JMV2894, a novel growth hormone secretagogue, accelerates body mass recovery in an experimental model of cachexia.

Oncologic patients subjected to chemotherapy frequently present aphagia, malnutrition, and cachexia. The purpose of this study was to investigate whether selected growth hormone secretagogues including hexarelin, JMV2894 and JMV2951 could antagonize body weight loss and wasting induced by cisplatin administration in rats. The three growth hormone secretagogues behaved as full agonists of the growth hormone secretagogues receptor both in terms of ability to stimulate calcium mobilization in Chinese hamster ovary cells and stimulation of growth hormone release in neonatal rats. Adult rats were (i) treated with vehicle throughout (controls), or (ii) treated with cisplatin (days 1-3) and a growth hormone secretagogues or vehicle, (days 1-12). Body weight and food consumption were measured daily. Although all growth hormone secretagogues caused initial transient acute increases in food intake, the total amount of food eaten by controls and growth hormone secretagogues treated groups over the 12 experimental days was not significantly different. All groups pre-treated with cisplatin lost up to 5-10 % body weight in the first 4 days; they subsequently gained weight at a rate comparable with controls. Interestingly, rats which received JMV2894 demonstrated a faster gain in body weight than any other growth hormone secretagogues treated group and at the end of the protocol reached a weight similar to that of controls. JMV2894 did not stimulate perirenal and epididymal fat accumulation but reduced MuRF mRNA levels in skeletal muscles. In conclusion, our findings demonstrate that JMV2894 antagonizes cisplatin induced weight loss in rats and may prove useful in antagonizing cachexia associated with cancer and chemotherapy in humans.

Novel domain-selective ACE-inhibiting activity of synthetic growth hormone secretagogues.

The mechanisms of cardiovascular protective effects of ghrelin and its synthetic analogs are still largely unknown. Our first aim was to ascertain whether or not natural and synthetic ligands of GHS-R1a are capable of interfering with the activity of the renin-angiotensin system. Second, since polymorphisms in the ACE gene have been associated with Alzheimer's dementia (AD) and ACE is potentially involved in brain ß-amyloid degradation, we also investigated the state of ghrelin axis and inflammatory markers in patients with AD and vascular dementia (VaD). Desacyl ghrelin, hexarelin, EP80317, and GHRP-6 all significantly inhibited ACE activity in vitro; by comparison, the efficacies of ghrelin and MK-0677 were significantly lower, suggesting that ACE-inhibiting activity is unrelated to ligand affinity to GHS-R1a. ACE was capable of cleaving Aßin vitro, reducing its ability to aggregate in fibrillar Aß. Interestingly, this protective effect of ACE was blunted by enalapril but not hexarelin or EP80317. Desacyl ghrelin levels were lower in VaD subjects compared with AD and control subjects, whereas ghrelin and TNF-α levels were similar in all groups. VaD subjects demonstrated greater levels of mRNA for GHS-R1a, PPAR-γ and CD36 in peripheral blood lymphocytes compared with other groups. In conclusion, some GHSs are effective ACE-inhibitors, and this activity may contribute to their cardiovascular effects. Hexarelin or EP80317 do not inhibit the N-domain of ACE, which is also involved in the metabolism of ß-amyloid, suggesting the possibility of developing new antihypertensive drugs with improved therapeutic potential.