Evidence for a cholinergic secretory innervation of the guinea-pig endometrium

Cyantraniliprole impairs reproductive parameters by inducing oxidative stress in adult female wistar rats

Cyantraniliprole is a synthetic insecticide used to control pests of up to 23 different types of crops. It is able to modulate ryanodine-like calcium channels, which are widely found in the organism of insects and mammals. The objective of this research was to verify the possible reproductive effects of adult female Wistar rats exposure to cyantraniliprole. Animals (67 days old) were exposed to the chemical at doses of 10 or 150 mg/kg/day, orally, for 28 consecutive days (control animals received only the vehicle). Vaginal secretions were collected during the exposure period to assess the regularity of the estrous cycle; the liver, kidneys, pituitary gland, adrenal gland, uterus, and ovaries were collected and weighed; reproductive organs were assessed for histopathological evaluation and for biochemical markers of oxidative stress and progesterone plasma level was measured. Both doses caused negative changes in the morphology and redox system of the uterus and ovaries. Animals exposed to 10 mg/kg also exhibited higher level of plasma progesterone, elevated levels of lipid peroxidation in reproductive organs, increased superoxide dismutase activity in the uterus and glutathione peroxidase activity on the ovary, while the 150 mg/kg group exhibited an increment in estrous cycle length and diminished uterine glandular epithelium. Based on these results, we conclude that cyantraniliprole may have acted as an endocrine disruptor, and its effects are mediated by oxidative stress.

Serotonin regulates contractile activity of the uterus in non-pregnant rabbits

Serotonin (5-HT) can stimulate the cholinergic system of the uterus by indirect actions on the modulation of reflexes and a direct action on smooth muscles. We investigated the role of 5-HT in the regulation of the cholinergic activity in the uterine parts of non-pregnant rabbits. The right vagus or pelvic nerve and the left sympathetic trunk were stimulated by an electrical field, and the uterine contractile activity was evaluated by measuring the amplitude and frequency of slow wave electromyogram (EMG), with the surface of microelectrodes applied to the uterus bottom, body, and cervix, respectively. Double stimulation of the vagus or pelvic nerve and the sympathetic trunk increased the frequency and the amplitude of the slow wave EMG in all the uterine parts. Furthermore, the administration of exogenous 5-HT increased the vagus or pelvic induced EMG activity in all parts of the uterus. Overall our results demonstrate that 5-HT enhances the vagus contractile activity with a magnitude of the effect decreasing from the bottom to the cervix, whereas 5-HT enhances the pelvic nerve contractile functions with a magnitude of the response increasing from the bottom to the cervix. The administration of droperidol, a 5-HT3 and 4 receptor inhibitor, and spiperone, a 5-HT2 receptor antagonist, inhibited the effect of the serotoninergic fibers of the sympathetic trunk to increase the vagus and pelvic nerve EMG activity. These data suggest that 5-HT stimulation of the parasympathetic nerves results in the induction of uterine contraction via the activation of 5-HT2, 3, and 4 receptor subfamilies.

Expression of cystic fibrosis transmembrane conductance regulator in paracervical ganglia

The cystic fibrosis transmembrane conductance regulator (CFTR) is an important protein that acts as a chloride channel and regulates many physiological functions, including salt transport and fluid flow. Mutations in the gene encoding the CFTR protein cause cystic fibrosis. CFTR is expressed in the epithelial cells of the lungs, pancreas, intestines, and other organs. In the peripheral and central nervous system, CFTR expression has been detected in the neurons of rat brains, ganglion cells of rat hearts, human hypothalamus, human spinal cord, and human spinal and sympathetic ganglia. However, CFTR has not been identified in other parts of the nervous system. In this study, we used immunohistochemistry, in situ hybridization, and laser-assisted microdissection (LMD) followed by reverse transcriptase (RT) PCR to identify CFTR proteins and messenger RNA in human and rat paracervical ganglion cells. CFTR and its gene expression were both detected in paracervical ganglion cells, a finding that might link this important protein to the neuronal regulation of female urogenital function. These findings could provide new insights into the symptoms related to the reproductive system frequently observed in female cystic fibrosis patients.

