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Recombinant Leptin (recombinant + leptin)

Distribution by Scientific Domains

Medical Sciences	100%

Selected Abstracts

Effect of leptin on motility, capacitation and acrosome reaction of human spermatozoa

INTERNATIONAL JOURNAL OF ANDROLOGY, Issue 6 2009
H. W. R. Li
Summary Leptin is a polypeptide hormone with important roles in reproduction. It has been detected in human seminal plasma as well as on human ejaculated spermatozoa. This study aimed at studying the possible role of leptin in regulating human sperm functions. Immunofluorescent staining was used to study the expression of leptin and its receptor. The correlation between the concentration of leptin and soluble leptin receptor (ObRs) in seminal plasma as measured by enzyme-linked immunosorbant assay and sperm motility parameters measured by computer-assisted sperm analyais (CASA) was determined. The effects of recombinant leptin on human sperm motility, capacitation and acrosome reaction as measured by chlortetracycline staing were also studied. Leptin immunoreactivity was demonstrated at the equatorial and neck regions of human spermatozoa, whereas that of ObRs was shown up on the tail. After Percoll separation, spermatozoa with high density had more intense leptin immunoreactivity compared with those with low density. No significant correlation was found between seminal plasma concentration of leptin/ObRs and sperm motility parameters. After incubation with recombinant human leptin for either 3 h or overnight, there was no change in all the CASA motility parameters determined and percentages of capacitated and acrosome-reacted spermatozoa. We concluded that leptin does not have a significant effect on motility and capacitation/acrosome reaction in human ejaculated mature spermatozoa. Its role in male reproduction is yet to be determined. [source]

Leptin and leptin receptor in human seminal plasma and in human spermatozoa

INTERNATIONAL JOURNAL OF ANDROLOGY, Issue 6 2003
T. Jope
Summary Leptin, a 167 amino acid peptide, is known to influence the gonads via direct and indirect effects. Recent studies provide contradictory proposition about the peripheral impact of leptin in the male gonads. Thus, we examined leptin and its receptors in human seminal plasma and in human ejaculated spermatozoa by Western blot technique and fluorescence microscopy. In seminal plasma we found a free leptin band (16 kDa) by an anti-leptin polyclonal antibody. Incubation of seminal plasma with recombinant leptin caused a statistically significant increase in the amount of free leptin (p < 0.01) and supports this finding. Furthermore, a soluble leptin receptor (145 kDa) was found in human seminal plasma in the same specimen. We also detected a 145-kDa leptin receptor isoform in ejaculated spermatozoa as a possible target of leptin action in the male genital tract, which was localized at the tail of spermatozoa by immunofluorescence microscopy only. This receptor was significantly associated with the intactness of sperm plasma membranes. Spermatozoa with deteriorated membranes contained 49.2 ± 6.9% leptin receptor signal intensity compared with spermatozoa having intact membranes (p < 0.01). This finding is difficult to interpret and may be caused by a leakage of OB-R due to loss of membrane integrity. In conclusion, these data provide further hints for a peripheral role of leptin in the male genital tract, possibly, by an interaction between leptin and spermatozoa via sperm leptin receptors. [source]

Severe pulmonary metastasis in obese and diabetic mice

INTERNATIONAL JOURNAL OF CANCER, Issue 12 2006
Akinori Mori
Abstract Although obesity is known as a risk factor for several human cancers, the association of obesity with cancer recurrence and metastasis remains to be characterized. Here, B16-BL6 melanoma and Lewis lung carcinoma cells were intravenously injected into diabetic (db/db) and obese (ob/ob) mice. The number of experimental lung colonies was markedly promoted in these mice when compared with C57BL/6 mice. In contrast, tumor growth at the implanted site was comparable when cells were inoculated orthotopically. The use of B16-BL6 cells stably transfected with the luciferase gene revealed that the increased metastasis reflected a difference mainly within 6 hr after the intravenous inoculation of tumor cells. Administration of recombinant leptin in ob/ob mice abolished the increase in metastasis early on as well as the decrease in the splenic NK cell number. In addition, depletion of NK cells by an anti-asialo-GM1 antibody abrogated the enhanced metastasis in db/db mice. These results demonstrate that metastasis is markedly promoted in diabetic and obese mice mainly because of decreased NK cell function during the early phase of metastasis. © 2006 Wiley-Liss, Inc. [source]

Leptin Uptake by Serotonergic Neurones of the Dorsal Raphe

JOURNAL OF NEUROENDOCRINOLOGY, Issue 6 2002
M. C. Fernández-Galaz
Abstract The effects of leptin on food intake, metabolism, sleep patterns and reproduction may be mediated, in part, by the midbrain serotonergic systems. Here, we report on the distribution of neurones that accumulate leptin in the raphe nuclei of male and female rats after intracerebroventricular administration of mouse recombinant leptin labelled with digoxigenin. Direct leptin-targeted cells were present in the periventricular grey, pontine and raphe nuclei. Confocal microscopy revealed that raphe neurones which accumulated leptin were predominantly serotonergic. The temporal pattern of leptin accumulation by raphe neurones showed a marked gender difference: 6 h after leptin administration, all male and female rats showed massive leptin binding in the dorsal raphe, while 30 min after leptin treatment, only 10% of male rats exhibited leptin-labelled cells in contrast to 50% of females. The present observations reveal that leptin can be selectively accumulated by serotonergic neurones in the raphe nuclei and that this mechanism is gender specific. These findings support the idea that the midbrain serotonergic system is an important mediator of the effects of leptin on brain function and may provide an explanation for gender differences in metabolism regulation and its coordination with higher functions of the brain. [source]

Free-Choice Alcohol Consumption in Mice After Application of the Appetite Regulating Peptide Leptin

ALCOHOLISM, Issue 5 2001
F. Kiefer
Background: Leptin has been shown to regulate food intake and energy expenditure. Very recently, associations of elevated leptin plasma levels during alcohol withdrawal with alcohol craving have been observed in humans. Therefore, we tested the hypothesis that the application of exogenous leptin modulates voluntary alcohol consumption in mice. Methods: Sixteen mice (129/Sv x C57BL/6J) were habituated to ethanol consumption over a time period of 3 months. After a basal 2-week free-choice drinking phase, mice were separated into two groups (n= 8) according to weight and alcohol consumption. They received recombinant leptin (1 mg/kg) versus saline intraperitoneally daily for 10 days. After 4 days of free-choice consumption of ethanol (16% v/v) versus water, ethanol was withdrawn at day 4 and replaced at day 6 to test the occurrence of an alcohol deprivation effects. Fluid intake was evaluated by controlling the weight of the drinking tubes daily. Results: Free-choice ethanol consumption after withdrawal was significantly elevated in mice after intraperitoneal injection of 1 mg/kg leptin (alcohol deprivation effect), but not during basal drinking. Conclusion: We suggest that leptin may enhance motivation for alcohol consumption in habituated mice after alcohol withdrawal. [source]