PYRIDOSTIGMINE EFFECTS ON TSH RESPONSE TO TRH IN ADULT AND CHILDREN OBESE SUBJECTS

Thyrotropin releasing hormone (TRH) administration is known to induce a greater TSH response in normal subjects than in obese subjects. In o besity even GH and PRL response to various stimuli are blunted, presum ably because of an augmented somatostatinergic tone in obese subjects. Further studies have shown that pyridostigmine (Pyr), an acetylcholin esterase inhibitor, is capable of augmenting GH in obesity by means of somatostatin inhibition. In order to evaluate the possible interferen ce of an increased somatostatinergic tone on TSH secretion, we studied the TSH response to a TRH bolus in 5 obese children with or without a pyr pretreatment. Similarly, we tested a group of 10 obese adult subj ects, with TRH alone or TRH plus pyr administration, 30 min or 60 min before TRH. All subjects had a body weight of 30-50% greater than I.B. W. Our data show that a pretreatment with pyr, 60 min before TRH admin istration, significantly augments the TSH response in adult obese subj ects but not in children; the modality of pyr administration seems to be crucial to evidenciate such an alteration since the pyr pretreatmen t is not effective when administered 30 min before TRH. The absence of this pyr effect in obese children induces to hypothesize that somatos tatinergic tone is differentially modulated in children vs adult obese subjects.