Gray-scale and color Doppler ultrasound characteristics of endometrial cancer in relation to stage, grade and tumor size

OBJECTIVES

To describe the gray-scale and vascular characteristics of endometrial cancer in relation to stage, grade and size using two-dimensional (2D)/three-dimensional (3D) transvaginal ultrasound.

METHODS

This was a prospective multicenter study including 144 women with endometrial cancer undergoing transvaginal ultrasound before surgery. The sonographic characteristics assessed were echogenicity, endometrial/myometrial border, fibroids, vascular pattern, color score and tumor/uterus anteroposterior (AP) ratio. Histological assessment of tumor stage, grade, type and growth pattern was performed.

RESULTS

Hyperechoic or isoechoic tumors were more often seen in Stage IA cancer, whereas mixed or hypoechoic tumors were more often found in cancers of Stage IB or greater (P = 0.003). Hyperechogenicity was more common in Grade 1-2 tumors (i.e. well or moderately differentiated) (P = 0.02) and in tumors with a tumor/uterine AP ratio of < 50% (P = 0.002), whereas a non-hyperechoic appearance was more commonly found in Grade 3 tumors (i.e. poorly differentiated) and in tumors with a tumor/uterine AP ratio of ≥ 50%. Multiple global vessels were more often seen in tumors of Stage IB or greater than in Stage IA tumors (P = 0.02), in Grade 3 tumors than in Grade 1 and 2 tumors (P = 0.02) and in tumors with a tumor/uterine AP ratio of ≥ 50% (P < 0.001). A moderate/high color score was significantly more common in tumors of higher stage (P = 0.03) and larger size (P = 0.001).

CONCLUSION

The sonographic appearance of endometrial cancer is significantly associated with tumor stage, grade and size. More advanced tumors often have a mixed/hypoechoic echogenicity, a higher color score and multiple globally entering vessels, whereas less advanced tumors are more often hyperechoic and have no or a low color score.

Sonographic characteristics of squamous cell cancer and adenocarcinoma of the uterine cervix

OBJECTIVE

The objective of this study was to describe the sonographic characteristics of squamous cell cancer (SCC) and adenocarcinoma (AC) of the cervix using transvaginal ultrasound.

METHODS

Women with early stage cervical cancer undergoing transvaginal ultrasound examination before surgery were prospectively included. The sonographic characteristics were assessed with regard to tumor morphology, vascularization, size, extension and location. Histological assessment of tumor subtype, size, growth pattern, extension and location was performed. Both sonographic and histological assessments were carried out according to a standardized protocol.

RESULTS

Fifty-five women were recruited. Ten were excluded because no tumor was seen on ultrasound examination and five were excluded because radical surgery was aborted as a result of positive lymph nodes, detected using the sentinel node technique. Among the remaining 40 women, 20 had AC and 20 had SCC. At pathological examination, 34 women had tumors confined to the cervix, three had parametrial invasion and three had vaginal invasion. Hypoechogenicity was associated with SCC in 73% (11/15) of the women, while isoechogenicity indicated AC in 68% (13/19) of the women (P = 0.03). Mixed echogenicity (n = 4) showed a non-significant association with larger tumor volume (P = 0.23). Hyperechogenicity was found in two women, both of whom had the less malignant villoglandular AC. Color Doppler signals were found in all cases of AC and in 90% (18/20) of cases of SCC, compared with most normal cervical tissue in which virtually no detectable vascularization was found.

CONCLUSION

We found that the sonographic appearance of SCC and AC differs. This knowledge should be useful in the clinical evaluation of cervical tumors.

Combretastatin A-1 phosphate potentiates the antitumor activity of carboplatin and paclitaxel in a severe combined immunodeficiency disease (SCID) mouse model of human ovarian carcinoma

In search for new therapeutic modalities to target epithelial ovarian carcinomas, we investigated the effect of the antiangiogenic drug combretastatin A-1 phosphate (CA1P) as a single treatment or in combination with established therapy, ie, carboplatin and paclitaxel. Five different human epithelial ovarian carcinoma cell lines were inoculated subcutaneously into FOX CHASE CB-77 severe combined immunodeficiency disease (SCID) mice. When tumors reached a volume of approximately 100 mm(3), the treatment was initiated. All drugs were given intraperitoneally at weekly doses. CA1P was more effective as an antitumor agent than combretastatin A-4 phosphate as a single-drug treatment or in combination with carboplatin and paclitaxel. CA1P had a strong tumor outgrowth inhibiting effect on four out of five tumors included in this study. Comparing animals receiving CA1P with animals receiving a combination of carboplatin and paclitaxel, CA1P was more effective on two out of three tested tumors, whereas carboplatin and paclitaxel were more effective on one out of three of the tumors. We show that treatment of human ovarian carcinomas with CA1P in the SCID mouse model results in a strong antitumor effect both as a single-drug treatment and as an enhancement of the therapeutic effect in a combination treatment protocol with carboplatin and paclitaxel.

