bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2024.10.07.617027

Tracking gonadotropin-releasing hormone-mediated movement in-vivo using quantum dot nanoparticles: insights into pathways leading to sperm release

Julien, A. R.·Kouba, A. R.·Kabelik, D.·Feugang, J. M.·Willard, S. T.·Kouba, C.
View original source ↗Export metadata ↓

Abstract

As the number of conservation breeding programs for at-risk amphibians increase, application of assisted reproductive technologies (ARTs) has likewise grown, with hormone therapy being the most widely utilized technique. Significant interest has been raised for viable alternatives to traditional intracelomic injection for hormone treatment that may be simpler, require less hormone, induce a faster response and be more suitable for animals of different sizes or for minimal contact. We utilized quantum dot (QD) nanoparticles conjugated to GnRHa (GnRHa-QDs) as a means of monitoring exogenous GnRHa dispersal through living Fowlers toads to investigate how delivery route may affect hormone pathway and efficacy after intracelomic, nasal, and oral administration. Real-time GnRHa-QD movement was tracked using in vivo imaging while hormone binding and QD aggregation were validated using fluorescence microscopy and measurements of spermiation responses following the administration of unconjugated GnRHa, unconjugated QDs, and GnRHa-QDs GnRHa alone was found to induce spermiation in 58.3%, 76.9% and 92.3% of males when administered by intracelomic, oral and nasal routes, respectively. When given through intracelomic injection GnRHa-QD caused spermiation and dispersed throughout the abdominal cavity to then aggregate within the brain, heart, liver, gastrointestinal (GI) tract, kidneys, and testes while unconjugated QDs did not. By contrast, GnRHa-QDs administered by oral or nasal routes were observed moving to the tympanic membrane and down the throat to the GI tract of the toads, but only nasal-administered GnRHa-QDs showed organ aggregation and were only found in the kidneys. Unconjugated QDs exhibited similar in vivo signal dispersal as their conjugated counterparts initially but did not aggregate in any organs over time nor induce spermiation. Through the use of novel QD hormone conjugates, in vivo imaging, and histology we were able to gain insight into how hormone pathways and efficacy might be impacted by delivery route which result in variations in physiological response to hormone treatment.

Explore related subjects

physiologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Julien, A. R., Kouba, A. R., Kabelik, D., Feugang, J. M., Willard, S. T., Kouba, C.. 2024-10-11. Tracking gonadotropin-releasing hormone-mediated movement in-vivo using quantum dot nanoparticles: insights into pathways leading to sperm release. https://doi.org/10.1101/2024.10.07.617027

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

DEPP1 connects nutrient and oxygen availability to maintenance of muscle mass

Nutrients and oxygen are sensed within the muscle to control growth and disruption of either signal is sufficient to lead to muscle atrophy. While nutrient limitation is sensed via a conserved transcriptional atrophy program (commonly referred to as atrogenes) dictated via the Forkhead box O (FoxO) transcription factors, how low oxygen promotes muscle loss remains unknown. Accordingly, the downstream mechanisms that initiate muscle loss when oxygen and nutrients are limiting are only partly understood. Here, we find Hypoxia Inducible Factor (HIF), the master regulator of our adaptation to low oxygen, is necessary and sufficient to mediate muscle loss under hypoxia in mice. RNA sequencing in skeletal muscle isolated from starved or hypoxic mice identifies Decidual Protein Induced by Progesterone 1 (Depp1), which is induced in skeletal muscle when nutrients or oxygen is limiting via FoxO1 and HIF activation, respectively. Whole body Depp1 loss in mice reduces muscle loss under fasting and hypoxia and skeletal muscle Depp1 overexpression is sufficient to mediate muscle atrophy. Mechanistically, Depp1 localizes to the mitochondria and is necessary to control autophagy activation and mitochondrial degradation in skeletal muscle. Taken together, our studies nominate Depp1 as a new atrogene necessary for muscle loss under multiple atrophy scenarios involving FoxO and HIF.

physiology↗
bioRxiv2026

The CREB-regulated co-activators 2/3, have a role, in vivo, in osteoblastic gene expression.

Many hormones and substances acting through G-protein coupled receptors and protein kinase A (PKA) activation inhibit the salt-inducible kinases (SIKs) by phosphorylation. SIKs tonically phosphorylate CREB-regulated transcriptional coactivators (CRTC1, 2 and 3), sequestering them in the cytoplasm and, thus, preventing their translocation into the nucleus. Once in the nucleus, CRTCs bind CREB family member transcription factors and enhance their activity. We and others have shown that parathyroid hormone (PTH) activation of PKA and resultant SIK2/3 inhibition allows CRTC2/3 nuclear translocation. One of the major actions of CRTC2/3 in the osteoblast lineage is the regulation of transcription of Rankl, as well as other PTH-controlled genes. However, little is known about the role of these co-activators in the osteoblast lineage in vivo. Here, we have investigated whether there are basal effects in vivo on bone examined at 2 different ages of conditional deletion of these two co-activators in the osteoblast lineage using Col2.3-Cre. We found significant increases in body weight, length, bone mineral density, bone volume/total volume, trabecular thickness and number with decreased trabecular separation in young (2 months old) male mice, all of which dissipated by 6 months of age. Female mice showed minimal changes in the bone phenotype at either age. Nevertheless, there were gene expression changes in bones of both sexes at both ages, and in particular decreases in Rankl, Runx2 and Sost, and accompanying changes in Wnt pathway genes. These effects may explain the changes in the bone phenotype in the young male mice, but it is notable that there is a sexual dimorphism in the action of CRTC2 and CRTC3. Overall, the work supports the data from research in vitro and forms a basis for investigation of the role of these co-activators in PTH action in vivo.

physiology↗
bioRxiv2026

Cholinergic impairment in the dorsal motor nucleus of the vagus during experimental Alzheimer's disease

Cholinergic neurons in the dorsal motor nucleus of the vagus (DMN) in the brainstem are a key source of efferent vagus nerve fibers that regulate vital functions, including heart rate and inflammation. Whether the integrity of DMN cholinergic neurons is affected during Alzheimer's disease (AD) remains unknown. Here, in female and male mice with experimental AD (5xFAD), which exhibit age-dependent memory impairment, basal forebrain cholinergic neurodegeneration, and microglial alterations, we observe a reduction in cholinergic neuron density in the DMN at 6 and 10 months of age. Furthermore, while an important physiological function of DMN cholinergic signaling, such as suppression of heart rate, is preserved in control mice upon electrical DMN stimulation, the extent of suppression diminishes with age in both female and male 5xFAD mice. In addition, while electrical DMN stimulation lowers pro-inflammatory cytokine levels in control mice subjected to endotoxemia, this anti-inflammatory effect is diminished with age in 5xFAD mice, with females showing earlier dysfunction at 6 months. These results reveal previously unrecognized age-dependent cholinergic deficits in the DMN and disrupted brain - to - periphery vagus nerve circuits in experimental AD. These findings advance our understanding of AD mechanisms and are of interest for the development of conceptually novel therapies.

physiology↗