MISURAZIONE DIRETTA DEL TRAFFICO NERVOSO SIMPATICO IN DIFFERENTI FASI DELL'ACROMEGALIA
Creators: name: CARZANIGA, CHIARA
Publisher: name: Universit� degli Studi di Milano
Year: 2014

description: Sympathovagal imbalance has been shown in acromegaly by indirect measurements of adrenergic tone. Data regarding direct measurement of sympathetic activity are lacking as yet. 
Aim of this study was to assess the adrenergic tone through direct recording of muscle sympathetic nerve activity (MSNA) in acromegalic patients. Skin sympathetic nerve traffic (SSNA) was also recordered.
Study: After evaluating anthropometric and echocardiographic parameters, anterior pituitary function, glucose and lipid metabolism, and measuring plasma leptin, direct recording of sympathetic outflow via the microneurographic technique was performed in the following groups of subjects: 15 newly diagnosed acromegalics without hyperprolactinaemia, pituitary hormone deficiencies, obstructive sleep apnoea and cardiac hypertrophy (GROUP 1); 22 patients on somatostatin analogues (SSA), 11 of whom attaining biochemical control according to the currently accepted criteria and 11 not attaining biochemical control (GROUP 3); 2 acromegalic patients affected by OSAS (GROUP 4); 10 patients cured from acromegaly after neurosurgery (GROUP 5). The 15 newly diagnosed acromegalic patients were also studied for SSNA (GROUP 2). Fiften normalweight healthy subjects serving as controls. 
Results For similar anthropometric and metabolic parameters in patients and contros the group 1 displayed insulin resistance and a marked sympathetic inhibition (MSNA 18?3 � 8?10) vs controls (37?3 � 6?48 bursts/ min). A significant reduction in plasma leptin (1?6 � 1?04 vs 6?5 � 2?01 lg/l, P &lt; 0?0001) was also recorded in patients. Patients on SSA (GROUP 3), either with controlled or uncontrolled disease, displayed mean MSNA values (27.4 � 8.24 and 31.6 � 3.27 bursts/min, respectively) significantly lower than those shown by controls (p &lt; 0.01) but significantly higher than those found in untreated acromegalics (p &lt; 0.05). Mean MSNA values were not significantly different between controlled and uncontrolled SSA-treated patients. GROUP 5 showed mean MSNA values (30.17 � 3.2 bursts/min) significantly higher than those shown by GROUP 1 (p&lt; 0.01) and than patients non controlled by SSA (p&lt;0.05), but superimposable to that of patients controlled by SSA and controls. Mean leptin levels of cured were significantly higher than those shown by active patients (p&lt;0.01). MSNA levels registered in two patients affected by OSAS (GROUP 4) was higher than those found in acromegalic patients without OSAS. There were no significant
differences in SSNA between GROUP 2 and controls. Considering the whole population IGF-1 levels were negative correlated with MSNA and leptin levels ( p&lt;0.05 and p&lt;0.0005, respectively) and MSNA was positive correlated with leptin levels (p&lt;0.05).
Comment. Our study demonstrates that recently diagnosed acromegalic patients, in spite of insulin resistance (a condition known to increase MSNA), display a decreased sympathetic outflow. This finding, together with the tendency to normalization of adrenergic tone in pharmacologically treated and cured acromegalic patients and the negative correlations found between IGF-1 on the one hand and leptin and MSNA on the other hand, and the positive correlation between leptin and MSNA, suggests a relevant influence of the GH/IGF-I axis on the activity of the sympathetic nervous system through leptin modification.