Rodent pests have eaten our food and transmitted diseases to us for millennia. There are an estimated 300 million introduced Norway or brown rats in the U.S. that cause $27 billion of economic losses annually. Historically the strategy has been to kill rat pests through a variety of methods but primarily by using poison baits that are anticoagulant rodenticides. In addition to all of the problems associated with using poison bait, e.g. poisoning nontarget animals/pets, children under the age of 6, and contaminating the environment, poison does not address the problem. A non-lethal strategy that has significant potential to manage rodent pest number is fertility control. But thus far effective control of free-ranging wildlife, such as small, nocturnal rodents, has not been achieved because distribution to dose rats must be via an oral route. The industrial chemical 4-vinylcyclohexene diepoxide (VCD) accelerates the natural process of atresia leading to depletion of rat ovarian follicles causing ovarian failure and permanent sterility. Follicle depletion occurs when VCD is given in repeated intraperitoneal daily doses and on average, complete elimination of primordial/primary follicles and premature ovarian failure occur by day 58 following the onset of dosing and in mice causes infertility. To date VCD induced follicle depletion has been achieved by intraperitoneal administration. However to develop and commercialize a product to cause wild rat infertility it must be given orally in a bait. This Phase I application aims to test the following hypothesis in three specific aims. Oral administration of VCD to rats will lead to complete depletion of ovarian follicle populations, resulting in infertility demonstrating feasibility for development of a fertility control bait for rats.
Aim 1. Determine the dose needed to deplete primordial ovarian follicles in rats by oral exposures to VCD.
Aim 2. Determine the time course over which VCD completely depletes ovarian follicle populations.
Aim 3. Determine the pharmacokinetics of VCD excretion. Results from Phase I experiments will define the dose and duration of VCD exposure necessary to cause complete ovarian follicle depletion. These results will enable us to obtain sufficient information to progress to a Phase II application to develop an oral bait and baiting protocol to manage wildlife rodent populations. Rats are being targeted in these studies, with the understanding that rats are more resistant to VCD than mice. Thus, success with rats, can easily be translated to mice. Furthermore, rats are the primary target pest species based on the enormous economic and significant public health risks they pose both by their contamination and destruction of our food supplies and the dangerous rodenticide control approaches currently being used to manage rat populations. PHS 398/2590 (Rev. 11/07) Page Continuation Format Page
Management of wild rats is critical to minimize agriculture and property damage and the spread of infectious diseases. Lethal approaches introduce poison into the environment and consequently are being targeted for removal from over the counter availability. The goal of this project is to provide data to support the feasibility of using the industrial chemical 4-vinylcyclohexene diepoxide (VCD) to ultimately develop an environmentally neutral permanent rodent fertility control bait to manage wild rat populations