Nitric oxide induces endometrial secretion at implantation time

BACKGROUND

Uterine cervical secretory cells receive a sympathetic cholinergic secretomotor innervation. Glandular nitric oxide (NO) production has been proposed to be a prerequisite for muscarine-induced carbohydrate secretion from endometrial glands and cervical glands at ovulation time and from the seminal vesicle glands. Nitric oxide has also been suggested to have a significant role in the process of implantation and early pregnancy in the mouse, a process, which has also been compared with an inflammatory response.

METHODS

The carbohydrate secretion from everted guinea pig uterine horns placed in organ baths was estimated. Polymerase chain reaction was performed in order to identify the isoforms of nitric oxide synthase (NOS). results. Carbamylcholine chloride (Carbachol) induced carbohydrate secretion of the endometrium, whereas L-NNA and L-NAME inhibited the Carbachol-induced secretion. The isomer D-NAME had no effect on Carbachol-induced secretion. The NO donor GTN induced carbohydrate secretion of the endometrium. The addition of the nitrergic inhibitor of soluble guanylyl cyclase (sGC) ODQ to Carbachol and to the NO donor GTN gave a reduced response. No synergism was seen when the sGC stimulator YC-1 was applied together with Carbachol. Three isoforms of NOS - endothelial NOS (eNOS), cytokine-inducible NOS (iNOS), and neuronal (nNOS) - were identified at implantation time and may take place in the endometrial cell.

CONCLUSIONS

The results of this study suggest that glandular NO production is a prerequisite for the autonomic nervous modulation of endometrial secretion in the guinea pig and that NO may play a role in the implantation time.

Nitric oxide increases endocervical secretion at the ovulatory phase in the female

BACKGROUND

Uterine cervical mucus is crucial for reproduction, facilitating sperm transport and survival in certain mammals. Cholinergic autonomic nervous secretory innervation has been established, and modulation of secretion by prostaglandins and non-steroidal anti-inflammatory drugs has been postulated. It has been suggested that glandular nitric oxide (NO) production is a prerequisite for the autonomic cholinergic nervous modulation of cervical, endometrial, and the seminal vesicle secretion in the guinea pig. Most secretory genital tract cells, female as well as male, seem to display NO synthase activity.

METHODS

Cervical secretion at ovulation time was studied in 10 women with regular menstruation. In an in vivo model with repeated collection of mucus samples during four 60-min periods, the amount of mucus was estimated in a control experimental series and in an experimental series following sublingual administration of the NO donor nitroglycerin.

RESULTS

This nitroglycerin administration markedly increased cervical secretion, while no changes in cervical secretion were seen in the control experimental series.

CONCLUSIONS

The results suggest that glandular NO production increases cervical secretion. Thus, cervical secretion may, apart from hormonal regulation, be influenced by the autonomic nervous system, and in addition, NO may be a prerequisite for this influence. This in turn may have implications on fertilization and fertility regulation.

Nitric oxide as putative second messenger in nerve-induced cervical gland secretion in the guinea-pig

Uterine cervical secretory cells receive a sympathetic cholinergic secretomotor innervation. It has been suggested that glandular nitric oxide (NO) production is a prerequisite for muscarinic-induced carbohydrate secretion in the endometrium and the seminal vesicle. A similar pattern for nerve-induced carbohydrate secretion in the cervix could be assumed. Nitric oxide synthase (NOS) activity was evaluated via formation of L-citrulline from L-arginine. The NADPH-diaphorase nitroblue technique was used for histochemical investigation. The cervix with the adjacent hypogastric nerve was placed in an isolated organ bath and the secretion was evaluated as an amount of carbohydrate. A calcium-dependent formation of citrulline was found in the cervix indicating NO formation. Strong NADPH-staining cells were found in the glandular ducts and in the glandular linings of the cervix. Stimulation of the hypogastric nerve induced carbohydrate secretion, which was inhibited by N-nitro-L-arginine methyl ester (L-NAME). D-NAME did not affect the secretory response. Carbachol and the NO donor glyceryl trinitrate (GTN) induced carbohydrate secretion in the cervical glands. No synergistic effect was noted probably due to an all-or-none type of secretion. N-nitro-L-arginine (L-NNA) and L-NAME inhibited carbachol-induced secretion. The results suggest that glandular NO production is a prerequisite for the autonomic nervous modulation of cervical secretion in the guinea-pig. This could have implications regarding fertility and fecundity.

