Neuroendocrine system and mental function in sedentary and endurance-trained elderly males

Hypothalamic-pituitary-adrenal (HPAA) and -gonadal (HPGA) axis modification and cognitive impairments have been reported in elderly subjects and relat ed to physical training status. The aim of this study was to investigate if HPAA and HPGA regulation are altered in elderly distance runners (RUN: n = 8; age: 68.9 +/- 4.2 yrs; training: 65 +/- 20 km/wk over the last 20 yrs; means +/- SD) or are affected in elderly sedentary individuals (SED; n = 11 ; age: 69.1 +/- 2.6 yrs) by an aerobic training over 20 weeks (3 times/week , 30-60 min walking), respectively. The protocol included assessment of the hormone profile in basal non-suppressed state as well as evaluation of hor monal responses to dexamethasone (DEX, 1.5 mg) induced adrenal suppression, to post-DEX combined corticotrophin releasing hormone (CRH; 0.7 mu g/kg) a nd luteinizing hormone releasing hormone (LHRH, 0.7 mu g/kg) stimulation an d to exercise challenge (30 min cycle ergometry at 65% (V) over dot O(2)max ). Mental functions influenced by HPAA and HPGA activity were also assessed in RUN and SED before (SED-PRE) and after (SED-POST) the training program. Basal and post-DEX plasma concentrations of adrenocorticotropic hormone (A CTH), cortisol (CSL), luteinizing hormone (LH), follicle stimulating hormon e (FSH) and testosterone (T) did not differ between RUN and SED-PRE. nasal plasma free T concentration was significantly lower in RUN (RUN: 10.23 +/- 2.41 pg . ml(-1) vs. SED-PRE: 16.6 +/- 5.59 pg . ml(-1)). During releasing hormone challenge test after DEX administration (DEX/RH), no differences we re found between RUN and SED-PRE in plasma ACTH, LH, FSH and T response. Du ring this stimulation test, plasma CSL was significantly higher in RUN than in SED-PRE after 90 min (RUN: 5.86 +/- 3.65 mu g . dl(-1) vs. SED-PRE: 2.7 4 +/- 2.09 mu g . dl(-1)). afferences in plasma CSL concentrations between groups were not induced by 30-min exercise challenge. nasal hormone profile was not altered by training in SED. During DEX/RH only plasma ACTH concent ration was significantly higher in SED-POST compared to SED-PRE. Long and s hort-term memory function did not differ between RUN, SED-PRE and SED-POST. Our data suggest that following post-DEX CRH/LHRH challenge elderly endura nce athletes reveal-in the absence of altered peak values-a pattern of prol onged secretion of glucocorticoids. However, the high interindividual varia bility of plasma ACTH and CSL concentrations shows that reduced corticotrop ic sensitivity to negative feedback is not always induced by chronic exerci se stress. Lower plasma free T concentrations in RUN compared to SED are no t caused by modified LH synthesis-secretion capacity.