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Published on: January 10, 2025
Different modes of GH administration influence gene expression in the male rat brain
Marion Walser1, Linus Schiöler1, Jan Oscarsson1
1Laboratory of Experimental EndocrinologyDepartment of Internal Medicine, The Sahlgrenska Academy, Sahlgrenska University Hospital, University of Gothenburg, Blå Stråket 5, SE-413 45 Gothenburg, SwedenDepartment for Public Health and Community MedicineThe Sahlgrenska Academy, University of Gothenburg, Gothenburg, SwedenAstraZeneca R&DSE-431 83 Mölndal, Gothenburg, SwedenInstitute for Neuroscience and PhysiologyThe Sahlgrenska Academy, Center for Brain Repair and RehabilitationDepartment of Primary Health CareInstitute of Medicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Abstract:
The endogenous secretion pattern in males of GH is episodic in rats and in humans, whereas GH administration is usually even. Different types of GH administration have different effects on body mass, longitudinal bone growth, and liver metabolism in rodents, whereas possible effects on brain plasticity have not been investigated. In this study, GH was administered as a continuous infusion or as two daily injections in hypophysectomized male rats. Thirteen transcripts previously known to respond to GH in the hippocampus and parietal cortex (cortex) were assessed by RT-PCR. To investigate the effects of type of GH administration on several transcripts with different variations, and categories of transcripts (neuron-, glia-, and GH-related), a mixed model analysis was applied. Accordingly, GH injections increased overall transcript abundance more than GH infusions (21% in the hippocampus, P<0.001 and 10% in the cortex, P=0.09). Specifically, GH infusions and injections robustly increased neuronal hemoglobin beta (Hbb) expression significantly (1.8- to 3.6-fold), and GH injections were more effective than GH infusions in increasing Hbb in the cortex (41%, P=0.02), whereas a 23% difference in the hippocampus was not significant. Also cortical connexin 43 was higher in the group with GH injections than in those with GH infusions (26%, P<0.007). Also, there were differences between GH injections and infusions in GH-related transcripts of the cortex (23%, P=0.04) and glia-related transcripts of the hippocampus (15%, P=0.02). Thus, with the exception of Hbb there is a moderate difference in responsiveness to different modes of GH administration.