Does nitric oxide act as a cellular messenger in muscarinic endometrial secretion in the guinea-pig?

Uterine secretory cells receive a sympathetic cholinergic secremotor innervation. Nitric oxide (NO) has been suggested to be a second messenger of neurogenic modulated glandular secretion of the seminal vesicle. Thus a similar pattern for nervous induced carbohydrate secretion of the endometrium was assumed. The nitric oxide synthase (NOS) activity was estimated via formation of L-citrulline from L-arginine and histochemically with the nicotinamide-adenine dinucleotide phosphate diaphorase (NADPH-d) nitro blue technique. The carbohydrate secretion from everted uterine horns placed in organ baths was estimated. A calcium dependent formation of citrulline was found in the uterine horn suggesting an NOS activity. Strong NADPH staining cells were found in the glandular ducts of the endometrium and in the epithelial linings of the oviduct. Carbachol induced carbohydrate secretion of the endometrium while N-nitro L-arginin (L-NNA) and N-nitro L-arginin methyl ester (L-NAME) inhibited the carbachol induced secretion. The isomer D-NAME had no effect on carbachol induced secretion. When L-arginine was administered together with L-NNA no inhibitory effect on carbachol induced secretion was seen. L-arginine only had no effect on carbohydrate secretion. The NO donor glyceryl tritrate increased carbohydrate secretion but no synergistic effect was seen in combination with carbachol. The results suggest that glandular NO production is a prerequisite for muscarinic carbohydrate secretion of the endometrium.

Distribution of neurons innervating the uterus of the pig

The distribution of neurons innervating the uterus of the pig was studied with the use of fluorescent retrograde tracer Fast Blue. Tracer injections were made into the uterine cervix, pericervical, middle and perioviductal part of the right uterine horn. After tracer injection into the uterine cervix tracer-positive neurons were found bilaterally in the inferior mesenteric ganglia, paracervical ganglia, paravertebral ganglia L1-S3 and dorsal root ganglia Th10-L4 and S2-S3. After tracer injection into the pericervical part of the right uterine horn the distribution of tracer-positive neurons resembled the one described earlier, except the tracer-positive neurons were absent in the left dorsal root ganglia. After tracer injection into the middle part of the right uterine horn tracer-positive neurons were found in the ipsilateral inferior mesenteric ganglion, bilaterally in the paracervical ganglia and in the ipsilateral paravertebral ganglia (L2-L6). Injection of the tracer into the perioviductal part of the right uterine horn revealed tracer-positive neurons bilaterally in the inferior mesenteric ganglia and paracervical ganglia and single cells in the ipsilateral paravertebral ganglia.

Sympathetic regulation of fructose secretion in the seminal vesicle of the guinea-pig

Fructose secretion of everted guinea-pig seminal vesicles was studied in vitro. Carbachol produced dose dependent increase in fructose secretion. The effect was blocked by scopolamine but not by hexamethonium, mecamylamine, tetrodotoxin or previous denervation. High concentrations of acetylcholine also increased fructose secretion. This response was not augmented by physostigmine. Methoxamine reduced secretion. Methoxamine, terbutaline, clonidine and vasoactive intestinal peptide counteracted carbachol. Field stimulation produced increased secretion that was not blocked by autonomic drugs, tetrodotoxin or previous denervation. Stimulation of the hypogastric nerve produced frequency dependent increase in fructose secretion. The effect was blocked by tetrodotoxin and scopolamine but not enhanced by physostigmine. If the hypogastric nerve was stimulated close to the seminal vesicle the response was unaffected by hexamethonium but proximal stimulation was blocked. After chronic proximal denervation of the hypogastric nerve, stimulation close to the seminal vesicle produced enhanced response. Destruction of the peripheral ganglia at the base of the seminal vesicle abolished the response. Sections showed that most secretory nerves enter the organ at its base. Phentolamine or yohimbine but not prazosine or propranolol or guanethidine enhanced the secretory response to distal hypogastric nerve stimulation. Tyramine counteracted the response but after reserpinization it was enhanced by tyramine. It is concluded that the secretory cells of the guinea-pig seminal vesicle have a sympathetic secretomotor innervation by short cholinergic neurones with a preganglionic supply via the hypogastric nerve. Inhibitory alpha 1 and beta 2-adrenoreceptors are present on the cells but neurogenic adrenergic inhibition of the secretion is essentially prejunctional and due to activation of inhibitory alpha 2-receptors on the secretomotor nerves.

