Adipokinetic hormone signaling determines dietary fatty acid preference through maintenance of hemolymph fatty acid composition in the cricket Gryllus bimaculatus.

Adipokinetic hormone (AKH), an analog of mammalian glucagon, functions in supplying the required energy by releasing lipids and carbohydrates from the fat body into the hemolymph. Our previous study showed that AKH receptor (AKHR) knockdown in the two-spotted cricket Gryllus bimaculatus decreased hemolymph lipid levels and increased its feeding frequency. To reveal underlying mechanisms by which AKH signaling modulates lipid homeostasis, we analyzed the fatty acid composition as the lipid structure in the crickets. AKH administration significantly increased the proportion of unsaturated fatty acids (USFAs) to total fatty acids with decrease of the saturated fatty acids (SFAs) in hemolymph, while these proportions were inversely changed in RNA interference-mediated AKHR-knockdowned (AKHRRNAi) crickets. Interestingly, knockdown of hormone-sensitive lipase (Hsl) by RNAi (HslRNAi) affected the proportion of USFAs and SFAs in a similar manner to that observed in AKHRRNAi crickets. AKH administration in HslRNAi crickets did not change hemolymph fatty acid composition, indicating that AKH signaling critically altered fatty acid composition in the hemolymph through Hsl. In addition, a choice assay revealed that AKHRRNAi significantly increases the preference of USFAs. These data indicate that hemolymph lipid level and composition were modulated by AKH signaling with a complementary feeding behavior toward USFAs.

Newly identified allatostatin Bs and their receptor in the two-spotted cricket, Gryllus bimaculatus.

A cDNA encoding allatostatin Bs (ASTBs) containing the W(X)6W motif was identified using a database generated by a next generation sequencer (NGS) in the two-spotted cricket, Gryllus bimaculatus. The contig sequence revealed the presence of five novel putative ASTBs (GbASTBs) in addition to GbASTBs previously identified in G. bimaculatus. MALDI-TOF MS analyses revealed the presence of these novel and previously identified GbASTBs with three missing GbASTBs. We also identified a cDNA encoding G. bimaculatus GbASTB receptor (GbASTBR) in the NGS data. Phylogenetic analysis demonstrated that this receptor was highly conserved with other insect ASTBRs, including the sex peptide receptor of Drosophila melanogaster. Calcium imaging analyses indicated that the GbASTBR heterologously expressed in HEK293 cells exhibited responses to all identified GbASTBs at a concentration range of 10(-10)-10(-5)M.

Dose determination of cinacalcet hydrochloride in Japanese hemodialysis patients with secondary hyperparathyroidism.

Cinacalcet hydrochloride is a calcimimetic agent that activates the calcium-sensing receptor on the surface of parathyroid cells and inhibits parathyroid hormone (PTH) secretion. To manage secondary hyperparathyroidism, cinacalcet, which lowers PTH levels without increasing serum calcium, phosphorus and calcium-phosphorus product (Ca x P) levels, may provide a new potential therapy. To identify the optimal starting dose of cinacalcet for Japanese hemodialysis patients with secondary hyperparathyroidism, this double-blind, placebo-controlled, parallel, dose-finding study was conducted. One hundred and twenty Japanese hemodialysis patients with intact PTH levels greater than or equal to 300 pg/mL were randomized into four groups: placebo, and 12.5, 25 and 50 mg of cinacalcet. The treatment period was three weeks followed by a two-week follow-up observation period. Cinacalcet decreased serum intact PTH levels in a dose-dependent manner, and also decreased serum calcium, phosphorus, Ca x P, tartrate-resistant acid phosphatase and osteocalcin levels. The treatment with cinacalcet was generally well tolerated in this study. However, the incidence of treatment-related adverse events, such as gastrointestinal disorders and hypocalcemia, and the rate of withdrawal from the study due to treatment-related adverse events were higher in the 50 mg dose group than in the other groups. On the basis of both efficacy and safety results, 25 mg has been identified as the optimal starting dose of cinacalcet for Japanese hemodialysis patients with secondary hyperparathyroidism.

