Abstract
Pituitary Prolactin (PRL) and Growth Hormone (GH) are separately controlled and sub-serve different purposes. Surprisingly, we demonstrate that extra-pituitary expression in the adult mammalian central nervous system (CNS) is coordinated at mRNA and protein levels. However this was not a uniform effect within populations, such that wide inter-individual variation was superimposed on coordinate PRL/GH expression. Up to 44% of individuals in healthy cohorts of mice and rats showed protein levels above the norm and coordinated expression of PRL and GH transcripts above baseline occurred in the amygdala, frontal lobe and hippocampus of 10% of human subjects. High levels of PRL and GH present in post mortem tissue were often presaged by altered responses in fear conditioning and stress induced hyperthermia behavioral tests. Our data define a common phenotype polymorphism in healthy mammalian brains, and, given the pleiotropic effects known for circulating PRL and GH, further consequences of coordinated CNS over-expression may await discovery.
Highlights
IntroductionThe growth hormone gene family includes growth hormone (GH) itself ( known as somatotrophin), prolactin (PRL) and the placental lactogens
The growth hormone gene family includes growth hormone (GH) itself, prolactin (PRL) and the placental lactogens
This phenotype polymorphism of the adult central nervous system (CNS) is common, being present in 7–44% of animals in selected cohorts (Table 3); it is often present in young animals and is not associated with any type of CNS neoplasia visible by light microscopy
Summary
The growth hormone gene family includes growth hormone (GH) itself ( known as somatotrophin), prolactin (PRL) and the placental lactogens. Since sharing residual similarities in their amino acid sequences these proteins (for simplicity referred to as GH and PRL, respectively) are thought to have arisen from an ancestral gene by duplication [1]; divergence of the PRL and GH lineages from this gene is inferred to have taken place some 400 million years ago [2, 3]. GH and PRL are single-copy genes in rodents, whereas there are 4 further GH-like genes in human (reviewed in [4]). GH and PRL are abundant products of the anterior pituitary, being produced by somatotroph and lactotroph cells respectively. Besides having endocrine effects on several target organs these polypeptide hormones have pleiotropic biological effects [5,6,7] and can enter the PLOS ONE | DOI:10.1371/journal.pone.0149410 February 19, 2016
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