A Pit-1 Binding Site Adjacent to E-box133 in the Rat PRL Promoter is Necessary for Pulsatile Gene Expression Activity

Recent findings on hyperprolactinemia and its pathological implications: a literature review

The prolactin hormone (PRL) is often secreted by lactotrophic cells of the anterior pituitary and has been shown to play a role in various biological processes, including breast feeding and reproduction. The predominant form of this hormone is the 23 kDa form and acts through its receptor (PRLR) on the cell membrane. This receptor is a member of the superfamily of hematopoietic/cytokine receptors. PRL also has a 16 kDa subunit with anti-angiogenic, proapoptotic, and anti-inflammatory effects which is produced by the proteolytic breakdown of this hormone under oxidative stress. Although the common side effects of hyperprolactinemia are exerted on the reproductive system, new studies have shown that hyperprolactinemia has a wide variety of effects, including playing a role in the development of autoimmune diseases and increasing the risk of cardiovascular disease, peripartum cardiomyopathy, and diabetes among others. The range of PRL functions is increasing with the discovery of multiple sites of PRL secretion as well as PRLR expression in various tissues. This review summarizes current knowledge of the biology of PRL and its receptor, as well as the role of PRL in human pathophysiology.

The circadian clock regulator Bmal1 affects traumatic brain injury in rats through the p38 MAPK signalling pathway

Traumatic brain injury (TBI) is still one of the main causes of death and disability worldwide. Bmal1 (brain and muscle Arnt-like protein-1) is the most central factor of the circadian rhythms that control life and cells. Studies have shown that Bmal1 is involved in inflammation, oxidative stress, vasodilation, glucose and lipid metabolism. This study explored the effect of Bmal1 on secondary brain injury after TBI in rats and the possible mechanism. We established a rat model of TBI induced by the free fall of a weight in rats. The Western blotting and immunofluorescence results showed that the Bmal1 levels decreased in the cerebral cortex after TBI, especially at 48 h. The effects of Bmal1 levels on rats after TBI were evaluated by brain oedema measurement, adhesive removal tests, behavioural tests, and TUNEL and FJC staining. We found that the recombinant Bmal1 protein increased Bmal1 levels after TBI and reduced brain oedema, neurobehavioural injury, somatosensory disturbances, and nerve cell necrosis and apoptosis. The ELISA results showed that Bmal1 overexpression could reduce the inflammatory factors IL-4 and TNF-α after TBI. In contrast, inhibiting Bmal1 expression had the opposite effect. The changes in Bmal1 levels were closely related to the phosphorylation of p38 MAPK after TBI. In conclusion, a decrease in Bmal1 after TBI may exacerbate pathological symptoms in vivo by activating p38 MAPK phosphorylation.