The Postnatal Leptin Surge Supports Immune Cell Function in Rats.

BACKGROUND: Leptin plays an important role in the regulation of the immune response. There is a physiological surge of leptin in rodents during the neonatal period, which has mainly been studied in the context of brain development. However, little is known about the effects of this neonatal leptin surge on immunity. Therefore, we investigated whether blocking this leptin surge could affect several immune functions. METHODS: Male and female rats were injected subcutaneously with 5 mg/Kg/day of rat pegylated super leptin antagonist during the neonatal period (PND5-9). On the peripubertal period, relevant functions as well as cytokine release by spleen leukocytes were studied in these animals. RESULTS: The results showed that the animals significantly display an impaired anti-tumor NK activity and chemotactic and proliferation capacity of lymphocytes in response to mitogens. In addition, several cytokine concentrations, released under mitogen-stimulated conditions, were also altered. CONCLUSION: In conclusion, the neonatal leptin surge seems to be involved in the establishment of an adequate immune response and cytokine profile, which are crucial for the maintenance of a healthy life.

Exercise-induced re-programming of age-related metabolic changes in microglia is accompanied by a reduction in senescent cells.

Microglial activation and neuroinflammatory changes are characteristic of the aged brain and contribute to age-related cognitive impairment. Exercise improves cognitive function in aged animals, perhaps because of a modulatory effect on microglial activation. Recent evidence indicates that inflammatory microglia are glycolytic, driven by an increase in 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3), an enzyme that is described as the master regulator of glycolysis. Here we investigated whether microglia from aged animals exhibited a glycolytic signature and whether exercise exerted a modulatory effect on this metabolic profile. Young (4 month-old) and aged (18 month-old) mice were trained for 10 days on a treadmill. One day before sacrifice, animals were assessed in the novel object recognition and the object displacement tests. Animals were sacrificed after the last bout of exercise, microglial cells were isolated, cultured for 5 days and assessed for metabolic profile. Performance in both behavioural tests was impaired in sedentary aged animals and exercise attenuated this age-related effect. A significant increase in glycolysis, glycolytic capacity and PFKFB3 was observed in microglia from aged animals and exercise ameliorated these effects, while it also increased the phagocytic capacity of cells. The senescent markers, ß-galactosidase and p16INK4A, were increased in microglia from sedentary aged mice, and expression of these markers was significantly decreased by exercise. The data demonstrate that the exercise-related improved cognition is orchestrated by a normalization of the metabolic profile and functionality of microglia.

Early maternal deprivation enhances voluntary alcohol intake induced by exposure to stressful events later in life.

In the present study, we aimed to assess the impact of early life stress, in the form of early maternal deprivation (MD, 24 h on postnatal day, pnd, 9), on voluntary alcohol intake in adolescent male and female Wistar rats. During adolescence, from pnd 28 to pnd 50, voluntary ethanol intake (20%, v/v) was investigated using the two-bottle free choice paradigm. To better understand the relationship between stress and alcohol consumption, voluntary alcohol intake was also evaluated following additional stressful events later in life, that is, a week of alcohol cessation and a week of alcohol cessation combined with exposure to restraint stress. Female animals consumed more alcohol than males only after a second episode of alcohol cessation combined with restraint stress. MD did not affect baseline voluntary alcohol intake but increased voluntary alcohol intake after stress exposure, indicating that MD may render animals more vulnerable to the effects of stress on alcohol intake. During adolescence, when animals had free access to alcohol, MD animals showed lower body weight gain but a higher growth rate than control animals. Moreover, the higher growth rate was accompanied by a decrease in food intake, suggesting an altered metabolic regulation in MD animals that may interact with alcohol intake.

Microglia isolation from aging mice for cell culture: A beginner's guide.

Microglia, the innate immune cell of the central nervous system, play significant roles in brain development, maintenance, homeostasis, and neuroinflammation. Although numerous methods have been developed to isolate microglia from embryonic or postnatal mouse brains, still major difficulties exist in isolating microglia from adult mice, often resulting in low yield and risk of cellular activation. Therefore, there is a need for a more efficient method to isolate pure and high-yield microglia from adult mice to study various neurodegenerative diseases. The aim of this study was to develop a fully functional protocol for the isolation of microglia by comparing different protocols. We investigated the efficacy of three protocols in terms of cell yield, purity, cellular activation, cellular aging, and migration properties and proposed the modified protocol (PROTOCOL 1), which provides an optimal yield of functional microglial cells with a minimum of material and equipment and allows young researchers with little experience to isolate microglia and helps them to delve deeper into the world of neuroscience.