Effects of vasoactive intestinal polypeptide (VIP) on the neuromuscular complex in the bovine ovarian follicle wall

1. When stimulating the local nerves in the bovine ovarian follicle wall preparation (4 Hz, 1 ms pulse duration and 7.5 V between the electrodes) vasoactive intestinal polypeptide reduced the neurogenic contraction and at the highest concentration tested (3 x 10(-7) M) almost abolished the response. Peptide histidine isoleucine only slightly reduced the contraction. 2. Strips from the follicle wall of bovine ovaries were incubated in Krebs-Ringer solution containing [3H]-noradrenaline for measurement of transmitter liberation during electrical field stimulation (5 Hz frequency, 1 ms pulse duration, 10 V between the electrodes). Vasoactive intestinal polypeptide had no effect on the electrically induced efflux of radioactivity. 3. Vasoactive intestinal polypeptide and its related peptide, peptide histidine isoleucine, relaxed precontracted follicle strips dose dependently with I(max) at 3 x 10(-7) M of 60% and 40% respectively. 4. Vasoactive intestinal polypeptide 10(-7) M did not alter the EC50 value of the noradrenaline-(10(-9)-10(-4) M) or carbachol-induced (10(-8)-3 x 10(-4) M) contraction in the follicle strips, but significantly reduced the E(max) value of the noradrenaline but not the carbochol-mediated contraction. 5. These results suggests that vasoactive intestinal polypeptide, and to some extent peptide histidine isoleucine, have a postjunctional role in ovarian follicle contractility and might further interfere with the ovulatory process.

The influence of neuropeptide Y and norepinephrine on ovulation in the rat ovary

Neuropeptide Y (NPY) was measured in tissue extracts from ovaries of rats treated with pregnant mare serum gonadotropin (PMSG). The extracted NPY-immunoreactive material was identical to synthetic human NPY with regard to size and hydrophobicity as evaluated by gel filtration and high performance liquid chromatography. The concentration of NPY was related to the estrous cycle and a maximum was observed in relation to the endogenous luteinizing hormone (LH) peak. NPY immunoreactivity was demonstrated by immunohistochemistry to be localized within nerve fibers supplying blood vessels and follicles. The increase in the NPY content could not be related to accumulation around specific ovarian structures. Employing an in vitro set-up, NPY (10(-7) M) was unable to induce ovulation and did not increase the ovulation rate in LH-stimulated ovaries. The combination of NPY (10(-7) M) and NE (10(-7) M) did not significantly increase the number of ovulations compared to that induced by NE (10(-7) M) alone. In conclusion, NPY content in the ovary is related to the estrous cycle, but NPY does not seem to have any direct effect on the ovulatory process.

Vasoactive intestinal polypeptide in the PMSG-primed immature rat ovary and its effect on ovulation in the isolated rat ovary perfused in vitro

The immature rat ovary contains VIP immunoreactive nerve fibres sparsely distributed around blood vessels, in the interstitial gland and around follicles. The VIP concentration, measured radioimmunologically, decreased significantly after PMSG treatment (10 i.u.), probably due to ovarian enlargement and oedema, while the total VIP content (total of 0.12 pmol in both ovaries) did not change after PMSG priming. The ovulatory effect of VIP was studied using in-vitro perfused ovaries from immature 28-day-old rats primed with 10 i.u. PMSG. In all ovaries perfused, VIP (10(-7) M) induced ovulations with a rate of 2.33 +/- 0.56. The ovulation rate was significantly lower than that of ovaries stimulated by LH (0.1 microgram/ml) (5.20 +/- 0.86 ovulations per ovary). No synergistic effect on the ovulation rate was seen when LH and VIP were administered together (5.20 +/- 0.49 ovulations per ovary). The results suggest that the neuropeptide VIP may represent one of the local factors involved in the ovulation process.

