OBJECTIVEConditioned taste preference (CTP) is a taste learning reflex by which an animal learns to prefer a substance which tastes not well and has been studied with much interest in recent years. However, the neural substrates of CTP are less known. This study aimed to determine the possible neural path- ways of CTP and whether serum leptin level and the leptin receptor (OB-Rb) in the hind brain are involved following CTP formation.

METHODSWe established CTP of quinine in rats with a 2-bottle preference test. The serum leptin concentrations were detected, the expression of c-fos in the rat brain was tested to determine the nuclei in relation with establishment of CTR Finally, the OB-Rb mRNA expression was examined by RT-qPCR assay in parabrachial nucleus (PBN) and the nucleus of the solitary tract (NST) of the hind brain.

RESULTSCompared with control group, the level of serum leptin was higher in the CTP group (4.58 ± 0.52 vs 1.67 ± 0.25 µg/L, P < 0.01); increased c-fos positive cells were found in the anterior hypothalamus (AH, 221.75 ± 4.96 vs. 178.50 ± 6.63 cells/mm², P < 0.05), the basal lateral amygdala (BLA, 70.75 ± 6.17 vs 56.50 ± 3.62 cells/ mm², P < 0.05) and the nucleus of the solitary tract (NST, 41.25 ± 1.32 vs 32.50 ± 1.02 cells/mm², P < 0.05). But in ventromedial nucleus of the hypothalamus (VMH, 20.75 ± 2.73 vs 38.5 ± 1.54 per 1 mm², P < 005), PBN (21.50 ± 2.24 vs 36.25 ± 1.49 cells/mm², P < 0.05) and the central nucleus of the amygdala (CeA, 22.25 ± 1.53 vs 35.50 ± 2.11 cells/mm², P < 0.05), the number of c-fos positive cells was decreased in the CTP group. In addition, we found OB-Rb mRNA expression in PBN of CTP group rats was higher than that of control group (0.95 ± 0.055 vs 0.57 ± 0.034, P < 0.05), while there was no significant difference of OB-Rb mRNA expression in NST between the two groups.

CONCLUSIONNuclei AH, BLA, NST, VMH, PBN and CeA participate in the formation of CTP. Leptin and its receptor in PBN may be involved in the formation and maintenance of CTP.

Animals ; Conditioning (Psychology) ; Leptin ; blood ; Rats ; Receptors, Leptin ; physiology ; Rhombencephalon ; physiology ; Taste ; physiology

AIMTo determining whether the level of serum leptin altered and whether the expression of leptin receptor immunoreactivity changed following taste stimuli.

METHODSAfter intraoral infusions of chemical solutions, which included 3 mol/L sucrose, 5 mmol/L sodium saccharin, 0.1 mol/L NaCl, 0.01 mol/L HCl, 1 mmol/L quinine H2SO4 and 0.1 mol/L monosodium glutamate, serum leptin concentration were measured by using rat leptin RIA kit. Immunohistochemistry ABC method was used for brain sections with high-specify-goat antiserum against leptin receptors.

RESULTSComparing with the control group (intraoral infusion of distilled water), the level of serum leptin only in sweet group (sucrose an d saccharin) raised (P < 0.05). Many neuronal cell bodies and dendritic processes showed leptin receptors immunoreactivity (LR-IR) in many brain regions, such as amygdala, hypothalamus, parabrachial nucleus and nucleus of the solitary tract, which had intense relationship with taste and feeding. But the number of positive-stained cells showed no difference in aforementioned brain regions between the taste stimuli group and the control group.

CONCLUSIONAfter intraoral stimuli of sweet substances, the serum leptin concentration increased. LR-IR cells exist in amygdala which plays a critical role in the initiation and guidance of feeding. This findings led us study possible effects of leptin on taste responses. Probably, leptin influences food intake through the sense of taste.

Animals ; Brain ; physiology ; Eating ; Female ; Leptin ; blood ; metabolism ; Male ; Rats ; Rats, Sprague-Dawley ; Receptors, Leptin ; blood ; Taste

OBJECTIVELeptin is an adipocyte-derived hormone regulating body weight and energy balance in animals and human being. Although the physiological functions of leptin in human are still unclear, its secretion is closely related to fat mass and energy expenditure in both adults and children. This study investigated whether the plasma leptin level was reduced in connection with the weight loss during the neonatal period and try to find out the role of leptin in body weight regulation and energy balance of premature infants.

METHODSThe radioimmunoassay was used to determine the plasma leptin concentration. The first blood samples were obtained at the delivered, and then collected the samples every two days until the infants' body weight recovered to the birth weight or above. At the same time, the essential fluid and energy for the patients were supplied to keep their physiological functions. One person was appointed to take responsibility to examine the body weight, body length and head circumference. Then computed out their Kaup index from the first day to the seventh or twelfth day.