The bovine tubouterine junction: general innervation pattern and distribution of adrenergic, cholinergic, and peptidergic nerve fibers

The innervation of the bovine tubouterine junction was studied in sexually mature heifers using antisera against various neuronal markers and a modified acetylcholinesterase method. The vast majority of the nerve fibres in the bovine tubouterine junction belongs to the sympathetic nervous system; peptidergic and cholinergic fibers are restricted to characteristic locations. The endosalpinx in the adovarian portion of the terminal tubal segment is poorly innervated. The mucosa of the aduterine portion and of the tubouterine transitional region proper receives a strikingly dense innervation, which is observed mainly in combination with a strong vascularisation of specialised mucosal structures. In the endometrium, perivascular nerves accompany the ascending spiral arteries but sporadic contacts between nerve fibres and uterine glands are also observed. From the muscular coat the inner longitudinal layer of the terminal tubal segment is more richly supplied by nerve fibres than the intermediate circular and outer longitudinal layers of the tubouterine junction. No changes in the innervation pattern were seen during the different stages of the sexual cycle.

Characterization and distribution of cholinesterase activity in mouse uterine horns: changes in estrous cycle

1. Both butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) are present in the mouse uterus, BChE being more abundant. 2. Their molecular forms were sequentially solubilized by different extraction media obtaining three ChE fractions whose specific activity was different, depending on the stage of the estrous cycle: hydrosoluble (estrous: 75.5 +/- 6.6 and diestrous: 47.9 +/- 8.7 mU/mg prot); detergent-soluble or amphiphilic (estrous 26.6 +/- 2.4 and diestrous 14.7 +/- 3.3 mU/mg prot.), and high ionic strength-soluble (estrous: 18.7 +/- 4.2 and diestrous 12.8 +/- 1.2 mU/mg prot.). 3. Histochemical procedures demonstrated a different distribution for both ChE activities. AChE was found in nerves next to smooth muscle cells of the circular layer and blood vessels, while BChE was concentrated in the longitudinal stratum surrounding the smooth muscle cells. Under the predominance of progesterone, BChE was also found in the endometrial glands. 4. Maximal contractions evoked by the addition of ACh to the isolated organ bath were concentration dependent and greater in estrous than in diestrous. Nevertheless the difference at the two stages of the estrous cycle disappeared when contractions were normalized to smooth muscle cross-sectional area. 5. BChE but not AChE inhibition augmented maximal contractions elicited by ACh in longitudinal but not in circular smooth muscle. 6. The effect of BChE inhibition on the contractile force developed was greater at lower concentrations of ACh and did not depend on the stage of the estrous cycle.

An immunohistochemical study of the catecholamine synthesizing enzymes and neuropeptides in the female guinea-pig uterus and vagina

The uterus and vagina of the guinea pig have been examined, region by region, for acetylcholinesterase, tyrosine hydroxylase, dopamine beta-hydroxylase and aromatic amino acid decarboxylase activity, as well as for the neuropeptides, neuropeptide Y, vasoactive intestinal peptide, substance P, enkephalin and somatostatin. No acetylcholinesterase activity was localized in the uterus, though it was present in associated paracervical ganglion tissues. Of the catecholamine-synthesizing enzymes, tyrosine hydroxylase and dopamine beta-hydroxylase activity was found virtually throughout the reproductive tract, whereas aromatic amino acid decarboxylase activity was restricted in its distribution. Neuropeptide distribution was quite varied. Neuropeptide Y was found throughout the endometrium/submucosa but only in the muscularis of the vagina and not in the myometrium. Substance P was localized in the vagina and uterine horn, though not the body of the uterus. Vasoactive intestinal peptide was present in all regions of the endometrium/submucosa, but not in the myometrium of the uterine horn. Enkephalin and somatostatin were not localized in any part of the reproductive tract examined, apart from paracervical ganglion tissues. The types and significance of the nerves supplying the reproductive tract are discussed.