Acute Stress, Induced by IFNγ + Aß, and Chronic Stress, Induced by Age, Affect Microglia in a Sex-Specific Manner.

Microglial phenotype changes in the aged brain, and also in neurodegenerative diseases, and it is generally accepted that these changes at least contribute to the inflammation that can have detrimental effects on brain health. Accumulating data have determined that there are multiple microglial activation states with consistent findings indicating that with stressors including age, a switch towards an inflammatory phenotype occurs. Among the changes that accompany this is a change in metabolism, whereby glycolysis is increased in microglia. Here, we asked whether sex impacted on the response of microglia to two stressors, interferon-γ + amyloid-ß (IFNγ + Aß) and age. The data show that IFNγ + Aß triggered cells from female mice to adopt a glycolytic phenotype. Metabolism was also altered with age; microglia from aged male mice responded by increasing oxidative phosphorylation, and microglial motility was preserved, contrasting with microglia from female mice where motility was compromised. We conclude that sex is a significant variable in the responses of microglia to stressors.

The Relationship between Depressive Symptoms, Quality of Life and miRNAs 8 Years after Bariatric Surgery.

(1) Background: There are conflicting results on whether weight loss after bariatric surgery (BS) might be associated with quality of life (QoL)/depressive symptomatology. We aim to determine whether BS outcomes are associated with QoL/depressive symptomatology in studied patients at the 8-year follow-up after BS, as well as their relationship with different serum proteins and miRNAs. (2) Methods: A total of 53 patients with class III obesity who underwent BS, and then classified into "good responders" and "non-responders" depending on the percentage of excess weight lost (%EWL) 8 years after BS (%EWL ≥ 50% and %EWL < 50%, respectively), were included. Basal serum miRNAs and different proteins were analysed, and patients completed tests to evaluate QoL/depressive symptomatology at 8 years after BS. (3) Results: The good responders group showed higher scores on SF-36 scales of physical functioning, role functioning-physical, role functioning-emotional, body pain and global general health compared with the non-responders. The expression of hsa-miR-101-3p, hsa-miR-15a-5p, hsa-miR-29c-3p, hsa-miR-144-3p and hsa-miR-19b-3p were lower in non-responders. Hsa-miR-19b-3p was the variable associated with the response to BS in a logistic regression model. (4) Conclusions: The mental health of patients after BS is limited by the success of the intervention. In addition, the expression of basal serum miRNAs related to depression/anxiety could predict the success of BS.

The Modulatory Effects of DMF on Microglia in Aged Mice Are Sex-Specific.

There is a striking sex-related difference in the prevalence of many neurodegenerative diseases, highlighting the need to consider whether treatments may exert sex-specific effects. A change in microglial activation state is a common feature of several neurodegenerative diseases and is considered to be a key factor in driving the inflammation that characterizes these conditions. Among the changes that have been described is a switch in microglial metabolism towards glycolysis which is associated with production of inflammatory mediators and reduced function. Marked sex-related differences in microglial number, phenotype and function have been described in late embryonic and early postnatal life in rodents and some reports suggest that sexual dimorphism extends into adulthood and age and, in models of Alzheimer's disease, the changes are more profound in microglia from female, compared with male, mice. Dimethyl fumarate (DMF) is a fumaric acid ester used in the treatment of psoriasis and relapsing remitting multiple sclerosis and, while its mechanism of action is unclear, it possesses anti-inflammatory and anti-oxidant properties and also impacts on cell metabolism. Here we treated 16-18-month-old female and male mice with DMF for 1 month and assessed its effect on microglia. The evidence indicates that it exerted sex-specific effects on microglial morphology and metabolism, reducing glycolysis only in microglia from female mice. The data suggest that this may result from its ability to inactivate glyceraldehyde-3-phosphate dehydrogenase (GAPDH).

Sex-Related Microglial Perturbation Is Related to Mitochondrial Changes in a Model of Alzheimer's Disease.

