Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Carrie K. Vance

Committee Member

Andrew J. Kouba

Committee Member

Scott T Willard

Committee Member

Jean M. Feugang

Committee Member

David Kabelik

Date of Degree

8-6-2021

Original embargo terms

Visible to MSU only for 6 months

Document Type

Dissertation - Open Access

Major

Animal Physiology

Degree Name

Doctor of Philosophy

Degree Name

Doctor of Philosophy (Ph.D)

College

College of Agriculture and Life Sciences

College

College of Agriculture and Life Sciences

Department

Animal Physiology Program

Abstract

Today, amphibian extinction rates are rising at an alarming rate. Captive assurance colonies have become a hedge against extinction, and often must employ assisted reproductive technologies (ART) in species that do not readily breed in captivity. One technique that can be utilized in assisted breeding is hormone therapy, which involves the treatment of individuals with exogenous reproductive hormones. The primary delivery method used in most breeding programs is intraperitoneal injection, but many institutions either lack the training necessary to conduct this invasive procedure, or require veterinary staff to perform them, thus delaying breeding events. Therefore, there is interest in alternate means of hormone delivery. In particular, the use of intranasaladministration. The following studies were conducted to determine the efficacy of hormones administered via alternate delivery routes, and to investigate the pathways taken by both intraperitoneal and intranasal delivery methods. Through these studies, wefound that intranasal administration gonadotropin releasing hormone (GnRH), is effective at eliciting sperm production in male anurans. In order to investigate the paths taken by intraperitoneal and intranasal GnRH, I used a treatment of hormone-conjugated quantum dot nanoparticles and employed both in-vivo fluorescence imaging techniques and histological imaging. The evidence presented here suggests that the route traveled by nasally-delivered GnRH is largely swallowed and accumulates in the GI tract, buteventually diffuses into the bloodstream in large enough concentrations to exact a reproductive response. The other hormone investigated here was arginine vasotocin (AVT), a hormone known to elicit calling and amplexus behaviors in amphibians. Though limited reproductive behaviors were observed in these studies, I found that both intranasal and intraperitoneal delivery of AVT resulted in water uptake and retention in males. Fluorescence imaging revealed that AVT, when administered nasally, is largely swallowed, similarly to GnRH. Intraperitoneally-injected AVT, however, was found to accumulate in large concentrations within the interrenal gland and kidney, where it likely stimulated the observed osmoregulatory effects. This study therefore offers insight into an effective alternate hormone delivery method (nasal) and provides compelling evidence into the organs wherein GnRH and AVT act following two different delivery routes.

Sponsorship

USDA Biophotonics Initiative #58-6402-018, Institute of Museum and Library Sciences MG-30-17-0052-17

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