Developmental sex differences in the peri-pubertal pattern of hypothalamic reproductive gene expression, including Kiss1 and Tac2, may contribute to sex differences in puberty onset.

The mechanisms regulating puberty still remain elusive, as do the underlying causes for sex differences in puberty onset (girls before boys) and pubertal disorders. Neuroendocrine puberty onset is signified by increased pulsatile GnRH secretion, yet how and when various upstream reproductive neural circuits change developmentally to govern this process is poorly understood. We previously reported day-by-day peri-pubertal increases (Kiss1, Tac2) or decreases (Rfrp) in hypothalamic gene expression of female mice, with several brain mRNA changes preceding external pubertal markers.

Bmal1 Is Required for Normal Reproductive Behaviors in Male Mice.

Circadian rhythms synchronize physiological processes with the light-dark cycle and are regulated by a hierarchical system initiated in the suprachiasmatic nucleus, a hypothalamic region that receives direct photic input. The suprachiasmatic nucleus then entrains additional oscillators in the periphery. Circadian rhythms are maintained by a molecular transcriptional feedback loop, of which brain and muscle aryl hydrocarbon receptor nuclear translocator-like protein 1 (BMAL1) is a key member.

A Novel Letrozole Model Recapitulates Both the Reproductive and Metabolic Phenotypes of Polycystic Ovary Syndrome in Female Mice.

Polycystic ovary syndrome (PCOS) pathophysiology is poorly understood, due partly to lack of PCOS animal models fully recapitulating this complex disorder. Recently, a PCOS rat model using letrozole (LET), a nonsteroidal aromatase inhibitor, mimicked multiple PCOS phenotypes, including metabolic features absent in other models. Given the advantages of using genetic and transgenic mouse models, we investigated whether LET produces a similar PCOS phenotype in mice.

Daily successive changes in reproductive gene expression and neuronal activation in the brains of pubertal female mice.

Puberty is governed by the secretion of gonadotropin releasing hormone (GnRH), but the roles and identities of upstream neuropeptides that control and time puberty remain poorly understood. Indeed, how various reproductive neural gene systems change before and during puberty, and in relation to one another, is not well-characterized. We detailed the daily pubertal profile (from postnatal day [PND] 15 to PND 30) of neural Kiss1 (encoding kisspeptin), Kiss1r (kisspeptin receptor), Tac2 (neurokinin B), and Rfrp (RFRP-3, mammalian GnIH) gene expression and day-to-day c-fos induction in each of these cell types in developing female mice.

Simultaneous detection of nuclear and cytoplasmic RNA variants utilizing Stellaris® RNA fluorescence in situ hybridization in adherent cells.

RNA fluorescence in situ hybridization (FISH) has long been an indispensable tool for the detection and localization of RNA and is increasingly becoming an important complement to other gene expression analysis methods. We detail a streamlined RNA FISH protocol for the simultaneous imaging of multiple RNA gene products and RNA variants in fixed mammalian cells. The technique utilizes fluorescently pre-labeled, short DNA oligonucleotides (20 nucleotides in length), pooled into sets of up to 48 individual probes.

Impaired GABAB receptor signaling dramatically up-regulates Kiss1 expression selectively in nonhypothalamic brain regions of adult but not prepubertal mice.

Kisspeptin, encoded by Kiss1, stimulates reproduction and is synthesized in the hypothalamic anteroventral periventricular and arcuate nuclei. Kiss1 is also expressed at lower levels in the medial amygdala (MeA) and bed nucleus of the stria terminalis (BNST), but the regulation and function of Kiss1 there is poorly understood. γ-Aminobutyric acid (GABA) also regulates reproduction, and female GABAB1 receptor knockout (KO) mice have compromised fertility.

Lack of functional GABAB receptors alters Kiss1 , Gnrh1 and Gad1 mRNA expression in the medial basal hypothalamus at postnatal day 4.

Background/aims: Adult mice lacking functional GABAB receptors (GABAB1KO) show altered Gnrh1 and Gad1 expressions in the preoptic area-anterior hypothalamus (POA-AH) and females display disruption of cyclicity and fertility. Here we addressed whether sexual differentiation of the brain and the proper wiring of the GnRH and kisspeptin systems were already disturbed in postnatal day 4 (PND4) GABAB1KO mice.

Methods: PND4 wild-type (WT) and GABAB1KO mice of both sexes were sacrificed; tissues were collected to determine mRNA expression (qPCR), amino acids (HPLC), and hormones (RIA and/or IHC).

The development of kisspeptin circuits in the Mammalian brain.

The neuropeptide kisspeptin, encoded by the Kiss1 gene, is required for mammalian puberty and fertility. Examining the development of the kisspeptin system contributes to our understanding of pubertal progression and adult reproduction and sheds light on possible mechanisms underlying the development of reproductive disorders, such as precocious puberty or hypogonadotropic hypogonadism. Recent work, primarily in rodent models, has begun to study the development of kisspeptin neurons and their regulation by sex steroids and other factors at early life stages.