Immunocytochemical demonstration of contractile cells in the human ovarian follicle

Actin- and myosin-like immunoreactivity is found in cells located in the theca externa of the follicle wall of the human ovary, and corresponding to previously observed myoid cells. The immunocytochemical observation provides direct structural evidence that non-vascular contractile cells are also present in the follicle wall in humans. As expected, perifollicular blood vessels showed a positive immunoreaction for actin and myosin in their smooth muscle walls.

The neuropeptides vasoactive intestinal polypeptide, peptide histidine isoleucine and neuropeptide Y modulate [3H]noradrenaline release from sympathetic nerves in the choroid plexus

The neurotransmitter peptides vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine (PHI) and neuropeptide Y (NPY) are located in nerve fibers supplying the pig choroid plexus, which receives an abundant sympathetic innervation. We characterized the release of [3H]noradrenaline ([3H]NA) from this tissue elicited by electrical field stimulation and studied the effects of the above-mentioned peptides on this release. The release of [3H]NA was found to be almost exclusively of neurogenic origin, despite there being a marked non-neuronal uptake of [3H]NA into the epithelium of the choroid plexus. NPY significantly decreased the release of [3H]NA by approximately 10% while VIP and PHI enhanced release by up to 25 and 35%, respectively, indicating a possible synergistic role of the two latter peptides and NA in the choroid plexus.

Histaminergic effects on the isolated rat ovarian artery during the estrous cycle

Histamine may play a role in many of the events occurring in the ovarian tissue and leading to ovulation. To elucidate the histaminergic influence on the ovarian vasculature, the mechanical response of the isolated rat ovarian artery to histamine and histamine agonists was investigated. Histamine relaxed the precontracted vessel segments in a concentration-dependent way, amounting to 82.7 +/- 4.3% of the papaverine-induced relaxation. This relaxant effect was counteracted by both the H1 antagonist, pyrilamine, and the H2 antagonist, cimetidine. That the effect of histamine was mediated by both histamine receptor subtypes was further confirmed by the relaxant effect produced in the presence of either of the H1-specific agonists, 2-pyridylethylamine and 2-methylhistamine on the one hand, and the H2-specific agonists, impromidine and 4-methylhistamine on the other. The H1 receptor-induced relaxation was mediated via an effect on the endothelium, whereas the H2 receptor-mediated relaxation was mostly a direct effect on the smooth musculature in the vessel wall. No major differences in the mechanical response of the rat ovarian artery were seen during the different stages of the estrous cycle, although at late proestrus, just before ovulation, the maximum relaxation induced by histamine was particularly high, in spite of a low sensitivity of the receptors for the amine.

Prejunctional alpha 2-adrenoreceptors modulate the stimulated release of noradrenaline in isolated follicle strips from bovine ovaries

1. Strips from the follicle wall of bovine ovaries were incubated in Krebs-Ringer solution containing 3H-noradrenaline for measurement of transmitter liberation during electrical field stimulation (5 Hz frequency, 1 ms pulse duration, 10 V between the electrodes). The effects of noradrenaline as well as selective alpha-adrenoreceptor agonists and antagonists were studied on the electrically induced efflux of radioactivity. 2. Noradrenaline (1 microM) inhibited the stimulated release of radioactivity. The alpha 2-adrenoreceptor agonist, oxymetazoline, significantly reduced the release of radioactivity in concentrations as low as 0.01 microM. The alpha 1-adrenoreceptor agonist, phenylephrine (0.01-1 microM), was without significant effect. 3. Phentolamine (0.01-1 microM) and the selective alpha 2-adrenoreceptor antagonist, idazoxan (0.01-1 microM) significantly enhanced the electrically evoked release. The alpha 1-adrenoreceptor antagonist, prazosin (0.01-1 microM), was without effect. Idazoxan (0.1 microM) reversed the inhibitory effect of oxymetazoline (0.1 microM). 4. It is concluded that administration of noradrenaline or the alpha 2-adrenoreceptor agonists reduces the release of labelled noradrenaline by acting on prejunctional alpha 2-adrenoreceptors in the noradrenergic nerves distributed in the wall of the bovine ovarian follicle. This is one of several prejunctional receptor mechanisms that modulate the activity of the sympathetic nerves innervating the smooth musculature of the follicle wall.

