MYCOPLASMA-FERMENTANS ACTIVATES THE HYPOTHALAMOPITUITARY-ADRENAL AXISIN THE RAT

INTRACEREBROVENTRICULAR administration in rats of heat inactivated Myc oplasma fermentans caused a dose-and time-dependent increase in serum adrenocorticotrophin (ACTH) and corticosterone (CS). In rats with comp lete deafferentation of the mediobasal hypothalamus, which markedly de pleted the median eminence CRF-41, the ACTH and CS responses to M. fer mentans were completely inhibited. Pretreatment with dexamethasone abo lished the adrenocortical response to M. fermentans. In lipopolysaccha ride (LPS) unresponsive C3H/HeJ mice LPS failed to induce the adrenoco rtical response while administration of M. fermentans elicited a norma l CS response. These results suggest that: M. fermentans can activate the hypothalamo-pituitary-adrenal axis via a central mechanism which i nvolves hypothalamic ACTH secretagogue(s), and this effect is sensitiv e to the negative feedback of glucocorticoids. It is possible that the elevated glucocorticoid levels resulting from mycoplasma infection ma y be involved in the pathogenesis of mycoplasma-associated diseases.