Emerging concepts on the epigenetic and transcriptional regulation of the Kiss1 gene.

Kisspeptin and its receptor have been implicated as critical regulators of reproductive physiology, with humans and mice without functioning kisspeptin systems displaying severe pubertal and reproductive defects. Alterations in the expression of Kiss1 (the gene encoding kisspeptin) over development, along with differences in Kiss1 expression between the sexes in adulthood, may be critical for the maturation and functioning of the neuroendocrine reproductive system and could possibly contribute to pubertal progression, sex differences in luteinizing hormone secretion, and other facets of reproductive physiology. It is therefore essential to understand how Kiss1 gene expression develops and what possible regulatory mechanisms govern the modulation of its expression.

Assessment of epigenetic contributions to sexually-dimorphic Kiss1 expression in the anteroventral periventricular nucleus of mice.

The Kiss1 gene, which encodes kisspeptin and is critical for reproduction, is sexually differentiated in the hypothalamic anteroventral periventricular (AVPV)/rostral periventricular (PeN) nuclei. Specifically, female rodents have higher AVPV/PeN Kiss1 expression than males, but how this Kiss1 sex difference is induced in early development is poorly understood. Here, we explored the contribution of epigenetic mechanisms to the establishment of the AVPV/PeN Kiss1 sex difference, focusing on histone deacetylation and DNA methylation.

Regulation of Kiss1 expression by sex steroids in the amygdala of the rat and mouse.

Kisspeptin (encoded by the Kiss1 gene) is an important regulator of reproduction. In rodents, Kiss1 is expressed in two hypothalamic regions, the arcuate nucleus and anteroventral periventricular/ periventricular continuum, where it is regulated by sex steroids. However, the distribution, regulation, and functional significance of neural kisspeptin outside of the hypothalamus have not been studied and are poorly understood.

The apoptotic response in HCT116BAX-/- cancer cells becomes rapidly saturated with increasing expression of a GFP-BAX fusion protein.

Background: Many chemotherapeutic agents promote tumor cell death by activating the intrinsic pathway of apoptosis. Intrinsic apoptosis involves permeabilization of the mitochondrial outer membrane and the release of cytochrome c, a process that is controlled by proteins of the BCL2 gene family. Chemoresistance is often associated with abnormalities in concentrations of BCL2 family proteins.

BAX-dependent and BAX-independent regulation of Kiss1 neuron development in mice.

The Kiss1 gene and its product kisspeptin are important regulators of reproduction. In rodents, Kiss1 is expressed in the hypothalamic arcuate (ARC) and anteroventral periventricular (AVPV)/rostral periventricular (PeN) nuclei. In the AVPV/PeN, females have more Kiss1 and tyrosine hydroxylase (TH) neurons than males.

Sexual differentiation and development of forebrain reproductive circuits.

Males and females exhibit numerous anatomical and physiological differences in the brain that often underlie important sex differences in physiology or behavior, including aspects relating to reproduction. Neural sex differences are both region-specific and trait-specific and may consist of divergences in synapse morphology, neuron size and number, and specific gene expression levels. In most cases, sex differences are induced by the sex steroid hormonal milieu during early perinatal development.

A single nucleotide polymorphism in the Bax gene promoter affects transcription and influences retinal ganglion cell death.

Pro-apoptotic Bax is essential for RGC (retinal ganglion cell) death. Gene dosage experiments in mice, yielding a single wild-type Bax allele, indicated that genetic background was able to influence the cell death phenotype. DBA/2J(Bax+/-) mice exhibited complete resistance to nerve damage after 2 weeks (similar to Bax(-/-) mice), but 129B6(Bax+/-) mice exhibited significant cell loss (similar to wild-type mice).

Involvement of the Bcl2 gene family in the signaling and control of retinal ganglion cell death.

Retinal ganglion cell death by apoptosis is a well-established outcome in the glaucomatous pathology of the retina. Extensive research into the molecular events underlying this process show us that members of the Bcl2 gene family play a critical role in the activation and control of ganglion cell death. Perhaps the most critical molecule at play is the pro-apoptotic protein BAX.

Dominant inheritance of retinal ganglion cell resistance to optic nerve crush in mice.

Background: Several neurodegenerative diseases are influenced by complex genetics that affect an individual's susceptibility, disease severity, and rate of progression. One such disease is glaucoma, a chronic neurodegenerative condition of the eye that targets and stimulates apoptosis of CNS neurons called retinal ganglion cells. Since ganglion cell death is intrinsic, it is reasonable that the genes that control this process may contribute to the complex genetics that affect ganglion cell susceptibility to disease.

Mammary tumorigenesis in growth hormone deficient spontaneous dwarf rats; effects of hormonal treatments.

This study was carried out to investigate mammary tumorigenesis in growth hormone (GH) deficient spontaneous dwarf rats (SDR). At 50-60 days of age, the rats were divided into five groups. Group 1 received bovine (b) GH (prolonged release formulation) administered at a dose of 40-50 mg/kg body wt.