Modulation of growth hormone and prolactin secretion in Trypanosoma cruzi-infected mammosomatotrophic cells.

OBJECTIVE

In a previous study, we reported an imbalance in the hypothalamus-pituitary-adrenal axis of mice acutely infected with the protozoan parasite Trypanosoma cruzi, the causative agent of Chagas disease.

METHODS

Possible effects of this parasitic infection on the endocrine function of other pituitary cell types were studied, in particular regarding the production of prolactin (PRL) and growth hormone (GH).

RESULTS

In the mammosomatotrophic cell line GH3, both GH and PRL secretion were decreased, reflecting the diminished PRL concentrations in the pituitary glands of infected mice. Additionally, expression of extracellular matrix proteins, e.g. laminin, was increased in T. cruzi-infected GH3 cells, which may be related to the diminished secretory function of these cells. Lastly, the expression of Pit-1, a major transcription factor for the PRL and GH genes, is also decreased in T. cruzi-infected cultures.

CONCLUSION

T. cruzi infection downregulates PRL and GH production. Combined with our previous data showing increased glucocorticoid levels following T. cruzi infection, the immunosuppression induced by T. cruzi infection may be partially related to multiple endocrine changes involving the hypothalamus-pituitary axis and corresponding target endocrine glands.