Autonomic nervous control of cervical secretion in the guinea-pig

Neurogenic influence on cervical secretion was studied in experiments performed on isolated guinea-pig cervix with intact adjacent nerves. The secretion was estimated as carbohydrate efflux. Experiments were undertaken at ovulation time when secretion is most prominent. Hypogastric nerve stimulation significantly increased carbohydrate release. This response was unaffected by phentolamine but inhibited by TTX, scopolamine and hexamethonium, as well as previous destruction of paracervical ganglia. Pelvic nerve stimulation did not affect cervical secretion. Carbachol as well as VIP induced a secretory response of the same extent as did hypogastric nerve stimulation. Scopolamine abolished the VIP-induced secretion. VIP and carbachol in combination had no additive effect. It is concluded that cervical glands of the guinea-pig uterus possess a cholinergic secretomotor innervation. The main pathway is the hypogastric nerve and neurons have a peripheral relay at paracervical ganglia. A more complex peripheral organization cannot be excluded.

Organization of the guinea-pig uterine innervation. Distribution of immunoreactivities for different neuronal markers. Effects of chemical- and pregnancy-induced sympathectomy

The structural organization of the guinea-pig uterine innervation was investigated by an immunofluorescence method using neurofibrillary protein (NF) and neuron-specific enolase (NSE) as general neuronal markers. NF- and NSE-immunoreactive nerve trunks and non-varicose nerves formed continuous networks similar to nerves with analogue morphology and with immunoreactivities for tyrosine hydroxylase (TH; adrenergic nerves) and neuropeptide Y (NPY). NF- and NSE-immunoreactive non-varicose nerves occurred in the myometrium and along vessels, where TH- and NPY-immunoreactive varicose nerves were also comparatively frequent. After chemical sympathectomy all TH- and NPY-immunoreactive varicose nerves and most NF- and NSE-immunoreactive non-varicose nerves disappeared, suggesting colocalization of TH, NPY, NF and NSE immunoreactivities. During pregnancy all NF-, NSE-, TH- and NPY-immunoreactive nerve structures disappeared in the foetus-bearing uterine horns whereas in the cervix and non-foetus-bearing uterine horns only the myometrial TH- and NPY-immunoreactive varicose nerves disappeared. After parturition there was a complete structural restoration of all types of immunoreactive nerves in previously non-foetus-related tissue. The reinnervation of this tissue followed a similar time-course to that after chemical sympathectomy. In contrast, the reinnervation of previously foetus-related tissue was much slower and incomplete. In conclusion, the whole autonomic uterine innervation undergoes overt structural changes during pregnancy and these changes are related to the foetus-bearing regions.

Protein gene product 9.5 (PGP 9.5). A new neuronal marker visualizing the whole uterine innervation and pregnancy-induced and developmental changes in the guinea pig

The guinea pig uterus is supplied by different populations of nerves which can be demonstrated by specific immunocytochemical and histochemical techniques. So far, there has been no single marker displaying entire peripheral innervation patterns. Recently, protein gene product (PGP) 9.5, a cytoplasmic protein in neurons and neuroendocrine cells, was found to visualize both different populations and subtypes of nerves. This prompted the present study of using PGP 9.5 for visualization of the whole uterine innervation. This was performed by the indirect immunofluorescence method using antiserum to PGP 9.5 raised in rabbits. PGP-immunoreactivity was present in all neuronal parts of the extrinsic and intrinsic uterine innervation, including different subpopulations of nerves. This was verified by chemical sympathectomy and sensory denervation with 6-hydroxydopamine and capsaicin-treatment respectively, and double immunostaining. By term a disappearance of uterine PGP-nerve-immunoreactivity was observed which was almost complete in fetus-bearing uterine tissue and further strengthens previous assumptions of a general, pregnancy-induced uterine neuronal degeneration. The developmental time-course and morphology of PGP-immunoreactive nerve structures was similar to that for other neuronal markers and support the suggestion of PGP-immunoreactivity as a general marker for the entire uterine innervation, and suggests that the presence of PGP 9.5-immunoreactivity may coincide with functional maturation of uterine innervation.