Cinacalcet (KRN1493) effectively decreases the serum intact PTH level with favorable control of the serum phosphorus and calcium levels in Japanese dialysis patients.

BACKGROUND: Cinacalcet hydrochloride (KRN1493) acts on the parathyroid calcium receptors to suppress parathyroid hormone (PTH) secretion, and is already in wide use in the United States and the European countries. In this study, we examined the efficacy and safety of cinacalcet in Japanese patients on maintenance haemodialysis. METHODS: One hundred forty-four patients with serum intact PTH (iPTH) levels >or=300 pg/ml were enrolled and randomly allocated to two groups assigned to receive either cinacalcet or placebo for 14 weeks. Cinacalcet was started at the dose of 25 mg/day and titrated up to 100 mg/day to achieve the target iPTH level of <250 pg/ml. RESULTS: Cinacalcet significantly decreased the median iPTH level from 606.5 pg/ml to 241.0 pg/ml, despite the mean dialysis vintage being 2.4 times longer (14.3+/-7.1 years) and the proportion of patients receiving vitamin D sterols being higher, than in the phase 3 studies conducted in the US/EU. The target iPTH level was achieved in 51.4% of the patients in the cinacalcet group, in sharp contrast to only 2.8% in the placebo group. Furthermore, the percentage of patients with both the serum calcium and phosphorus levels within the target range in the K/DOQI guidelines increased from 4.2% to 26.4% by cinacalcet. CONCLUSIONS: These results suggest that lower dose levels of cinacalcet, as compared to those in US/EU studies, may be sufficient effectively suppress the serum iPTH levels and allow favourable management of the serum calcium and phosphorus levels in Japanese patients, having a longer average dialysis vintage.

[Vitamin D therapy in renal osteodystrophy].

In Japan, three oral preparations (calcitriol, alfacalcidol and falecalcitriol) and two intravenous preparations (calcitriol and maxacalcitol) are now available for the vitamin D(3) therapy in renal osteodystrophy. In general, oral therapy is indicated for mild cases of secondary hyperparathyroidism (intact PTH<300 pg/mL) to maintain adequate level of serum PTH except "calcitriol oral pulse therapy" for moderate to severe cases. Recently, intravenous therapy has been introduced to treat more severe cases by using the advantage of rapid clearance of these metabolites. In order to use these preparations safely, adequate level of both serum intact PTH (150-300 pg/mL) and Ca/P product (<55) should be maintained to prevent from adynamic bone and vascular calcification.

Effect of treatment with oral calcitriol on calcium metabolism and fasting serum 25(OH)- or 1,25(OH)2-vitamin D level in Japanese postmenopausal women.

The aim of this study was to investigate the effect of daily oral administration of calcitriol on calcium metabolism in Japanese postmenopausal women. For this purpose, we administered 0.5 microg of daily calcitriol to 18 Japanese postmenopausal women for up to 24 weeks. During the first 28 days, daily administration of 0.5 microg of oral calcitriol increased fasting serum 1,25(OH) 2D levels significantly in 9 women (Group B) (p<0.005), while no significant change was seen in another 9 women without calcitriol administration (Group A). The first 28-day calcitriol supplement increased fasting urinary calcium excretion (urinary Ca/Cr) from 0.133 +/- 0.072 to 0.171 +/- 0.089 (p<0.05) and fractional excretion of calcium (FECa) without changing serum Ca2+. Urinary NTx/Cr excretion, an index of bone resorption, decreased significantly from 64.8 +/- 24.5 to 50.3 +/- 27.2 nMBCE/mMCr in Group B. Following the 28-day control period, 0.5 microg of oral calcitriol was also administered to women in Group A for another 20 weeks. At the end of the 24-week investigation period, the effects of oral calcitriol on urinary calcium excretion and bone resorption were still significant in both Group A and B. A positive correlation was found between urinary Ca/Cr and NTx/Cr excretion at the start (r = 0.657, p<0.05), but this correlation was lost by calcitriol treatment (r = 0.135). These results indicated that calcitriol supplement was effective in suppressing bone resorption in postmenopausal women, and that an increased fasting urinary calcium excretion due to calcitriol supplement was predominantly caused by increased intestinal calcium absorption in these women.