The sweating apparatus in growth hormone deficiency, following treatment with r-hGH and in acromegaly

Adult growth hormone deficient patients are known to exhibit reduced sweati ng and their ability to thermoregulate is diminished. Treatment of these pa tients with recombinant human growth hormone (r-hGH) is claimed to reverse these abnormalities. We have investigated this claim, as well as the mechan ism underlying these altered sweating responses in GH-deficient patients as part of a placebo-controlled study on the effects of 6-12 months r-hGH the rapy. Skin biopsies were obtained from these subjects and changes in morpho logy and innervation parameters for the eccrine sweat glands were examined. These included histochemistry for acetylcholinesterase (AChE) and immunohi stochemistry for the neuropeptide vasoactive intestinal polypeptide (VIP) a nd for PGP9.5, a general neuronal marker. Sweat gland acinar size and peria cinar innervation were measured by computerised image analysis. The patient s underwent pilocarpine iontophoresis sweat rate tests and their serum insu lin-like growth factor 1 (IGF 1) levels were assessed. Since active acromeg aly involves excess GH secretion and hyperhidrosis, skin biopsies and sweat tests were also carried out on a group of these patients, as well as on co ntrol subjects. We have demonstrated a sweating defect in adult GH-deficiency which is acco mpanied by a reduction in AChE and VIP Levels in the nerve supply to sweat glands. Following r-hGH therapy, an increase in AChE and VIP staining is se en in the sudomotor nerves accompanied by restoration of sweat rates and se rum IGF-1 levels. Hence, normalization of sweat gland function includes rec overy of sudomotor synapse constituents. A trophic effect of GH on sweat gl and epithelium and/or on the associated nerves is proposed, supported by th e observation that in acromegaly the size of sweat gland acini and the dens ity of innervation to the sweat glands was greater than in controls. (C) 20 01 Published by Elsevier Science B.V.