Some hypothalamic hamartomas contain transforming growth factor alpha, a puberty-inducing growth factor, but not luteinizing hormone-releasing hormone neurons

Activation of LH-releasing hormone (LHRH) secretion, essential for the init iation of puberty, is brought about by the interaction of neurotransmitters and astroglia-derived substances. One of these substances, transforming gr owth factor alpha (TGF alpha), has been implicated as a facilitatory compon ent of the glia-to-neuron signaling process controlling the onset of female puberty in rodents and nonhuman primates. Hypothalamic hamartomas (HH) are tumors frequently associated with precocious puberty in humans. The detect ion of LHRH-containing neurons in some hamartomas has led to the concept th at hamartomas advance puberty because they contain an ectopic LHRH pulse ge nerator. Examination of two HH associated with female sexual precocity reve aled that neither tumor had LHRH neurons, but both contained astroglial cel ls expressing TGF alpha and its receptor. Thus, some HH may induce precocio us puberty, not by secreting LHRH, but via the production of trophic factor s-such as TGF alpha-able to activate the normal LHRH neuronal network in th e patient's hypothalamus.