SummaryBackgroundOne of the global targets for non-communicable diseases is to halt, by 2025, the rise in the age-standardised adult prevalence of diabetes at its 2010 levels. We aimed to estimate worldwide trends in diabetes, how likely it is for countries to achieve the global target, and how changes in prevalence, together with population growth and ageing, are affecting the number of adults with diabetes.MethodsWe pooled data from population-based studies that had collected data on diabetes through measurement of its biomarkers. We used a Bayesian hierarchical model to estimate trends in diabetes prevalence—defined as fasting plasma glucose of 7·0 mmol/L or higher, or history of diagnosis with diabetes, or use of insulin or oral hypoglycaemic drugs—in 200 countries and territories in 21 regions, by sex and from 1980 to 2014. We also calculated the posterior probability of meeting the global diabetes target if post-2000 trends continue.FindingsWe used data from 751 studies including 4 372 000 adults from 146 of the 200 countries we make estimates for. Global age-standardised diabetes prevalence increased from 4·3% (95% credible interval 2·4–7·0) in 1980 to 9·0% (7·2–11·1) in 2014 in men, and from 5·0% (2·9–7·9) to 7·9% (6·4–9·7) in women. The number of adults with diabetes in the world increased from 108 million in 1980 to 422 million in 2014 (28·5% due to the rise in prevalence, 39·7% due to population growth and ageing, and 31·8% due to interaction of these two factors). Age-standardised adult diabetes prevalence in 2014 was lowest in northwestern Europe, and highest in Polynesia and Micronesia, at nearly 25%, followed by Melanesia and the Middle East and north Africa. Between 1980 and 2014 there was little change in age-standardised diabetes prevalence in adult women in continental western Europe, although crude prevalence rose because of ageing of the population. By contrast, age-standardised adult prevalence rose by 15 percentage points in men and women in Polynesia and Micronesia. In 2014, American Samoa had the highest national prevalence of diabetes (>30% in both sexes), with age-standardised adult prevalence also higher than 25% in some other islands in Polynesia and Micronesia. If post-2000 trends continue, the probability of meeting the global target of halting the rise in the prevalence of diabetes by 2025 at the 2010 level worldwide is lower than 1% for men and is 1% for women. Only nine countries for men and 29 countries for women, mostly in western Europe, have a 50% or higher probability of meeting the global target.InterpretationSince 1980, age-standardised diabetes prevalence in adults has increased, or at best remained unchanged, in every country. Together with population growth and ageing, this rise has led to a near quadrupling of the number of adults with diabetes worldwide. The burden of diabetes, both in terms of prevalence and number of adults affected, has increased faster in low-income and middle-income countries than in high-income countries.FundingWellcome Trust.

Leptin, the product of the ob gene, has emerged recently as a pivotal signal in the regulation of fertility. Although the actions of leptin in the control of reproductive function are thought to be exerted mainly at the hypothalamic level, the potential direct effects of leptin at the pituitary and gonadal level have been poorly characterised. In the present study, we first assessed the ability of leptin to regulate testicular testosterone secretion in vitro. Secondly, we aimed to evaluate whether leptin can modulate basal gonadotrophin and prolactin (PRL) release by incubated hemi-pituitaries from fasted male rats. To attain the first goal, testicular slices from prepubertal and adult rats were incubated with increasing concentrations (10 9 -10 7 M) of recombinant leptin. Assuming that in vitro testicular responsiveness to leptin may be dependent on the background leptin levels, testicular tissue from both fooddeprived and normally-fed animals was used. Furthermore, leptin modulation of stimulated testosterone secretion was evaluated by incubation of testicular samples with different doses of leptin in the presence of 10 IU human chorionic gonadotrophin (hCG). In addition, analysis of leptin actions on pituitary function was carried out using hemi-pituitaries from fasted adult male rats incubated in the presence of increasing concentrations (10 9 -10 7 M) of recombinant leptin. Serum testosterone levels, and basal and hCG-stimulated testosterone secretion by incubated testicular tissue were significantly decreased by fasting in prepubertal and adult male rats. However, a significant reduction in circulating LH levels was only evident in adult fasted rats. Doses of 10 9 -10 7 M leptin had no effect on basal or hCGstimulated testosterone secretion by testes from prepubertal rats, regardless of the nutritional state of the donor animal. In contrast, leptin significantly decreased basal and hCG-induced testosterone secretion by testes from fasted and fed adult rats. In addition, 10 9 M leptin inhibited LH and FSH secretion by incubated hemi-pituitaries from fasted adult males, whereas, at all doses tested, it was ineffective in modulating PRL release. Our results show that leptin, depending on the state of sexual maturation, is able to inhibit testosterone secretion acting at the testicular level. Furthermore, the present data suggest that the actions of leptin on the reproductive system are complex and are probably carried out at different levels of the hypothalamic-pituitary-gonadal axis.

