Abstract:

Objective To observe the effects of recombinant human growth hormone （rh-GH） on depressive-like behavior in mice with chronic restraint stress （CRS）， and to discuss its possible mechanism. Methods The CRS method was used to establish an animal model of depression； a total of 45 mice were didided into control group （non-modeled， n=15）， and CRS model group （modeled， n=30） the sucrose preference test （SPT） was used to detect the sucrose preference rate of the mice； the tail suspension test （TST） was used to detect the immobility time of the mice； the open field test （OFT） was used to detect the total moving distance of the mice within 5 min and the time spent in the central area. The CRS mice were randomly divided into CRS model+saline group and CRS model+rh-GH group（n=10）； the mice in CRS model+saline group were injected with normal saline； the mice in CRS model+rh-GH group were subcutaneously injected with rh-GH daily for 1 month； the peripheral blood of the mice was collected before and after intervention to detect the expression levels of growth hormone （GH） and insulin-like growth factor Ⅰ （IGF-Ⅰ） proteins in serum； after all behavioral experiments， the hippocampus tissue was taken to detect the expression level of synapsin-1 （SYN-1） protein in the tissue of the mice. Results Compared with control group， the body weight of the mice in CRS model group was significantly decreased （P<0.01）， the sucrose preference rate in SPT was significantly decreased （P<0.01）， the immobility time in TST was significantly prolonged （P<0.01）； in OFT， the total moving distance of mice showed no significant change （P>0.05）， while the time spent in the central area was significantly shortened （P<0.05）. Compared with control group， the expression levels of GH and IGF-Ⅰ proteins in serum of the mice in CRS model group were significantly decreased （P<0.01）. Compared with CRS model+saline group， the sucrose preference rate in SPT of the mice in CRS model+rh-GH group was significantly increased （P<0.01）， the immobility time in TST was significantly shortened （P<0.05）， the total moving distance in OFT showed no significant difference （P>0.05）， and the time spent in the central area was significantly increased （P<0.01）. Compared with model+saline group， the expression levels of GH and IGF-I proteins in serum of the mice in CRS model+rh-GH group were significantly increased （P<0.01）. Compared with model group， the expression level of SYN-1 protein in hippocampus tissue of mice in drug-treated model group was significantly increased （P<0.05）. Conclusion rh-GH has ameliorative effects on depressive-like behavior induced by chronic restraint stress in mice， and its mechanism may be associated with regulation of the GH/IGF-Ⅰ axis and increased expression of SYN-1 in hippocampus tissue.

Key words: Depressive-like behavior, Recombinant human growth hormone, Insulin-like growth factor Ⅰ, Synapsin-1, Chronic restraint stress