Decreased adrenergic tone in acromegaly: evidence from direct recording of muscle sympathetic nerve activity

Abstract

Newly diagnosed acromegalic patients without cardiac hypertrophy display a decreased sympathetic outflow in spite of insulin resistance. This finding might be related to hypoleptinaemia.

Impact of Successful Treatment of Acromegaly on Overnight Heart Rate Variability and Sleep Apnea

“…The increased sympathetic/decreased parasympathetic activity observed here in patients with active acromegaly could appear to be somewhat at variance with the decreased sympathetic outflow observed elsewhere in peripheral muscle (42). However, this latter study involved newly diagnosed acromegalic patients without cardiac hypertrophy, whereas three of the 16 patients of our study had moderate cardiac hypertrophy.…”

Differential patterns of regional neuroadrenergic cardiovascular drive in acromegalic disease

“…Confirming previous findings by our group based on the direct assessment of adrenergic neural drive via the microneurographic technique, the present study shows that MSNA is markedly reduced in the early stage of acromegaly characterized by the absence of target organ damage, hyperprolactinaemia and pituitary hormone deficiencies. Furthermore, we provide new findings that the reduction in MSNA is not paralleled by a concomitant reduction in SSNA, which was within the normal range in patients with acromegaly and not significantly different from the SSNA in the control group.…”

“…Respiration rate (RR) was monitored by a strain gauge pneumograph positioned at the mid‐chest level. Multiunit recording of efferent post‐ganglionic sympathetic nerve activity to skeletal muscle or the skin were obtained through a tungsten microelectrode inserted in the right or left peroneal nerve posterior to the fibular head, as described previously . Integrated nerve activity was monitored by a loudspeaker and displayed and recorded on a computer (LabChart6; ADInstruments, Dunedin, New Zealand), along with blood pressure, HR and RR.…”

“…the acromegalic state), in which: (i) the low‐frequency component of the power spectral analysis of the heart rate signal (i.e. an indirect marker of the adrenergic influences on the heart) has been shown to be reduced; 4 and (ii) a decrease in directly recorded muscle sympathetic nerve firing rate in the peroneal nerve has been reported . The sympathetic inhibition detected in acromegaly has also been documented indirectly by the finding that under conditions characterized by a deficiency in growth hormone release, such as in hypopituitary disease, sympathetic activity undergoes marked activation that is completely reversed by the replacement of normal growth hormone levels .…”

“…The sympathetic inhibition detected in acromegaly has also been documented indirectly by the finding that under conditions characterized by a deficiency in growth hormone release, such as in hypopituitary disease, sympathetic activity undergoes marked activation that is completely reversed by the replacement of normal growth hormone levels . It has also been shown that acromegaly is characterized by reduced levels of leptin in the circulation. It has been established that circulating leptin concentrations may act as a humoral signal contributing to adiposity‐associated increases in muscle sympathetic nerve activity MSNA in humans.…”