Kisspeptins, products of the KiSS-1 gene with ability to bind G protein-coupled receptor 54 (GPR54), have been recently identified as major gatekeepers of reproductive function with ability to potently activate the GnRH/LH axis. Yet, despite the diversity of functional states of the female gonadotropic axis, pharmacological characterization of this effect has been mostly conducted in pubertal animals or adult male rodents, whereas similar studies have not been thoroughly conducted in the adult female. In this work, we evaluated maximal LH and FSH secretory responses to kisspeptin-10, as well as changes in sensitivity and hypothalamic expression of KiSS-1 and GPR54 genes, in different physiological and experimental models in the adult female rat. Kisspeptin-10 (1 nmol, intracerebroventricular) was able to elicit robust LH bursts at all phases of the estrous cycle, with maximal responses at estrus; yet, in diestrus LH, responses to kisspeptin were detected at doses as low as 0.1 pmol. In contrast, high doses of kisspeptin only stimulated FSH secretion at diestrus. Removal of ovarian sex steroids did not blunt the ability of kisspeptin to further elicit stimulated LH and FSH secretion, but restoration of maximal responses required replacement with estradiol and progesterone. Finally, despite suppressed basal levels, LH and FSH secretory responses to kisspeptin were preserved in pregnant and lactating females, although the magnitude of LH bursts and the sensitivity to kisspeptin were much higher in pregnant dams. Interestingly, hypothalamic KiSS-1 gene expression significantly increased during pregnancy, whereas GPR54 mRNA levels remained unaltered. In summary, our current data document for the first time the changes in hypothalamic expression of KiSS-1 system and the gonadotropic effects (maximal responses and sensitivity) of kisspeptin in different functional states of the female reproductive axis. The present data may pose interesting implications in light of the potential therapeutic use of kisspeptin analogs in the pharmacological manipulation of the gonadotropic axis in the female.

Ghrelin is a growth hormone-releasing acylated peptide from stomach. The purified peptide consist of 28 amino acids in which the serine 3 residue is n-octanoylated. Ghrelin has been reported to increase in vitro GH secretion as well as in vivo plasma GH levels in pentobarbital anaesthetized rats. The aim of this work was to characterize the stimulatory effect of Ghrelin on in vivo GH secretion in freely-moving rats. Furthermore, we compare the effect of Ghrelin with GHRH.In addition to vehicle, we administered different doses of Ghrelin (3 nmol/Kg, 12 nmol/Kg and 60 nmol/Kg); GHRH (3 nmol/Kg and 12 nmol/kg). Plasma GH levels were measured in blood samples taken at 5, 10, 15, 20, 30 and 45 min after their administration as an i.v. bolus at 0 min.Administration of Ghrelin led to an increase in plasma GH levels at all time-points tested (5, 10, 15, 20 and 30 min, P , 0X01; and 45 min, P , 0X05 in comparison to control untreated rats. A maximal stimulatory effect on plasma GH was observed following administration of 12 nmol/Kg of Ghrelin, the effect being similar to the one obtained with 60 nmol/Kg in terms of both AUC and mean peak GH levels. At the dose of 3 nmol/Kg GHRH and Ghrelin exhibited a similar stimulatory effect in term of both, AUC and mean peak GH levels. However following administration of a dose of 12 nmol/ Kg, the effect of Ghrelin was much greater than the same dose of GHRH in terms of both AUC and mean peak GH levels.In summary, this study provides the first evidences that Ghrelin exert a marked stimulatory effect in plasma GH levels in freely-moving rats and provides further evidences that Ghrelin may play an important role in the physiological control of GH secretion.