RESULTSA total of 26 premature infants were selected into the study, of which 14 cases were male and 12 female, and their gestational age ranged from 30 to 36 weeks. There was a significantly positive correlation between the premature newborns' body weight loss and their plasma leptin levels (the 1st day: n = 26, r = 0.766; the 3rd day: n = 26, r = 0.636; the 5th day: n = 26, r = 0.629; the 7th day: n = 26, r = 0.717; the 9th-12th day: n = 24, r = 0.587; P < 0.01). The time of body weight loss and the plasma leptin level which declined to extremely low were positively correlated. (r = 0.611, P < 0.01). The time when body weight loss declined to extremely low in 26 premature infants ranged form the 3rd to the 9th day after birth [(5.2 +/- 1.6) day], and that of the plasma leptin levels ranged form the 3rd to the 8th day after birth (4.7 +/- 1.4) day. The maximal ranges of the body weight loss and the plasma leptin decrease in 26 premature infants were (6.5 +/- 3.0)% and (59.6 +/- 11.3)%, respectively. In addition, there were significantly positive correlations among the plasma leptin level, the premature newborns' body length (the 1st day: n = 26, r = 0.609, P < 0.01; the 3rd day: n = 26, r = 0.419, P < 0.05; the 5th day: n = 26, r = 0.583, P < 0.01; the 7th day: n = 26, r = 0.626, P < 0.01; the 9th-12th day: n = 24, r = 0.482; P < 0.05), and the Kaup index (the 1st day: n = 26, r = 0.634; the 3rd day: n = 26, r = 0.534; the 5th day: n = 26, r = 0.542; the 7th day: n = 26, r = 0.611; the 9th-12th day: n = 24, r = 0.539; P < 0.01). Although the head circumference correlated positively with the plasma leptin level at the first week after the delivery (the 1st day: n = 26, r = 0.580, P < 0.01; the 3rd day: n = 26, r = 0.417, P < 0.05; the 5th day: n = 26, r = 0.426; P < 0.01). There was a lower correlation between them one week after the delivery (the 7th day: n = 26, r = 0.369; the 9th-12th day: n = 24, r = 0.323; P > 0.05).

CONCLUSIONThere was a significantly positive correlation between the plasma leptin level and the premature newborns weight loss. Leptin may participate in the regulation of energy balance and body weight of premature infants during neonatal life. Leptin may play an important role in growth and development of premature infants.

Body Weight ; physiology ; Humans ; Infant, Newborn ; Infant, Premature ; Leptin ; blood ; Radioimmunoassay ; Time Factors ; Weight Loss ; physiology

OBJECTIVETo investigate plasma leptin concentrations in adolescent female dancers and to determine whether leptin has some effects on their bone mineral density (BMD) and bone turnover markers.

METHODSSixty dancers aged 15-17 years and 77 healthy controls were enrolled in the study. Bone mineral density (BMD) and body composition were detected by dual energy X-ray absorptiometry. Serum leptin concentrations were measured by radioimmunoassay (RIA). Two bone turnover markers, bone-specific alkaline phosphatase (BAP) and tartrate-resistant acid phosphatase(TRACP), were determined by ELISA.

RESULTSThe dancers had a lower fat mass and a lower leptin level than the controls, while they had a relatively higher BMD of the total body and legs after adjustment for BMI and age. The levels of bone resorption and formation of markers were higher in the dancers than in the controls. Leptin was positively correlated with BMI, body weight, fat mass, and percentage of body fat. In dancers, Leptin was positively correlated with the BMD of the total body and the left leg. However, after adjustment for BMI, no correlation of serum leptin concentrations with BMD values was found in either dancers or controls. Nor correlation was found between leptin and bone turnover markers after adjustment for BMI.

CONCLUSIONThe leptin profile is different between the controls and the dancers with a lower BMI and a lower fat mass. Circulating plasma leptin level depends on BMI and is not a direct determinant of BMD in Chinese adolescent dancers.

Adolescent ; Biomarkers ; blood ; Bone Density ; physiology ; Dancing ; Female ; Humans ; Leptin ; blood

OBJECTIVETo explore the factors influencing insulin resistance in children with different nutritional status during pubertal development.

METHODSThree hundred children with simple obese aged 7 to 17 years, and 300 normal healthy children and 300 children with malnutrition, matched for age (+/- 3 months) and height (+/- 2 cm), were selected. Fasting serum levels of leptin, insulin, glucose, total cholesterol (TC), triglycerides (TG), low density lipoprotein-cholesterol (LDL-C) and high density lipoprotein-cholesterol (HDL-C) were measured for them.

