| dc.identifier.uri | http://hdl.handle.net/11401/76568 | |
| dc.description.sponsorship | This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree. | en_US |
| dc.format | Monograph | |
| dc.format.medium | Electronic Resource | en_US |
| dc.language.iso | en_US | |
| dc.publisher | The Graduate School, Stony Brook University: Stony Brook, NY. | |
| dc.type | Dissertation | |
| dcterms.abstract | Hypothalamic kisspeptin-expressing neurons are a critical relay system that conveys information about hormonal and nutritional status to gonadotropin-releasing hormone neurons. PI3K/mTOR signaling is linked to the regulation of hypothalamic kisspeptin expression and of gonadotropin release by nutritional status. Whether kisspeptin neuron-specific PI3K/mTOR signaling participates in the regulation of the kisspeptin system and gonadotropin release under normal and under metabolic challenges is unknown. Phosphatase and tensin homolog (PTEN) is the principal negative regulator of the PI3K/mTOR signaling pathway. In addition, PTEN expression and function is regulated by estrogen, the sex-steroid hormone principally responsible for the sexually dimorphic expression of hypothalamic kisspeptin and the feedback regulation of luteinizing hormone (LH) release. This dissertation addresses PTEN’s role in the control of kisspeptin expression and gonadotropin release by sex-steroid hormones and by nutritional status, using mice with a kisspeptin cell-specific deletion of PTEN (Kiss-PTENKO). Compared to controls, the number of kisspeptin neurons was higher in the anteroventral periventricular nucleus (AVPV) of Kiss-PTENKO males but not in females. Hypertrophic kisspeptin neurons were observed in arcuate nucleus (ARC) of Kiss-PTENKO mice, and also in the AVPV of Kiss-PTENKO females. In Kiss-PTENKO mice ARC kisspeptin fiber distribution was unaltered after gonadectomy (GDX) and the LH response to GDX was attenuated. Kiss-PTENKO females but not males were subfertile, however no genotype effects were observed on cyclicity or ovarian function. Compared to controls, AVPV and ARC kisspeptin-expressing neurons from Kiss-PTENKO females but not males showed a significant increase in pS6 expression, suggesting mTOR hyperactivation. Next, we tested whether the increase in kisspeptin neuron mTOR signaling in Kiss-PTENKO females prevents the negative effects of fasting on kisspeptin expression and LH release. Fasting significantly decreased LH levels in WT but not in Kiss-PTENKO females. Immunoblotting of the mediobasal hypothalamus (MBH) and preoptic area (POA) showed that in control animals fasting did not decrease kisspeptin protein. In contrast, kisspeptin protein levels in both brain regions were significantly higher in fasted and fed Kiss-PTENKO females. Therefore, kisspeptin cell-specific PTEN signaling regulates gonadotropin release and hypothalamic kisspeptin expression in response to the availability of endogenous sex hormones and nutrients. | |
| dcterms.abstract | Hypothalamic kisspeptin-expressing neurons are a critical relay system that conveys information about hormonal and nutritional status to gonadotropin-releasing hormone neurons. PI3K/mTOR signaling is linked to the regulation of hypothalamic kisspeptin expression and of gonadotropin release by nutritional status. Whether kisspeptin neuron-specific PI3K/mTOR signaling participates in the regulation of the kisspeptin system and gonadotropin release under normal and under metabolic challenges is unknown. Phosphatase and tensin homolog (PTEN) is the principal negative regulator of the PI3K/mTOR signaling pathway. In addition, PTEN expression and function is regulated by estrogen, the sex-steroid hormone principally responsible for the sexually dimorphic expression of hypothalamic kisspeptin and the feedback regulation of luteinizing hormone (LH) release. This dissertation addresses PTEN’s role in the control of kisspeptin expression and gonadotropin release by sex-steroid hormones and by nutritional status, using mice with a kisspeptin cell-specific deletion of PTEN (Kiss-PTENKO). Compared to controls, the number of kisspeptin neurons was higher in the anteroventral periventricular nucleus (AVPV) of Kiss-PTENKO males but not in females. Hypertrophic kisspeptin neurons were observed in arcuate nucleus (ARC) of Kiss-PTENKO mice, and also in the AVPV of Kiss-PTENKO females. In Kiss-PTENKO mice ARC kisspeptin fiber distribution was unaltered after gonadectomy (GDX) and the LH response to GDX was attenuated. Kiss-PTENKO females but not males were subfertile, however no genotype effects were observed on cyclicity or ovarian function. Compared to controls, AVPV and ARC kisspeptin-expressing neurons from Kiss-PTENKO females but not males showed a significant increase in pS6 expression, suggesting mTOR hyperactivation. Next, we tested whether the increase in kisspeptin neuron mTOR signaling in Kiss-PTENKO females prevents the negative effects of fasting on kisspeptin expression and LH release. Fasting significantly decreased LH levels in WT but not in Kiss-PTENKO females. Immunoblotting of the mediobasal hypothalamus (MBH) and preoptic area (POA) showed that in control animals fasting did not decrease kisspeptin protein. In contrast, kisspeptin protein levels in both brain regions were significantly higher in fasted and fed Kiss-PTENKO females. Therefore, kisspeptin cell-specific PTEN signaling regulates gonadotropin release and hypothalamic kisspeptin expression in response to the availability of endogenous sex hormones and nutrients. | |
| dcterms.available | 2017-09-20T16:50:39Z | |
| dcterms.contributor | Kritzer, Mary F. | en_US |
| dcterms.contributor | Acosta-Martinez, Maricedes | en_US |
| dcterms.contributor | Talmage, David | en_US |
| dcterms.contributor | Whitaker-Azmitia, Patricia. | en_US |
| dcterms.creator | Negron, Ariel L. | |
| dcterms.dateAccepted | 2017-09-20T16:50:39Z | |
| dcterms.dateSubmitted | 2017-09-20T16:50:39Z | |
| dcterms.description | Department of Neuroscience | en_US |
| dcterms.extent | 86 pg. | en_US |
| dcterms.format | Application/PDF | en_US |
| dcterms.format | Monograph | |
| dcterms.identifier | http://hdl.handle.net/11401/76568 | |
| dcterms.issued | 2016-12-01 | |
| dcterms.language | en_US | |
| dcterms.provenance | Made available in DSpace on 2017-09-20T16:50:39Z (GMT). No. of bitstreams: 1
Negron_grad.sunysb_0771E_13141.pdf: 9949110 bytes, checksum: cfc24944ed7788297e15f87f0dc6885a (MD5)
Previous issue date: 1 | en |
| dcterms.publisher | The Graduate School, Stony Brook University: Stony Brook, NY. | |
| dcterms.subject | Kisspeptin, mTOR, PTEN | |
| dcterms.subject | Neurosciences -- Endocrinology | |
| dcterms.title | The Role of PTEN Signaling in the Function and Development of the Sexually Dimorphic Kisspeptin System | |
| dcterms.type | Dissertation | |
