Expression of Muscarinic Receptor Types in the Primate Ovary and Evidence for Nonneuronal Acetylcholine Synthesis1

Abstract

The presence of muscarinic receptors (MR) in the ovary of different species has been recognized, but the identity of these receptors as well as ovarian sources of their natural ligand, acetylcholine (ACh), have not been determined. Because luteinized human granulosa cells (GC) in culture express functional MR, we have determined whether the group of the related MR subtypes, M1R, M3R, and M5R, are present in vivo in human and rhesus monkey ovaries. To this end, ribonucleic acids (RNAs) of different human and monkey ovaries as well as RNAs from human GC and monkey oocytes were reverse transcribed and subjected to PCR amplification, followed by sequencing of the amplified complementary DNAs. Results obtained showed that M1R, M3R, and M5R messenger RNAs are present in adult human and monkey ovaries; oocytes express exclusively the M3R subtype, whereas GC express M1R and M5R. To determine the ovarian source(s) of the natural ligand of these ACh receptors, we attempted to localize the enzyme responsible for its synthesis with the help of a monoclonal antibody recognizing choline acetyltransferase for immunohistochemistry. In neither human nor monkey sections did we detect immunoreactive choline acetyltransferase-positive fibers or nerve cells, but, surprisingly, GC of antral follicles showed prominent staining. To determine whether GC can produce ACh, human cultured GC derived from preovulatory follicles were analyzed using a high pressure liquid chromatography technique. The results showed that these cells contained ACh in concentrations ranging from 4.2-11.5 pmol/10(6) cells. Samples of a rat granulosa cell line likewise contained ACh. Thus, the ovary contains multiple MR, and GC of antral follicles are able to synthesize ACh, the ligand of MR. We propose that ACh may serve as an as yet unrecognized factor involved in the complex regulation of ovarian function in the primate, e.g. regulation of cell proliferation or progesterone production.

Superior mesenteric ganglion neural modulation of ovarian angiogenesis, apoptosis and proliferation by the neuroactive steroid allopregnanolone

“…98 around the theca cells. 50 The wide variety of neurotransmitters present in this pathway includes SP, calcitonine gene-related peptide, neuropeptide Y and acetylcholine, all with known effects in ovarian vasculature 69,[103][104][105] and angiogenic properties, [106][107][108][109] it is possible that the SMG incubation with ALLO induced the modulation of some of these mechanisms.…”

“…There is evidence of the existence of GABAergic neurons and GABAergic signaling in the sympathetic ganglia that innervates the ovary 65‐67 . In addition, the mammalian ovary expresses a wide variety of receptors for neurotransmitters, such as NA, 68 acetylcholine 69 and GABA, 70 amongst others, which have distinct functions on ovarian structures. However, the rapid modulation of neural peripheral pathways or in situ ovarian receptors by neuroactive steroids is still unknown.…”

Traced on the Timeline: Discovery of Acetylcholine and the Components of the Human Cholinergic System in a Primitive Unicellular Eukaryote Acanthamoeba spp.

“…ACh of a non-neuronal source plays an important role in several human tissues like ovaries and in renal cortex of rabbits as has been reported in the past. − Additionally, ACh along with its receptors and synthetic/lytic enzymes has been reported in the human respiratory system, gastrointestinal tract, endothelial, glia, circulating blood cells like platelets and monocytes . ACh also has been implicated in the regulation of ovarian functions like production of progesterone .…”

Nerve Growth Factor: A Dual Activator of Noradrenergic and Cholinergic Systems of the Rat Ovary

“…To study the effects of NGF on ACh production in the ovaries, we used six prepuberal rats ( Table 1). We used prepuberal rat ovaries because, at this age, there is no ovulation and no corpora lutea; thus, we can study the effect of NGF mainly in GCs (21,22). The rats were euthanized, and both ovaries were removed through an anterior incision in the midline of the abdomen.…”

“…Regarding cycle recruitment, we found a decrease in the number of healthy antral follicles and an increase in atretic antral follicles. Since the GCs of healthy antral follicles express ChAT (21,22), the reduction in their number could explain the reduction in acetylcholine levels after NGF treatment. The increase in atretic antral follicles could be an NGF-dependent atretic process mediated by its low-affinity NGFR (also termed as p75NTR) (58).…”