Ghrelin, a recently isolated hormone, seems to participate in the physiological regulation of GH secretion. Exogenously administered ghrelin stimulates GH discharge in all species so far tested including man, but whether this action is exerted at pituitary or alternatively at hypothalamic level is not known at present. To understand the point of ghrelin action a group of patients with organic lesion mainly in the hypothalamic area and matched controls were studied. Patients showed a severe GH deficiency after hypothalamic stimulation (ITT), but partial response after GHRH administration. Cases and controls were tested on three separate days by either ghrelin; GHRH; and ghrelin plus GHRH; always at 1 micro g/Kg iv. The mean GH peak after stimulation in the patients were: 0.4 +/- 0.1 micro g/L by ITT; 3.1 +/- 0.5 micro g/L after GHRH; 2.0 +/- 0.8 micro g/L after ghrelin; and 9.6 +/- 2.9 micro g/L after the combination of GHRH plus ghrelin. In the controls GHRH induced a GH peak of 21.2 +/- 7.5 micro g/L, and 75.1 +/- 16.0 micro g/L after ghrelin with a peak after GHRH + ghrelin of 103.5 +/- 26.4 micro g/L. These data indicate that when hypothalamic structures are not operative ghrelin, either alone or in combination with GHRH, is not able to significantly release GH. In addition to postulating a hypothalamic point of action for the ghrelin-induced GH secretion, these results suggests that ghrelin will not have significant clinical utility in patients with GH deficiency due to organic lesion.

The ability of kisspeptins, ligands of the G protein-coupled receptor 54, to potently elicit LH secretion is now undisputed. Yet, most of the pharmacological characterization of their gonadotropin-releasing effects has been conducted after intracerebral administration. In contrast, the effects of peripheral injection of kisspeptin remains less well defined. In this study, dynamic LH secretory responses to iv administration of kisspeptin-10 in different experimental settings are presented, and compared with those evoked by kisspeptin-52, using a protocol of serial blood sampling in conscious, freely moving male rats. LH responsiveness to peripheral administration of kisspeptin appeared extremely sensitive, as doses as low as 0.3 nmol/kg (0.1 microg/rat) evoked robust LH bursts, the magnitude of which was dose-dependent and apparently maximal in response to 3.0 and 30 nmol/kg kisspeptin-10. The ability of kisspeptin-10 to stimulate LH release was fully preserved, and even doubled in terms of relative increases, after short-term fasting despite suppression of prevailing LH levels. Repeated injections of kisspeptin-10 (four boluses, at 75-min intervals) evoked associated LH secretory pulses, the magnitude of which remained constant along the study period. Moreover, in this setting, in vivo LH responses to a terminal injection of GnRH were preserved, whereas basal and depolarization-induced GnRH release ex vivo was significantly enhanced. Finally, iv administration of kisspeptin-52 elicited dynamic LH responses analogous to that of kisspeptin-10; yet, their net magnitude and duration was slightly greater. In summary, we present in this study a series of experiments on the effects of systemic (iv) injection of single or repeated doses of kisspeptin upon dynamic LH secretion in conscious male rats. Aside from potential physiologic relevance, our present data might contribute to setting the basis for the rational therapeutic use of kisspeptin analogs in the pharmacological manipulation of the gonadotropic axis.

In neonates both nutrients and regulatory factors are transferred from the mother to the suckling infant via milk. In the present work, it has been shown that human milk contains immunoreactive leptin which is identical to intact human leptin by criteria of charge, size, immunorecognition and SDS-PAGE mobility. In experimental animals it was demonstrated that leptin is transferred from the circulation to mothers' milk, then to the infant's stomach and afterwards to infant blood. Maternal leptin in milk may play a regulatory role in the suckling infant.

The aim of this study was to investigate the regulation of serum leptin levels by gender and gonadal steroid milieu. Thus, we measured serum leptin levels by radioimmunoassay in (a) intact male and female rats, (b) female rats at different stages of the estrous cycle and (c) ovariectomized or orchidectomized rats. Gonadectomized groups were or were not implanted with silastic capsules (10 or 30 mm in length, 1.519 mm internal diameter; 3.06 mm external diameter) containing estradiol or testosterone and decapitated two weeks later.We found (i) intact female rats weighing 50 g, 250 g and 300 g exhibited higher serum leptin concentrations than intact male rats of similar body weight; (ii) leptin concentrations were not affected by the phase of the estrous cycle; (iii) two weeks after gonadectomy serum leptin concentrations increased in both male (from 4.47 Ϯ 1.87 to 8.76 Ϯ 1.24 ng/ml) and female (from 1.97 Ϯ 0.46 to 5.29 Ϯ 0.51 ng/ml) rats. The ovariectomy-induced increase in serum leptin levels was not dependent, at least completely, on changes in body weight since it could be observed when comparisons were made between ovariectomized rats and intact rats in estrus matched for body weight. In contrast the effect of orchidectomy on serum leptin levels appears to be dependent on changes in body weight since it was no longer observed when comparisons were made with a group of intact male rats matched for body weight.In conclusion, these results suggest that serum leptin concentrations are controlled by gonadal function either directly or as a consequence of changes in body weight.