Many studies implicate microglia in the pathogenesis of Alzheimer's disease (AD) but precisely how these cells make their impact has not been determined to date. One contributory factor is likely to be the enhanced production of inflammatory mediators and it is now known that microglia with this secretory phenotype exhibit other adaptations including in their morphology, function, and metabolism. AD, like many neurological disorders, demonstrates a sex bias and recent evidence indicates that the sexual dimorphism in microglial function, which has been recognized for many years in early development, persists into adulthood and aging. Here, we demonstrate sex-related differences in microglia from post mortem tissue of male and female AD patients and a marked increase in the number of dystrophic and rod-shaped microglia in tissue from female AD patients compared with males. Furthermore, there was an increase in iron-laden microglia in tissue from female AD patients and this has been reported to reflect mitochondrial changes. To address this further, we assessed changes in microglia from male and female APP/PS1 mice and demonstrate that iron accumulation in microglia is increased to a greater extent in tissue prepared from females compared with males. This was associated with altered expression of genes coding for proteins that modulate mitochondrial function. The findings suggest that sex-related differences in the severity and perhaps incidence of AD may, at least in part, arise from sexual dimorphism in microglia.

Mitochondrial Homeostasis in Obesity-related Hypertriglyceridemia.

CONTEXT: The prevalence of obesity and hypertriglyceridemia is an alarming worldwide health issue. Mitochondria play a central role in these disorders as they control cell metabolism. OBJECTIVE: The aim of the present study was to characterize mitochondrial homeostasis in subcutaneous and visceral adipose tissue (SAT and VAT) in grade III obese patients with and without hypertriglyceridemia. Moreover, this study presents the evaluation of mitochondrial fitness as a marker for hypertriglyceridemia improvement. PATIENTS: Eight control and 12 hypertriglyceridemic (HTG) grade III obese subjects undergoing bariatric surgery were included. MAIN OUTCOME MEASURES: Anthropometric and biochemical data were obtained before and 3 months after surgery. Mitochondrial homeostasis was evaluated by mitochondrial DNA (mtDNA), gene expression and protein abundance in SAT and VAT. RESULTS: Mitophagy-related gene expression was increased in HTG SAT and VAT, while mitochondrial marker gene expression and mtDNA were decreased, indicating an altered mitochondrial homeostasis in HTG. Mitophagy protein abundance was increased in VAT of those subjects that did not improve their levels of triglycerides after bariatric surgery, whereas mitochondrial protein was decreased in the same tissue. Indeed, triglyceride levels positively correlated with mitophagy-related genes and negatively with mitochondrial content markers. Moreover, mitochondria content and mitophagy markers seem to be significant predictors of hypertriglyceridemia and hypertriglyceridemia remission. CONCLUSIONS: Mitochondrial homeostasis of adipose tissue is altered in hypertriglyceridemic patients. At the protein level, mitochondria content and mitophagy are potential markers of hypertriglyceridemia remission in obese patients after bariatric surgery. These results may contribute to the implementation of a clinical approach for personalized medicine.

EVOO Promotes a Less Atherogenic Profile Than Sunflower Oil in Smooth Muscle Cells Through the Extracellular Vesicles Secreted by Endothelial Cells.

Background: Little is known about the effect of extra virgin olive (EVOO) and sunflower oil (SO) on the composition of extracellular vesicles (EVs) secreted by endothelial cells and the effects of these EVs on smooth muscle cells (SMCs). These cells play an important role in the development of atherosclerosis. Methods: We evaluated the effects of endothelial cells-derived EVs incubated with triglyceride-rich lipoproteins obtained after a high-fat meal with EVOO (EVOO-EVs) and SO (SO-EVs), on the transcriptomic profile of SMCs. Results: We found 41 upregulated and 19 downregulated differentially expressed (DE)-miRNAs in EVOO-EVs. Afterwards, SMCs were incubated with EVOO-EVs and SO-EVs. SMCs incubated with SO-EVs showed a greater number of DE-mRNA involved in pathways related to cancer, focal adhesion, regulation of actin cytoskeleton, and MAPK, toll-like receptor, chemokine and Wnt signaling pathways than in SMCs incubated with EVOO-EVs. These DE-mRNAs were involved in biological processes related to the response to endogenous stimulus, cell motility, regulation of intracellular signal transduction and cell population proliferation. Conclusion: EVOO and SO can differently modify the miRNA composition of HUVEC-derived EVs. These EVs can regulate the SMCs transcriptomic profile, with SO-EVs promoting a profile more closely linked to the development of atherosclerosis than EVOO-EVs.

Microglial metabolism is a pivotal factor in sexual dimorphism in Alzheimer's disease.

