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A. M. PASCUAL-LEONE ANAL. REAL ACAD. FARM.

el momento actual, pero la hipótesis neuroendocrina de Tanner, elaborada para explicar el
control cerebral del crecimiento, en 1963, parece confirmarse, por los conocimientos que
tenemos hoy, en el control neural del apetito.

Palabras clave: Regulación del crecimiento.- Axis GH/IGFs e hipótesis neuroendrocina.

SUMMARY

Regulation of growth: GH/IGFs axis and hypothesis of tanner

Regulation of growth, both in fetal and neonatal stages, is absolutely dependent on
the energy balance. Growth is a complex process which permits both its retardation in
adverse circumstances and the accelerated catch up to reach standard values when the
conditions favor it. This precise regulation indicates the presence of a central control at the
brain level. The first step in the control of the energetic balance is the control of apetite,
which understanding is starting nowadays. Orexigenic and anorexigenic pathways produced
at the hypothalamus regulate the switch on or off respectively of the sensation of apetite.
Neuropeptide Y (NPY) secreted by the arcuate nucleus is the orexigenic compound most
interesting whereas leptin, secreted by the adipose tissue, is the physiological anorexigenic
endogenous substance. Both regulate apetite in a subtle manner involving complex
molecular mechanisms yet to unravel. There is ample evidence that leptin, which is the brain
sensor for the energetic balance, is also involved in the fetal growth when control of apetite
is not necessary. Both NPY and leptin are regulated by insulin in rodents. In humans, leptin
seems to be regulated by other metabolites; in particular, insulin-like growth factors (IGFs)
are excelent candidates for leptin regulation since they are secreted within the brain, regulate
somatic growth at the cartilage and their circulating levels decrease in conditions of
undernutrition while the brain IGFs receptors increase. Although much research is needed in
this area, the neuroendocrine hypothesis of Tanner, elaborated in 1963 to deliniate the brain
regulation of growth, stands today as the most plausible explanation for the control of
apetite and its role in mammal growth.

Key words: Regulation of Growth.- GH/IGFs axis and neuroendrocrine hypothesis.

1.- INTRODUCCIÓN

En periodo embriológico, el programa genético es primorlcial para el
crecimiento, pero, aún entonces, determinados factores, llamados
ambientales, son capaces de influir y modularlo de forma decisiva. Los

2