Serotonin uptake into cerebrovascular nerve fibers of rat, visualization by immunohistochemistry, disappearance following sympathectomy, and release during electrical stimulation

Immunohistochemistry as well as in vitro uptake and release of [3H]5-HT were performed on pial arteries of rat to investigate the nature of 5-HT containing nerve fibers. Immunoreactive fibers were constantly found only in the basilar, vertebral and superior cerebellar arteries, while in the other parts of the circle of Willis, 5-HT immunofluorescent fibers were absent. After systemic treatment with tryptophan following inhibition of monoamine oxidase with nialamide the immunofluorescence intensity was markedly enhanced. The 5-HT immunoreactive fibers disappeared after superior cervical ganglionectomy or intraventricular administration of 6-hydroxydopamine, but persisted after administration of 5,6-dihydroxytryptamine. When isolated vessels were incubated in low concentration of 5-HT (1 nM) together with nialamide, a very dense plexus of 5-HT immunoreactive fibers appeared in all branches of the circle of Willis. Uptake and release experiments were carried out by incubation of arterial preparations with 3 nM [3H]5-HT (together with nialamide), followed by electrical field stimulation, or by exposure to tyramine or 124 mM potassium, all of which induced a 100%-350% increase in the tritium release over prestimulation values. Preincubation with cocaine and bilateral superior cervical ganglionectomy abolished or markedly attenuated the release upon all modes of stimulation. The results suggested that the 5-HT observed by immunohistochemistry in pial arteries is located in sympathetic nerve terminals where it may serve as a neuromodulator that is released during nerve activation.

A heterogeneous population of alpha 1-adrenoceptors mediates contraction of the isolated follicle wall from the bovine ovary

Strips from Graafian follicles of bovine ovaries were tested for their contractile response in vitro in order to characterize the type of post-junctional alpha-adrenoceptor involved. Electrically induced contractions were inhibited concentration-dependently by the alpha 1-antagonist, prazosin. Besides noradrenaline the alpha 1-selective agonists, methoxamine and phenylephrine, caused the strips to contract, whereas the alpha 2-selective agonists clonidine, oxymetazoline and B-HT920 were without effect. However, the alpha 1-selective antagonist prazosin gave a line with a slope less than unity in the Schild plots with noradrenaline and methoxamine. From results obtained with or without the presence of two classes of neuronal uptake blockers (desipramine and cocaine) it is concluded that the post-junctional alpha 1-receptor population is inhomogeneous. The regular appearance of the Schild plot obtained with phenylephrine may be due to involvement also of a component of noradrenaline release by this agonist. The pA2 value in the test with phenylephrine was 9.27, with a corresponding kB of 3.81 +/- 1.15 X 10(-10) M.

Is serotonin involved in the ovulatory process of the rat ovary perfused in vitro?

The presence of 5-HT (serotonin) in ovarian tissue and its varying concentrations during the oestrous cycle suggests that it takes part in ovarian function and in the ovulatory process as one of several mediators of the inflammatory-type reaction preceding follicular rupture. With the aid of a recirculating perfusion model, in which the central stimulatory action of 5-HT was avoided, its direct ovarian effect on ovulation was studied using immature, pregnant, mare serum gonadotrophin (PMSG)-treated rats. Four out of five ovaries ovulated after the addition of 5-HT to the perfusion medium, though the ovulation rate (0.8 per ovary) did not reach the order of magnitude seen after luteinizing hormone (LH) stimulation (5.4 per ovary). The selective 5-HT2 receptor antagonist, ketanserin, did not significantly reduce the 5-HT induced ovulations, and moreover, reduced the LH-stimulated ovulations. The calcium entry blocker, nifedipine, had no effect on either 5-HT or LH induction ovulations.

Extracellular and intracellular calcium sources mediating contractile responses of smooth muscle in bovine ovarian follicle and ovarian artery

