Abstract
Exposure to sex steroids during the fetal and neonatal periods plays an important role in the organization of the hypothalamus. Since the rate of growth of the pubertal and adult animal is also affected by neonatal sex steroid exposure, we asked the question as to whether this phenomenon is due to an effect of these steroids on those hypothalamic neurons involved in stimulating GH, i.e., GHRH neurons. To address this question, the following experimental groups were studied:
Where M=male, F=female; Oil=injection with 100 μg oil; Tinj=injection with 250 μg T in 100 μg oil; Simp=empty Silastic capsule; Timp=Silastic capsule containing T. Growth was charted throughout development and was significantly affected by these treatments. Animals were sacrificed (day 75) and the brains removed and processed for in situ hybridization for GHRH mRNA. The total number of GHRH cells and the relative level oi GHRH mRNA (analyzed by an automaled image analysis system) were assessed in anatomically matched slides. Neonatal T had a significant effect on the number of detectable GHRH neurons in the hypothalamus (ANOVA: p<0.0001). Animals exposed to neonatal T had significantly more GHRH nautons than those that were not. Adult T-treatment did not affect the number of detectable GHRH neurons, but significantly influenced levels of GHRH mRNA (ANOVA: p<0.0001). Furthermore, adult T-treatement had a significantly greater effect in those animals that had received neonatal T when compared to those animals that did not receive neonatal T (2-way ANOVA: p<0.05). These results suggest that one way in which exposure to sex steroids during the neonatal period affects the growth axis is by increasing the number of hypothalamic GHRH neurons, as well as 10 modulate the ability of these neurons to respond to changes in circulating levels of testosterone.
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Chowen, J., González-Parra, S., Garcia-Segura, L. et al. NEONATAL TESTOSTERONE MODULATES THE NUMBER AND RESPONSIVITY OF GROWTH HORMONE-RELEASING HORMONE (GHRH) NEURONS. Pediatr Res 33 (Suppl 5), S28 (1993). https://doi.org/10.1203/00006450-199305001-00151
Issue Date:
DOI: https://doi.org/10.1203/00006450-199305001-00151