Phyllis Callahan, PhD (Committee Chair)
James Janik, PhD (Committee Co-Chair)
91 p.
Biology; Endocrinology; Neurosciences
Lactation, Corticosterone, PRL receptors, High-fat diet, PRL knockout mice, Gender differences, Restraint stress, Leptin

Recommended Citations

Citations

  • Kalyani, M. (2014). Interaction between Prolactin and the Hypothalamic-Pituitary-Adrenal (HPA) axis [Doctoral dissertation, Miami University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=miami1397233916

    APA Style (7th edition)

  • Kalyani, Manu. Interaction between Prolactin and the Hypothalamic-Pituitary-Adrenal (HPA) axis . 2014. Miami University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=miami1397233916.

    MLA Style (8th edition)

  • Kalyani, Manu. "Interaction between Prolactin and the Hypothalamic-Pituitary-Adrenal (HPA) axis ." Doctoral dissertation, Miami University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=miami1397233916

    Chicago Manual of Style (17th edition)

miami1397233916
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© 2014, all rights reserved.
This open access ETD is published by Miami University and OhioLINK.
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