The role of endogenous insulin-like growth factors-1 and -2 on
lactation in rats
G.S.G. Spencer, S.C. Hodgkinson, C.J. Berry
Growth Physiology, Ruakura Agricultural Centre, Hamilton, New
Zealand
Proceedings of the New Zealand Society of Animal Production. 1995,
55: 26-27
The role of endogenous insulin-like growth factor (IGF)-1 and -2 on
lactation in rats was examined by passive immuno-neutralization of
Wistar rats. In one study, the rats were given immunoglobulins raised
in sheep against either IGF-1, IGF-2 or non-specific sheep
immunoglobulins by daily s.c. injection throughout pregnancy. In a
second series of experiments, the dams were passively immunized by i.p.
the milk yield calculated from the pup weight and weight gain.
Immunoneutralization of either IGF-1 or IGF-2 in the mother during
pregnancy had no effect on the mean birth weight or postnatal growth
rate of the pups. Milk yield from rats treated during pregnancy
(21.5+/- 1.2 and 20.3 +/- 0.9 g/day for anti-IGF and anti-IGF-2,
respectively) compared with control rats given normal sheep serum (231.9
+/- 1.1 g/day) was also not significantly different. Similarly, passive
immunization against either IGF-1 (22.2+/- 0.9 g/d) or IGF-2 (18.0 +/-
2.0 g/d) during lactation also did not affect milk yields compared with
controls (24.9 +/- 1.0 g/day). These data do not support a significant
role of endogenous IGF's in regulating milk production in lactating
rats.
Keywords: NZSAPAB;
insulin-like growth factors; immunoneutralization; lactation;
pregnancy; rat
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Last Updated 25-01-1997
