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

Leptin, the product of obese gene, is a secreting protein that exerts multiple biological functions by binding to its receptor. Leptin regulates nutrient intake and metabolism, and is secreted from adipocytes, which occupy most of the bone marrow cavity and constitute the microenvironment. Leptin not only plays an important role in the control of the proliferation and differentiation of normal primitive hematopoietic cells, but it also stimulates the growth and viability of leukemic cells. Leukemic cells of some patients with acute myeloid leukemia (AML), acute lymphoblastic leukemia, and chronic myeloid leukemia also express the leptin receptor. Furthermore, leptin also stimulates leukemic cell growth in vivo by promoting angiogenesis. These findings suggest the possibility that leptin and its receptor play roles in the pathophysiology of leukemia, and blockage of leptin binding to its receptor might have potential therapeutic benefits in the treatment of certain leukemias. This review discusses the biological characteristics of leptin and its receptor, the relation of leptin and its receptor with normal hematopoiesis, the relation of leptin and its receptor with AML and so on.
Animals ; Hematopoietic System ; Humans ; Leptin ; physiology ; Leukemia, Myeloid, Acute ; Receptors, Leptin ; physiology

Fat accumulation has been shown to play important roles in the development of obesity-related disorders such as atherosclerosis, diabetes mellitus and hypertension. Recent studies have shown that fat tissue is not a simple energy storage organ, but exerts important endocrine functions. These are achieved predominantly through release of adipocytokines, which include several novel molecules released by adipocytes like leptin, resistin, adiponectin or visfatin, as well as some more classical cytokines released possibly by inflammatory cells, like TNF-alpha and IL-6. Adipocytokines may affect cardiovascular, hepatic, muscular and metabolic function. In this review, the recent research work of adipocytokines will be discussed.
Adipokines ; physiology ; Adiponectin ; physiology ; Adipose Tissue ; chemistry ; physiology ; Humans ; Leptin ; physiology ; Resistin ; physiology

Adipose Tissue ; cytology ; physiology ; Animals ; Humans ; Leptin ; physiology ; Stromal Cells ; 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

This review article introduces the research advances in the pathophysiological mechanism of obesity in inducing pediatric bronchial asthma, including the role of leptin in obesity and asthma, the association of plasminogen activator inhibitor-1 with obesity and asthma, the association of adiponectin and interleukins with obesity and asthma, and the influence of neurotransmitter on asthma. In particular, this article introduces the latest research on the inhibition of allergic asthma through targeting at the nociceptor of dorsal root ganglion and blocking the signaling pathway of the nociceptor.
Asthma ; complications ; Humans ; Leptin ; physiology ; Nerve Growth Factor ; physiology ; Neurotransmitter Agents ; physiology ; Obesity ; etiology ; Plasminogen Activator Inhibitor 1 ; physiology

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

Leptin, an adipocyte-derived hormone, serves numerous physiological functions in the body, particularly during puberty and reproduction. The exact mechanism by which leptin activates the gonadotropin-releasing hormone (GnRH) neurons to trigger puberty and reproduction remains unclear. Given the widespread distribution of leptin receptors in the body, both central and peripheral mechanisms involving the hypothalamic-pituitary-gonadal axis have been hypothesized. Leptin is necessary for normal reproductive function, but when present in excess, it can have detrimental effects on the male reproductive system. Human and animal studies point to leptin as a link between infertility and obesity, a suggestion that is corroborated by findings of low sperm count, increased sperm abnormalities, oxidative stress, and increased leptin levels in obese men. In addition, daily leptin administration to normal-weight rats has been shown to result in similar abnormalities in sperm parameters. The major pathways causing these abnormalities remain unidentified; however, these adverse effects have been attributed to leptin-induced increased oxidative stress because they are prevented by concurrently administering melatonin. Studies on leptin and its impact on sperm function are highly relevant in understanding and managing male infertility, particularly in overweight and obese men.
Animals ; Humans ; Infertility, Male/physiopathology* ; Leptin/physiology* ; Male ; Obesity/complications* ; Overweight/complications* ; Reproduction/physiology*

Animals ; Humans ; Leptin ; genetics ; physiology ; Liver Cirrhosis ; etiology ; RNA, Messenger ; analysis ; Receptors, Cell Surface ; analysis ; physiology ; Receptors, Leptin ; Transforming Growth Factor beta ; genetics ; Transforming Growth Factor beta1

For the regulation of energy balance in various internal organs including gut, pancreas and liver, visceral adipose tissue and brain perform important sensing and signaling roles via neural and endocrine pathway. Among these, adipose tissue has been known as a simple energy-storing organ, which stores excess energy in triglyceride. However, it became apparent that adipocytes have various receptors related to energy homeostasis, and secrete adipocytokines by endocrine, paracrine and autocrine mechanisms. In this review, basic roles of adipocytes in energy homeostasis and the correlation between adipocyte signals and digestive diseases are discussed.
Adipocytes/*metabolism ; Adipokines/*physiology ; Adiponectin/physiology ; Digestive System Diseases/*metabolism ; *Energy Metabolism ; Homeostasis ; Humans ; Leptin/physiology ; Peroxisome Proliferator-Activated Receptors/physiology ; Resistin/physiology ; Signal Transduction