It is well established that hormones secreted by the hypothalamic-pituitary-ovarian axis play a preeminent role in control of female reproductive processes; however, there is accumulating evidence that neural mechanisms, including afferent, central and efferent connections, are involved in various phases of reproductive processes, e.g. neuroendocrine reflexes, blood flow regulation and pacing of rhythmic smooth muscle contractions induced by hormonal states. Dysfunctions follow denervation of reproductive organs such as disrupted estrous cycles, decreased sex steroid hormone secretion, failure of implantation and prolonged gestation. Explanations of many reproductive problems are hampered because fundamental questions remain about neurotransmitter substances involved in vascular control, smooth muscle control and sensory reflexes in reproductive organs. Likewise, location of ganglionic neurons and the nerve pathways which innervate organs is not fully understood. Thus, the primary aim of this present study is to determine the location of peripheral parasympathetic motor neurons which innervate the reproductive end organs such as vagina, cervix, uterine horns and oviducts in the female rat and to determine the type(s) of neurotransmitter substance(s) they contain. A focus of the proposed studies is to define the neurochemical anatomy of the parasympathetic motor ganglia which contribute nerves to the reproductive organs. Most previous work involved the clasic adrenergic and cholinergic systems; however, contemporary techniques have revealed many new putative peptide neurotransmitters that could function in control of blood flow and activation or inhibition of smooth muscle, i.e. vasoactive intestinal polypeptide (VIP) and neuropeptide-tyrosine (NPY). We will use immunohistochemical, histochemical and axonal tract tracing techniques to localize these substances in neurons which project to the reproductive system. In addition, this system will serve as a model to examine the co-existence of two transmitter substances within the same neuron; e.g. NPY and noradrenaline or VIP and acetylcholine. Data obtained from this study of the innervation of the female reproductive organs and their related ganglia will provide the basis to design experiments to further investigate functional influences of nerves on reproductive processes, to elucidate effects of reproductive system hormones on peripheral neurons innervating reproductive organs and define the functional components mediating neural-endocrine-reproductive end organ reflexes.
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