Endocrine Abstracts

Skeletal muscle constitutes the largest endocrine organ in human body through capability of secreting myokines, which biological activity plays a key role in energy homeostasis. Among the myokines irisin (Ir) is of particular interest, considering it’s broad spectrum of protective influence on obesity and metabolic diseases development, determining therapeutical potential of this molecule. Latest studies indicate close interrelations between Ir and myostatin (Mstn), myokine that plays a principal role in muscle mass regulation. Acromegaly is a rare disease characterised by uncontrolled GH overexpression, what makes it an attractive, naturally occurring, research model for the studies of GH action. In this work GH relations with Ir and Mstn circulating levels were evaluated. The studied population consisted of 43 acromegalic patients and 39 healthy controls. Ir, Mstn, GH and IGF-1 serum concentrations were measured. Body composition was determined using dual-energy X-ray absorptiometry (DXA). Following glucose and lipid homeostasis parameters were evaluated: fasting glucose and insulin, HOMA-IR, HOMA-β, total cholesterol, LDL cholesterol, HDL cholesterol, triglicerides, atherogenic factors (Castelli I, Castelli II, AC, AIP, TG/HDL). The study group was divided into subgroups based on disease activity as well as lipid and glucose metabolism abnormalities. The results revealed decrease in Ir serum concertation in acromegaly (P = 0.02 vs controls) What’s more, Ir levels were negatively correlated with HOMA-IR (r = −0.51, P = 0,01), fasting insulin (r = −0.43, P = 0.01), were relatively lower in acromegalic patients with insulin resistance (IR+) (P = 0.04 vs IR^-) and negatively correlated with atherogenic factors. GH was negatively correlated with Mstn. Our findings indicate impaired endocrine function of skeletal muscle in the stetting of chronic GH overexpression, possible role of Ir alterations in the development of glucose abnormalities as well as relation with cardiovalcular risk in acromegaly. Additionally the role of GH in a regulation of Mstn was revealed.