S-100-immunoreactive nerves in the guinea-pig uterus with reference to ultrastructural correlations: effects of chemical sympathectomy and pregnancy

In the guinea-pig uterus, by use of an indirect immunofluorescence method, S-100 immunoreactivity was found to be restricted to nerves that corresponded in number, distribution and type to adrenergic axons and pre-terminals. With advancing pregnancy S-100 immunoreactivity completely disappeared in uterine tissue adjacent to a fetus, in parallel with an ultrastructural degeneration of the adrenergic innervation. In the cervix and the uterine horn devoid of a fetus, however, the number and distribution of S-100-immunoreactive nerves was seemingly unchanged and no ultrastructural changes were found in adrenergic nerves. In contrast, chemical sympathectomy produced by 6-hydroxydopamine did not change S-100 immunoreactivity of uterine nerves. These findings suggest that there are differences in the denervation effected by chemical and by pregnancy-induced sympathectomy. The latter probably represents a special type of adrenergic denervation by inducing a degeneration of Schwann cells in addition to destruction of neuronal structures. This may explain the differences in the speed of regeneration of uterine adrenergic nerves following the two types of denervation.

Autonomic nervous control of endometrial secretion in the guinea pig

Secretory responses of the guinea pig endometrium to field stimulation of nerves and/or drugs were studied throughout oestrous cycle. Secretory responses are dependent on the hormonal state of the animals and are seen at oestrus, metoestrus and at implantation time. The cholinergic nature of the secretory innervation was confirmed. Optimal secretory response was found at 0.5 or 1 Hz continuous stimulation. Adrenergic inhibition was revealed at metoestrus (day 3-5), The alpha-adrenergic inhibitory influence had its optimal frequency at 0.5 Hz. The inhibition seemed to be both prejunctional and postjunctional. VIP increased endometrial secretion, the effect was probably preterminal. Burst stimulation at any frequency gave less (or no) secretory responses under these experimental conditions. The complex organization of the endometrial innervation is apparent.

Cholinergic nerves in mouse uterus

The topographical distribution of cholinergic nerve fibres in the uterus was studied in normal as well as chemically sympathectomized mice. Our analysis was performed using both transverse sections and whole mounts, in order to analyse the distribution of cholinergic nerves within the various layers of the uterus and to study the morphology of nerve plexuses that supply the organ. Cholinergic nerve fibres were found chiefly around the uterine artery and its primary ramifications. Nerve fibres coming from arterial plexuses are distributed to the myometrium and more infrequently to the endometrium. Groups of acetylcholinesterase positive ganglion cells were located in the cervix. The distribution pattern of the cholinergic innervation of mouse uterus shows important topographical differences. In the tubal end of uterine horn the innervation is poor and cholinergic nerve fibres are organized in a sparse plexus. The number and the density of uterine nerves increase gradually proceeding toward the cervix. The cervix shows the richest innervation. The findings that observed nerve fibres are unaltered by chemical sympathectomy and are revealed using short incubation times suggest their parasympathetic nature.

Endometrial cholinergic secretory responses during estrous cycle, pregnancy and after estrogen and/or progesterone treatment of the guinea-pig

During estrous cycle as well as during pregnancy and after treatment with estrogen and/or progesterone uterine mucus secretory responses were studied as amount of carbohydrate released from everted guinea-pig uteri after transmural nerve stimulation of carbachol administration. In estrous cycle both stimuli increased secretion by about 20% except for the late diestrus phase, when no secretory responses were seen. In pregnancy a secretory response was noted at implantation time. From mid pregnancy and onwards secretory responses of increasing magnitude were obtained. Secretory responses persisted post partum. Evidence of an adrenergic inhibitory influence on the neurogenic cholinergic responses during metestrus was noted. Both stimuli increased carbohydrate release by about 50% above resting level in uteri from animals receiving combined hormone treatment. In uteri of animals receiving estrogen only the increase was about 20%. No definite secretory response was obtained in uteri from animals receiving progesterone only. It is suggested that both hormones are necessary for full cholinergic secretory response to nerve stimulation or muscarinic drugs. It is concluded that muscarinic stimulation of the endometrium results in mucus secretion during all crucial events during the reproductive cycle. Furthermore a cholinergic secretory innervation seems to be present at all these times.