Age and sex are major risk factors in Alzheimer's disease (AD) with a higher incidence of the disease in females. Neuroinflammation, which is a hallmark of AD, contributes to disease pathogenesis and is inexorably linked with inappropriate microglial activation and neurodegeneration. We investigated sex-related differences in microglia in APP/PS1 mice and in post-mortem tissue from AD patients. Changes in genes that are indicative of microglial activation were preferentially increased in cells from female APP/PS1 mice and cells from males and females were morphological, metabolically and functionally distinct. Microglia from female APP/PS1 mice were glycolytic and less phagocytic and associated with increased amyloidosis whereas microglia from males were amoeboid and this was also the case in post-mortem tissue from male AD patients, where plaque load was reduced. We propose that the sex-related differences in microglia are likely to explain, at least in part, the sexual dimorphism in AD.

Iron accumulation in microglia triggers a cascade of events that leads to altered metabolism and compromised function in APP/PS1 mice.

Among the changes that typify Alzheimer's disease (AD) are neuroinflammation and microglial activation, amyloid deposition perhaps resulting from compromised microglial function and iron accumulation. Data from Genome Wide Association Studies (GWAS) identified a number of gene variants that endow a significant risk of developing AD and several of these encode proteins expressed in microglia and proteins that are implicated in the immune response. This suggests that neuroinflammation and the accompanying microglial activation are likely to contribute to the pathogenesis of the disease. The trigger(s) leading to these changes remain to be identified. In this study, we set out to examine the link between the inflammatory, metabolic and iron-retentive signature of microglia in vitro and in transgenic mice that overexpress the amyloid precursor protein (APP) and presenilin 1 (PS1; APP/PS1 mice), a commonly used animal model of AD. Stimulation of cultured microglia with interferon (IFN)γ and amyloid-ß (Aß) induced an inflammatory phenotype and switched the metabolic profile and iron handling of microglia so that the cells became glycolytic and iron retentive, and the phagocytic and chemotactic function of the cells was reduced. Analysis of APP/PS1 mice by magnetic resonance imaging (MRI) revealed genotype-related hypointense areas in the hippocampus consistent with iron deposition, and immunohistochemical analysis indicated that the iron accumulated in microglia, particularly in microglia that decorated Aß deposits. Isolated microglia prepared from APP/PS1 mice were characterized by a switch to a glycolytic and iron-retentive phenotype and phagocytosis of Aß was reduced in these cells. This evidence suggests that the switch to glycolysis in microglia may kick-start a cascade of events that ultimately leads to microglial dysfunction and Aß accumulation.

Monocytes exposed to plasma from patients with Alzheimer's disease undergo metabolic reprogramming.

The search for a blood-based biomarker that identifies Alzheimer's disease (AD) and can replace current invasive and expensive diagnostic tests, continues. The most extensively-examined peripheral marker is ß-amyloid (Aß) but the results are inconsistent across studies and do not reflect the changes that take place in the brain. Several studies have assessed possible proteomic signatures but with inconsistent findings, although increases in circulating inflammatory molecules are generally observed. Here, rather than focus on identifying changes in the circulation, we evaluated the effect of plasma from patients with mild cognitive impairment (MCI) and AD on the human monocyte-like cell line, THP-1 cells, and plasma from an AD mouse model on a mouse monocyte-macrophage cell line, J774.2 cells. Plasma from AD patients and the AD mouse model increased inflammatory molecules in the cells and these changes were accompanied by an increase in glycolysis. Interestingly, plasma from MCI patients exerted no significant effect on THP-1 cells. The possibility therefore exists that evaluating the effect of plasma on IL-8 and TNFα mRNA in THP-1 cells combined with analysis of glycolysis in these cells, may be the basis of an indicator that discriminates between AD and MCI and normal controls, but is unlikely to be useful in identifying early pathological changes.

Administration of a leptin antagonist during the neonatal leptin surge induces alterations in the redox and inflammatory state in peripubertal /adolescent rats.

The importance of the neonatal leptin surge in rodents in neurodevelopmental processes has aroused curiosity in its implication in other physiological systems. Given the role of leptin in neuro-immune interactions, we hypothesized that the neonatal leptin surge could have an effect on the oxidative and inflammatory stress situations of both systems. We blocked the neonatal leptin surge by a leptin antagonist and measured several parameters of oxidative and inflammatory stress in the spleen, hypothalamus and adipose tissue of peripubertal/adolescent rats. The treated rats showed lower activity of several antioxidant enzymes in the spleen and their leukocytes released lower levels of mitogen-stimulated IL-10 and IL-13 and higher levels of TNF-alpha. In conclusion, the neonatal leptin surge may have a key role in the establishment of adequate redox and inflammatory states in the immune system, which is important for the generation of adequate immune responses and to obtain and maintain good health.

