Evidence suggests that the role played by the adipocyte-derived hormone leptin in female reproductive physiologyis mediated in part by neurons located within the ventral premammillary nucleus (PMV). female mice and results demonstrate that the acute effect of leptin on LepR PMV neurons was identical for both sexes. Pharmacological inhibition of PI3K prevented the acute leptin-induced change in neuronal activity of LepR PMV neurons indicating a PI3K-dependent mechanism of leptin action. Similarly mice with genetically disrupted PI3K signaling in LepR PMV neurons failed to alter cellular activity in response to leptin. Moreover the leptin-induced depolarization was dependent on a putative TRPC channel. In contrast the leptin-induced-hyperpolarization required the activation of a putative Katp channel. Collectively these results suggest that PI3K signaling in LepR PMV neurons is essential for leptin-induced alteration in cellular activity and these data may suggest a cellular correlate in which leptin contributes to the initiation of reproductive development. Introduction The adipocyte-derived hormone leptin has a profound influence on energy and glucose homeostasis. Leptin has also been implicated in pubertal development and fertility (Clayton et al. 1997 Mantzoros et al. 1997 Quinton et al. 1999 Leptin’s role in sexual development is highlighted by the fact that leptin deficiency or lack of the leptin receptor (LepR) results in a failure of sexual maturity (Coleman 1978 Zhang et al. 1994 Tartaglia et al. 1995 Moreover leptin is required for pubertal development in normal female mice and rescues the infertility of ob/ob mice (Ahima et al. 1996 1997 probably signaling directly in the brain at what time the body is ready for sexual maturation (de Luca et al. 2005 Leptin also increases luteinizing hormone (LH) secretion during negative energy balance in many species including humans (Ahima MDV3100 et al. 1996 Nagatani et al. 1998 Watanobe et al. 1999 Chan et al. 2003 Welt et al. 2004 Together these data suggest that leptin may be acting directly in the brain to initiate reproductive development. Importantly recent MDV3100 evidence suggests that leptin may act directly within the ventral premammillary nucleus (PMV) to control many parameters of the reproductive physiology (Clayton et al. 1997 Mantzoros et al. 1997 Quinton et al. 1999 Donato et al. 2009 2011 Interestingly leptin has recently been shown to activate ～75% of the neurons that express leptin receptors within the PMV (Leshan et al. 2009 Leshan et al. (2009) further demonstrated that PMV neurons that express leptin receptor directly innervate gonadotropin-releasing hormone (GnRH) neurons highlighting a potential role of PMV neurons in stimulating LH secretion from the pituitary gland. Together these data demonstrate that although great strides have been made in understanding the Mouse monoclonal to CD18.4A118 reacts with CD18, the 95 kDa beta chain component of leukocyte function associated antigen-1 (LFA-1). CD18 is expressed by all peripheral blood leukocytes. CD18 is a leukocyte adhesion receptor that is essential for cell-to-cell contact in many immune responses such as lymphocyte adhesion, NK and T cell cytolysis, and T cell proliferation. effects of leptin on PMV neurons as they relate to mammalian fertility and pubertal development the intracellular signaling pathway and channel(s) underlying leptins acute effects within the PMV remain undefined. The arcuate nucleus has received significant attention MDV3100 with respect to the acute effects of leptin on cellular activity and may serve as a model system for the possible leptin-induced effects on cellular activity in other CNS nuclei (e.g. PMV). Importantly leptin’s excitatory and inhibitory effects within the hypothalamic and brainstem nuclei share the intracellular signaling cascade phosphoinositide 3 kinase (PI3K) (Spanswick et al. 1997 Cowley et al. 2001 van den Top et al. 2004 Williams and Smith 2006 Williams et al. 2007 Hill et al. 2008 In the arcuate nucleus leptin depolarizes arcuate POMC neurons via a PI3K-dependent activation of a putative TRPC channel (Hill et al. 2008 Qiu et al. 2010 while at the same time leptin hyperpolarizes arcuate NPY/AgRP neurons via a PI3K-dependent activation of a Katp channel (Spanswick et al. 1997 van MDV3100 den Top et al. 2004 We therefore tested the hypothesis that PI3K signaling in PMV neurons that express the leptin receptor LepR PMV neurons is necessary for normal leptin responsiveness in the PMV. Materials and Methods Subjects The mice with this study were housed in the University or college of Texas Southwestern Medical Center Animal Resource Center inside a light- (12 h on/12 h off) and temp- (21-23°C) controlled environment. They were fed standard chow diet (Harlan Teklad Global Diet) and experienced access to water. All experiments were performed in accordance with the guidelines founded by the National Institute of Health Guidebook for the Care and.