RESULTSLevels of fasting serum insulin in obese children, except for boys at Tanner stage I and girls at Tanner stage II, were higher than those in normal and malnutrition children (P < 0.01). Average serum level of leptin in obese boys and girls at varied Tanner stages was higher than that in normal children, and higher in normal children than that in children with malnutrition (P<0.01). Serum level of TG in obese children [(1.53 +/- 0.13) mmol/L] was higher than that in normal ones [(1.12 +/- 0.10) mmol/L] and in children with malnutrition [(1.03 +/- 0.09) mmol/L]. There was no significant difference in levels of fasting blood glucose and other blood lipids between the three groups of children. Insulin sensitivity decreased with pubertal development and its index reversely correlated with Tanner stage and serum level of leptin (r=-0.27 and -0.36, respectively, P<0.01).

CONCLUSIONObesity (BMI), serum level of leptin and pubertal development were independent risk factors for insulin resistance in children aged 7 to 17 years.

Adolescent ; Body Mass Index ; Child ; Estradiol ; blood ; Growth Hormone ; metabolism ; Humans ; Insulin ; blood ; Insulin Resistance ; Leptin ; blood ; physiology ; Male ; Malnutrition ; blood ; Obesity ; blood ; physiopathology ; Puberty ; physiology ; Testosterone ; blood

Chronic obstructive pulmonary disease (COPD) is one of the major diseases worldwide. Nutritional depletion is a common problem in COPD patients and also an independant predictor of survival in these patients. Many data are helpful for determining nutritional depletion, including anthropometric measurement, laboratory markers, body composition analysis (fat-free mass and lean mass), and body weight. The mechanism of nutritional depletion in patients with COPD is still uncertain. It may be associated with energy/metabolism imbalance, tissue hypoxia, systemic inflammation, and leptin/orexin disorders. In patients with nutritional depletion, growth hormone and testosterone can be used for nutritional therapy in addition to nutrition supplementation.
Body Composition ; physiology ; Humans ; Intracellular Signaling Peptides and Proteins ; blood ; Leptin ; blood ; Lung Diseases, Obstructive ; blood ; complications ; Neuropeptides ; blood ; Nutrition Assessment ; Nutrition Disorders ; diagnosis ; etiology ; Orexins ; Weight Loss ; physiology

OBJECTIVESTo study the role of leptin in the development boys during their puberty and its relationship with insulin (INS), growth hormone (GH), estradiol (E2) and testosterone (T).

METHODSOne hundred and fifty boys with simple obese aged 7 to 17 years, 150 normal healthy boys and 150 boys with malnutrition matched for age (+/- 3 months) and height (+/- 2 cm) were selected. Serum levels of leptin, INS, GH, E2 and T were measured for them.

RESULTSSerum level of leptin in obese group was significantly higher than that in normal group, and that in normal group was significantly higher than that in malnourished group. In the all three groups, serum level of leptin increased with age first until peak value, then began to decrease, with peak value of 6.96 microg/L at ages of 10-11 y in obese group, 10.25 microg/L at ages of 11-12 y in normal group and 5.08 microg/L at ages of 11-12 y in malnourished group. Serum level of leptin increased steadily from Tanner stages G1 to G2, then began to decrease steadily in G2 to G4. Serum level of leptin increased again in stage G5. Serum level of INS in boys increased steadily with age from 7 to 17 years old. Serum levels of GH, T and E2 in boys began to increase since 10-11 years old. Serum level of leptin positively correlated with serum level of INS and negatively correlated with serum levels of GH and T, but not correlated with serum level of E2.

CONCLUSIONSLeptin may promote pubertal development of boys, but not the determinant factor in triggering and maintaining their pubertal development. Re-increase in level of leptin during stage G5 could inhibit secretion of GH, and signalize the end of puberty in boys.

Adolescent ; Body Height ; physiology ; Body Mass Index ; Body Weight ; physiology ; Child ; Estradiol ; metabolism ; Growth Hormone ; metabolism ; Humans ; Leptin ; blood ; physiology ; Male ; Puberty ; physiology ; Testosterone ; metabolism

OBJECTIVESTo study the roles of leptin in the development during puberty in girls and the its relationship with insulin (INS), growth hormone (GH), estradiol (E(2)) and testosterone (T).

METHODSOne hundred and fifty girls with simple obese aged 7 to 17 years, and 150 normal healthy girls and 150 girls with malnutrition matched for age (+/- 3 months) and height (+/- 2 cm) were selected. Serum levels of leptin, INS, GH, E(2) and T were measured for them.