Sex-dependent influence of chronic mild stress (CMS) on voluntary alcohol consumption; study of neurobiological consequences.

Alcohol use disorder and depression are highly comorbid, and both conditions exhibit important sexual dimorphisms. Here, we aimed to investigate voluntary alcohol consumption after 6weeks of chronic mild stress (CMS) in Wistar rats - employed as an animal model of depression. Male and female rats were investigated, and changes in several molecular markers were analysed in frontal cortex (FCx) and hippocampal formation (HF). CMS induced depressive-like responses in the forced swimming test - increased immobility time - in male and female animals, without affecting anhedonia (sucrose preference test) nor motor activity (holeboard); body weight gain and food intake were diminished only among CMS males. Voluntary alcohol consumption was evaluated in a two-bottle choice paradigm (ethanol 20% versus tap water) for 4 consecutive days; females exhibited a higher preference for alcohol compared to male animals. In particular, alcohol consumption was significantly higher among CMS females compared to CMS male animals. Remarkably, similar changes in both male and female animals exposed to CMS were observed regarding the expression levels of NCAM-140KDa (decrease), GFAP and CB1R expression (increase) within the FCx as well as for HF PSD-95 levels (increase). However, contrasting effects in males and females were reported in relation to synaptophysin (SYN) protein levels within the FCx, HF CB1R expression (a decrease among male animals but an increase in females); while the opposite pattern was observed for NCAM-140KDa protein levels in the HF. A decrease in CB2R expression was only observed in the HF of CMS-females. The present study suggests that male and female animals might be differentially affected by CMS regarding later voluntary alcohol consumption. In this initial approach, cortical SYN, and NCAM-140KDa, CB1R and CB2R expression within the HF have arisen as potential candidates to explain such sex differences in behaviour. However, the depression-alcoholism relationship still deserves further investigation.

Modulatory influences of estradiol and other anorexigenic hormones on metabotropic, Gi/o-coupled receptor function in the hypothalamic control of energy homeostasis.

The appetite suppressant actions of estradiol are due to its ability to attenuate orexigenic signals and potentiate anorexigenic signals. The work from my laboratory has shown that male guinea pigs are more sensitive to the hyperphagic and hypothermic effects of cannabinoids than their female counterparts. Cannabinoid sensitivity is further dampened by the activational effects of estradiol. This occurs via the hypothalamic feeding circuitry, where estradiol rapidly attenuates the cannabinoid CB1 receptor-mediated presynaptic inhibition of glutamatergic input onto anorexigenic proopiomelanocortin (POMC) neurons in the arcuate nucleus. This disruption is blocked by the estrogen receptor antagonist ICI 182,780, and associated with increased expression of phosphatidylinositol-3-kinase (PI3K). Moreover, the ability of estradiol to reduce both the cannabinoid-induced hyperphagia and glutamate release onto POMC neurons is abrogated by the PI3K inhibitor PI 828. The peptide orphanin FQ/nociceptin (OFQ/N) activates opioid receptor-like (ORL)1 receptors to hyperpolarize and inhibit POMC neurons via the activation of postsynaptic G protein-gated, inwardly-rectifying (GIRK) channels. We have demonstrated that the fasting-induced hyperphagia observed in ORL1-null mice is blunted compared to wild type controls. In addition, the ORL1 receptor-mediated activation of GIRK channels in POMC neurons from ovariectomized female rats is markedly impaired by estradiol. The estrogenic attenuation of presynaptic CB1 and postsynaptic ORL1 receptor function may be part of a more generalized mechanism through which anorexigenic hormones suppress orexigenic signaling. Indeed, we have found that leptin robustly suppresses the OFQ/N-induced activation of GIRK channels in POMC neurons. Furthermore, its ability to augment excitatory input onto POMC neurons is blocked by PI 828. Thus, estradiol and other hormones like leptin reduce energy intake at least partly by activating PI3K to disrupt the pleiotropic functions of Gi/o-coupled receptors that inhibit anorexigenic POMC neurons.

Sex-dependent effects of neonatal maternal deprivation on endocannabinoid levels in the adipose tissue: influence of diet.

