Molecular basis of growth hormone daily mRNA and protein synthesis in rats

Publication date: 15 August 2018Source: Life Sciences, Volume 207Author(s): T. de Castro Barbosa, R.B. Salgueiro, C. Serrano-Nascimento, F.G. Amaral, J. Cipolla-Neto, M.T. NunesAbstractAimsDaily and seasonal rhythms coordinate the endocrine and metabolic functions. The pituitary gland is the master regulator of several endocrine activities, and its function is classically regulated by endocrine signals from its target glands as well as from the hypothalamus. The growth hormone (GH) produced and secreted by the anterior pituitary presents a pulsatile secretion throughout the 24-hour cycle. However, the molecular mechanisms regulating the daily pattern of GH secretion are still unclear. Herein we investigated whether circadian GH mRNA and protein synthesis is modulated by acute adjustments in the stability and expression of GH mRNA.Main methodsGH mRNA and protein content were evaluated by real-time PCR and Western blotting, respectively, in pituitary gland of rats euthanized every 3 h during a 24-h period at the Zeitgeber times (ZT3 to ZT24). The GH mRNA poly(A) tail length was determined by RACE-PAT assay.Key findingsWe identified two main peaks of GH mRNA level in the pituitary gland of rats; one in the middle of the light-cycle and another in the middle of the dark-cycle. The latter was associated with an increase in pituitary GH protein content. Interestingly, an increment in the poly(A) tail length of the GH transcript was observed in association to reduced migration rat...

Source: Life Sciences - July 11, 2018 Category: Biology Source Type: research