Role of thymulin on the somatotropic axis in vivo

REGGIANI PC; MARTINES E; CAMIHORT GA; POCH B; GOYA RG; CONSOLE GM

LIFE SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2012 vol. 91 p. 166 - 171

0024-3205

Aims: There is clear evidence for the existence of a bi-directional thymus–somatotropic axis and several studies sug- 22 gest that the thymic peptide thymulinmay be involved in this communication.We undertook to assess the impact 23 of serum thymulin immunoneutralization in C57BL/6 mice and that of neonatal thymulin gene therapy (NTGT) in 24 nude mice on body weight (BW) gain and on the histomorphometric profile of the somatotrope population. 25 Mainmethods: Immunoneutralization of thymulinwas done frompostnatal day 1 to 35 by i.p. injections of rab- 26 bit anti-thymulin serum(α-FTS) and normal rabbit serum(NRS) in controls. NTGTwas implemented in nudes 27 using an adenoviral vector expressing a synthetic gene for thymulin (RAd-FTS). On postnatal day 1, heterozy- 28 gous (nu/+) and homozygous (nu/nu) pups received a single bilateral i.m. injection either RAd-FTS or 29 RAd-GFP (a control vector expressing green fluorescent protein). BW gain was recorded and at the end of 30 the study the pituitarieswere immunostained for growth hormone (GH). SerumGH and thymulinwere deter- 31 mined by radioimmunoassay and bioassay, respectively. 32 Key findings: Thymulin immunoneutralization induced a significant decrease in BW gain, serum GH and 33 somatotrope cell density as well as an increase in somatotrope cell size. NTGT markedly increased BW gain, 34 serum thymulin (Pb0.01) and somatotrope cell and volume density in nu/nu mice. 35 Significance: Our results suggest that thymulin plays a relevant physiological role on the thymus–somatotropic 36 axis in mice. 37 © 2012 Published by Elsevier