Transforming growth factor-alpha gene expression in the hypothalamus is developmentally regulated and linked to sexual maturation.
ABSTRACT Hypothalamic injury causes female sexual precocity by activating luteinizing hormone-releasing hormone (LHRH) neurons, which control sexual development. Transforming growth factor-alpha (TGF-alpha) has been implicated in this process, but its involvement in normal sexual maturation is unknown. The present study addresses this issue. TGF-alpha mRNA and protein were found mostly in astroglia, in regions of the hypothalamus concerned with LHRH control. Hypothalamic TGF-alpha mRNA levels increased at times when secretion of pituitary gonadotropins--an LHRH-dependent event--was elevated, particularly at the time of puberty. Gonadal steroids involved in the control of LHRH secretion increased TGF-alpha mRNA levels. Blockade of TGF-alpha action in the median eminence, a site of glial-LHRH nerve terminal association, delayed puberty. These results suggest that TGF-alpha of glial origin is a component of the developmental program by which the brain controls mammalian sexual maturation.
Article: Infundibular tanycytes as modulators of neuroendocrine function: hypothetical role in the regulation of the thyroid and gonadal axis.[show abstract] [hide abstract]
ABSTRACT: Tanycytes comprise a heterogeneous population of specialized cells of glial origin that line the floor and ventrolateral walls of the third ventricle between the rostral and caudal limits of the hypothalamic median eminence. While morphologic and ultrastructural features suggest a role as barrier cells, creating separate compartments between the cerebrospinal fluid, median eminence and hypothalamus, tanycytes likely have multiple other important functions that have yet to be fully elucidated. Possibilities to consider are a role in neuroendocrine regulation including modulation of the hypothalamic-pituitary-thyroid axis during fasting and infection, regulation of reproductive function, particularly in seasonal breeders, and in feeding.Acta bio-medica: Atenei Parmensis 02/2007; 78 Suppl 1:84-98.
Article: Function-related structural plasticity of the GnRH system: a role for neuronal-glial-endothelial interactions.[show abstract] [hide abstract]
ABSTRACT: As the final common pathway for the central control of gonadotropin secretion, GnRH neurons are subjected to numerous regulatory homeostatic and external factors to achieve levels of fertility appropriate to the organism. The GnRH system thus provides an excellent model in which to investigate the complex relationships between neurosecretion, morphological plasticity and the expression of a physiological function. Throughout the reproductive cycle beginning from postnatal sexual development and the onset of puberty to reproductive senescence, and even within the ovarian cycle itself, all levels of the GnRH system undergo morphological plasticity. This structural plasticity within the GnRH system appears crucial to the timely control of reproductive competence within the individual, and as such must have coordinated actions of multiple signals secreted from glial cells, endothelial cells, and GnRH neurons. Thus, the GnRH system must be viewed as a complete neuro-glial-vascular unit that works in concert to maintain the reproductive axis.Frontiers in Neuroendocrinology 07/2010; 31(3):241-58. · 11.43 Impact Factor
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ABSTRACT: Mammalian puberty requires complex interactions between glial and neuronal regulatory systems within the hypothalamus that results in the timely increase in the secretion of luteinizing hormone releasing hormone (LHRH). Assessing the molecules required for the development of coordinated communication networks between glia and LHRH neuron terminals in the basal hypothalamus, as well as identifying substances capable of affecting cell-cell communication are important. One such pathway involves growth factors of the epidermal growth factor (EGF) family that bind to specific erbB receptors. Activation of this receptor results in the release of prostaglandin-E(2) (PGE(2)) from adjacent glial cells, which then acts on the nearby LHRH nerve terminals to elicit release of the peptide. Another pathway involves novel genes which synthesize adhesion/signaling proteins responsible for the structural integrity of bi-directional glial-neuronal communication. In this review, we will discuss the influence of these glial-neuronal communication pathways on the prepubertal LHRH secretory system, and furthermore, discuss the actions and interactions of alcohol on these two signaling processes.International Journal of Environmental Research and Public Health 07/2011; 8(7):2876-94. · 1.61 Impact Factor