RESULTSTheir serum level of leptin positively correlated with body mass index (BMI) and age. Serum level of leptin in girls increased steadily from Tanner stage B(1) to stage B(5). At Tanner stage B(2), serum level of leptin in the normal groups (7.72 microg/L) was not significantly different from that in those with malnutrition (7.36 microg/L), but significantly lower than that in the obese groups (12.85 microg/L). At other Tanner stages, there was significant difference in serum level of leptin among obese, normal and malnutrition groups. Serum level of leptin correlated negatively with serum GH and positively with serum INS, but not correlated with E(2) and T.

CONCLUSIONSLeptin may play a role in triggering development during puberty in girls. Serum level of leptin at Tanner stage B(2) may be the threshold dose to trigger the onset of puberty in girls. Quickly increasing level of leptin at Tanner stage B(5) may inhibit the increase of GH, which ushered the end of puberty in girls.

Adolescent ; Body Height ; physiology ; Body Mass Index ; Body Weight ; physiology ; Child ; Female ; Growth Hormone ; metabolism ; Humans ; Leptin ; blood ; physiology ; Puberty ; physiology ; Testosterone ; metabolism

OBJECTIVE: To examine the serum visfatin, adiponectin and leptin levels in patients with polycystic ovarian syndrome (PCOS), and to explore the basis of the pathogenesis of PCOS. METHODS: A PCOS group (n=73) and a healthy control group (n=75) were included in the study, which were matched in age and body mass index (BMI). Serum visfatin, adiponectin, leptin, sex hormone levels, and metabolic parameters were measured by enzyme-linked immunosorbent assay (ELISA) or radioimmunoassay (RIA). RESULTS Serum levels of fasting insulin(Fins), homeostatic model assessment for insulin resistance (HOMA-IR), testosterone (T), luteinizing hormone (LH), and prolactin (PRL) in the PCOS group were significantly higher than those in the healthy group(all P<0.05),and follicle-stimulating hormone (FSH) level was significantly decreased in the PCOS group. The visfatin and leptin levels in the PCOS group increased significantly than those in the healthy group [PCOS group: (95.30+/-31.90) and (11.10+/-3.87) microg/L; healthy group: (73.20+/-20.30) and (7.21+/-2.47) microg/L,P<0.001]. The adiponectin level was significantly lower than that in the healthy group [PCOS group: (4.21+/-1.17) mg/L; healthy group:( 6.39+/-1.53) mg/L,P<0.001]. Pearson correlation analysis showed that visfatin level was negatively related to adiponectin levels (r=-0.452 and -0.378, P<0.01), but positively related to leptin and HOMA-IR levels in both the PCOS group and the healthy group (r=0.379-0.556, all P<0.01). The correlation remained between the visfatin and HOMA-IR levels in the PCOS group after correcting the influence of BMI. CONCLUSION Patients with PCOS have high visfatin and leptin levels but low adiponectin levels. Visfatin levels are positively related to insulin resistance.
Adiponectin ; blood ; Adolescent ; Adult ; Case-Control Studies ; Female ; Humans ; Insulin Resistance ; physiology ; Leptin ; blood ; Nicotinamide Phosphoribosyltransferase ; blood ; Polycystic Ovary Syndrome ; blood ; Young Adult

INTRODUCTIONThere are very few data about relations between leptin and bone mineral density (BMD) in regular haemodialysed patients. We aimed to examine the relationship of serum leptin levels with BMD values in dialysed patients. We also assessed whether leptin is a significant predictor of BMD in haemodialysed patients.

MATERIALS AND METHODSLeptin levels were studied using commercially available kits and BMD values were calculated using dual energy X-ray absorptiometry (DEXA) at femoral neck and distal radius in 74 (30 men and 44 women ) haemodialysis patients.

RESULTSBMD values at the femoral neck and distal radius did not differ significantly between the 2 genders. BMD at the distal radius correlated positively with bone alkaline phosphatase (BAP) (r = 0.503, P = 0.005) in male patients and correlated positively with phosphorus (r = 0.343, P = 0.02) in female patients. The time ondialysis treatment was longer in men (59 +/- 48 vs 44 +/- 41) but the difference was not statistically significant. Leptin levels were negatively correlated with BMD at the distal radius (r = -0.250 and P = 0.03) in all patients. Serum leptin levels were also correlated with body mass index (BMI) in all the patients (r = 0.749 and P = 0.001) and in both genders (r = 0.653 and P = 0.001 in women, r = 0.704 and P = 0.001 in men). In multivariate regression analysis, it was found that leptin level was not an independent determinant of BMD at all skeleton sites measured.

CONCLUSIONSThere was significant difference between the 2 genders with reference to leptin levels, BMI, phosphorus and creatinine. Serum leptin levels are not significant predictors of BMD in the current study.

Absorptiometry, Photon ; Adolescent ; Adult ; Aged ; Bone Density ; physiology ; Female ; Humans ; Leptin ; blood ; Male ; Middle Aged ; Renal Dialysis ; Young Adult