A woman’s fertility is dependent on the cascade of events leading up to ovulation. Defects in this ovulatory
process result in 25% of all female infertility cases, supporting the paramount role of ovulation in reproductive
success and providing a strong premise to explore mediators of the ovulatory process. We propose that
neurotensin is one of these pivotal regulators of the ovulatory process.
Ovulation is set in motion by the preovulatory LH surge which increases ovarian intrafollicular mediators
that act to bring about oocyte release. Our novel and exciting preliminary data indicate that neurotensin (NTS),
a small neuropeptide, is a key intrafollicular mediator of ovulation. This is based upon our findings that NTS is
one of the most differentially-expressed genes in the granulosa cells of the human ovulatory follicle, up to
15,000 fold after the ovulatory gonadotropin surge. Likewise, LH also rapidly and significantly increases NTS
mRNA in granulosa cells from rodent and monkey ovulatory follicles. Importantly, injection of a neurotensin
antibody into monkey preovulatory follicles blocked oocyte release resulting in luteinized unruptured follicles,
consistent with failure of ovulation. Similarly, mice lacking NTS expression form luteinized unruptured follicles
following LH/hCG administration, and a NTS receptor antagonist inhibits oocyte release in a novel in vitro
model of mouse ovulation. Yet, other than our preliminary data, nothing is known regarding the temporal
expression of NTS receptors or the function of NTS in ovulation and female fertility. These questions will be
addressed in this proposal through a collaborative approach utilizing the exceptional backgrounds, technical
expertise, and models of the Project Leaders. We will make use of a high-impact, translational model where
the granulosa and theca from human periovulatory follicles will be collected prior to and at three designated
times after hCG (early, late and postovulatory) to complement in vivo and in vitro studies performed with mice
and monkeys. The regulation of NTS and NTS receptor expression in the ovulatory follicle will be illuminated
and compared across women, monkeys and mice in Aim 1. The ovulatory functions stimulated by NTS in
granulosa, theca, cumulus, and endothelial cells of the follicle will be elucidated in Aim 2. The actions of NTS
on ovulation, as well as other key reproductive processes, will be revealed in mice and monkeys using mice
lacking NTS expression, NTS receptor antagonists, and NTS-neutralizing antibodies in Aim 3. A major strength
of this proposal is the collaborative interactions between Dr. Curry and Dr. Duffy to address the function of NTS
and its receptors in periovulatory events across multiple species, including exceptional human ovarian tissues
and in vivo studies of non-human primates, an animal model with high relevance to human reproductive
function. Thus, there is an exceptional degree of significance in understanding the basic tenets of oocyte
release which provides a fundamental platform to either improve outcomes for infertile women or conversely
provide targets to prevent oocyte release for female contraception.