Maternal deprivation (MD) during neonatal life has diverse long-term effects, including modification of metabolism. We have previously reported that MD modifies the metabolic response to high-fat diet (HFD) intake, with this response being different between males and females, while previous studies indicate that in mice with HFD-induced obesity, endocannabinoid (EC) levels are markedly altered in various brown and white adipose tissue depots. Here, we analyzed the effects of MD (24 h at postnatal day 9), alone or in combination with a HFD from weaning until the end of the experiment in Wistar rats of both sexes. Brown and white perirenal and subcutaneous adipose tissues were collected and the levels of anandamide (AEA), 2-arachidonoylglycerol (2-AG), palmitoylethanolamide (PEA), and oleoylethanolamide (OEA) were determined. In males, MD increased the content of OEA in brown and 2-AG in subcutaneous adipose tissues, while in females the content of 2-AG was increased in perirenal fat. Moreover, in females, MD decreased AEA and OEA levels in perirenal and subcutaneous adipose tissues, respectively. HFD decreased the content of 2-AG in brown fat of both sexes and OEA in brown and subcutaneous adipose tissue of control females. In contrast, in subcutaneous fat, HFD increased AEA levels in MD males and OEA levels in control and MD males. The present results show for the first time that MD and HFD induce sex-dependent effects on the main ECs, AEA, and 2-AG, and of AEA-related mediators, OEA and PEA, in the rat brown and white (visceral and subcutaneous) adipose tissues.

CB2 cannabinoid receptor is involved in the anti-inflammatory effects of leptin in a model of traumatic brain injury.

BACKGROUND AND PURPOSE: The rates for traumatic brain injury (TBI) have risen in the last decade. Studies in animal models and clinical trials have not yet resulted in an effective treatment for TBI. Leptin, a 16kDa peptidic hormone is mainly known as a regulator of energy balance and has been shown to exert neuroprotective effects in different models of brain pathology. In this study, we have assessed whether leptin exerts protective actions in a TBI mouse model. In addition, the possible implication of CB2 cannabinoid receptor in leptin actions has been explored, since it is known that the endocannabinoid system interacts with leptin and actively participates in brain recovery after lesions. METHODS: Swiss (CD1) male mice were subjected to weigh-drop model for TBI. Prior to the lesion, mice were injected with an antagonist of CB2 receptor (AM630) or the vehicle and immediately after TBI, they received leptin or vehicle treatment. Data were analyzed using a two-way ANOVA or the non-parametric test Kruskal-Wallis when appropriate. For correlation analyses, Spearman's rho test, followed by linear regression test, was used. RESULTS: TBI induced a neurological deficit, which was improved by leptin treatment. Leptin recovered several parameters affected by TBI, including the expression of cannabinoid receptors, axonal injury marker and neuroinflammatory components. The effects of leptin were prevented or reduced when it was administered in combination with the CB2 receptor antagonist, AM630. CONCLUSIONS AND IMPLICATIONS: Since some of the beneficial effects of leptin were not evident in the presence of AM630, our results suggest that CB2 receptor might be involved in the full expression of the neuroprotective effects of the hormone. These findings open new avenues for the study of leptin as a therapeutic treatment for TBI and enhance the importance of CB2 receptor in TBI pathophysiology and recovery.

Blockage of neonatal leptin signaling induces changes in the hypothalamus associated with delayed pubertal onset and modifications in neuropeptide expression during adulthood in male rats.

The neonatal leptin surge, occurring from postnatal day (PND) 5 to 13 and peaking at PND9 in rodents, is important for the development of neuroendocrine circuits involved in metabolic control and reproductive function. We previously demonstrated that treatment with a leptin antagonist from PND 5 to 9, coincident with peak leptin levels in the neonatal surge, modified trophic factors and markers of cell turnover and neuronal maturation in the hypothalamus of peri-pubertal rats. The kisspeptin system and metabolic neuropeptide and hormone levels were also modified. Here our aim was to investigate if the timing of pubertal onset is altered by neonatal leptin antagonism and if the previously observed peripubertal modifications in hormones and neuropeptides persist into adulthood and affect male sexual behavior. To this end, male Wistar rats were treated with a pegylated super leptin antagonist (5mg/kg, s.c.) from PND 5 to 9 and killed at PND102-103. The appearance of external signs of pubertal onset was delayed. Hypothalamic kiss1 mRNA levels were decreased in adult animals, but sexual behavior was not significantly modified. Although there was no effect on body weight or food intake, circulating leptin, insulin and triglyceride levels were increased, while hypothalamic leptin receptor, POMC and AgRP mRNA levels were decreased. In conclusion, alteration of the neonatal leptin surge can modify the timing of pubertal onset and have long-term effects on hypothalamic expression of reproductive and metabolic neuropeptides.