The relative importance of extracellular and intracellular calcium sources mediating smooth muscle contraction in ovarian follicle and ovarian artery was assessed in experiments on the influence of nifedipine, D-600, amrinone, diethylstilbestrol (DES), lanthanum and/or calcium removal on contractions induced by K+ depolarization, by noradrenaline, histamine and acetylcholine. The K+-induced response was biphasic in the ovarian artery but not in the ovarian follicle. The K+-induced contraction in both preparations was greatly inhibited by nifedipine (1 microM), D-600 (10 microM) and lanthanum (2 mM). Although both phases of the responses in the ovarian artery appeared to be completely dependent on extracellular calcium, phase I was significantly more sensitive to nifedipine than phase II. Incubation in calcium-free medium for 15 min almost abolished the K+-induced contraction. Noradrenaline- and histamine-induced contractions of ovarian follicle were essentially unaffected by nifedipine (1 microM) and D-600 (10 microM) whereas the noradrenaline-induced contraction in ovarian artery was inhibited significantly by D-600 (1 and 10 microM) but not nifedipine (1 microM). In calcium-free medium containing EGTA (1 mM) the responses of ovarian follicle to noradrenaline and histamine were reduced by 26 and 22% respectively. When preparations were stimulated with noradrenaline more than one in calcium-free medium, the contraction decreased progressively compared to time-matched controls. The response was 34% of the control after 50 min in calcium-free medium containing EGTA. In the ovarian artery the response obtained (6% of control) was significantly smaller (P less than 0.05) than that in the follicle.(ABSTRACT TRUNCATED AT 250 WORDS)

GABA suppresses stimulation-induced release of [3H]-noradrenaline from sympathetic nerve fibres in bovine ovarian follicles

1 Strips from the bovine ovarian follicle wall were incubated in Krebs-Ringer solution containing [3H]-noradrenaline in order to saturate sympathetic nerve fibres with radiolabelled transmitter. This allowed the study of field stimulation-evoked transmitter release. 80.3 +/- 3.9% of the tritium released upon stimulation (10 Hz, pulse duration 1 ms, 10 V between the electrodes) was noradrenaline. 2 The stimulated release of tritium was totally blocked in calcium-free, EGTA (1 mM) containing medium or by 1 microM tetrodotoxin. Chemical sympathectomy (6-hydroxydopamine treatment) in vitro reduced the tritium content of the strip by 85%. The neuronal amine uptake blocker desipramine (0.6 microM) was almost equally effective in inhibiting the incorporation of tritium. The extraneuronal amine uptake blocker normetanephrine (10 microM) reduced the tritium content by 30%. Together, the results suggest that the electrically evoked release of tritium reflects the release of [3H]-noradrenaline from sympathetic nerve fibres. 3 gamma-Aminobutyric acid (GABA) concentration-dependently reduced the electrically evoked tritium release. Also the GABAB-receptor agonist baclofen (30 microM) reduced the stimulated tritium release whereas muscimol (100 microM), a GABAA-receptor agonist, failed to affect the release. 4 The selective GABAA-receptor antagonist bicuculline (3 and 100 microM) did not block the effect of GABA, while 3-amino-1-propanesulphonic acid (3-APA), a blocker of GABAB-receptors reversed the inhibitory effect of GABA. The results suggest that neuronal GABAB-receptors are involved in the GABA-evoked suppression of stimulated noradrenaline release.

Characterization of presynaptic 5-HT receptors on adrenergic nerves supplying the bovine ovarian follicle

1. The effects of 5-hydroxytryptamine (5-HT) on contraction and release of [3H]-noradrenaline were investigated in vitro in bovine ovarian follicle strips. Using available selective agonists and antagonists, an effort was made to characterize the type of receptor mediating the inhibitory effect of 5-HT on neurogenic contraction and release of [3H]-noradrenaline by electrical field stimulation. 2. 5-Hydroxytryptamine inhibited the neurogenic contraction and release of [3H]-noradrenaline evoked by electrical field stimulation in a concentration-dependent manner. Like 5-HT, 5-carboxamidotryptamine (5-CT) and methysergide reduced the transmitter release as well as the neurogenic contraction, whereas 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) failed to inhibit both responses in concentrations up to 0.1 microM. 3. The 5-HT (1 microM)-induced inhibition of contractile responses was more evident during stimulation at low frequencies (4 and 8 Hz) than during high frequency electrical stimulation (16 and 32 Hz). 4. Methiothepin (1 microM) and methysergide (10 microM) significantly antagonized the inhibitory effect of 5-HT on the electrically evoked release of tritium, whereas cyanopindolol, MDL 72222 and ketanserin (all 0.1 microM) were without effect. In addition, ketanserin, MDL 72222, cimetidine, pyrilamine, atropine, propranolol and indomethacin were without effect on the 5-HT-induced inhibition of the neurogenic contraction. 5. It is suggested that 5-HT inhibits the electrically evoked transmitter release from adrenergic nerves in the bovine ovarian follicle wall via prejunctional 5-HT1-like receptors. This was based on the findings that 5-CT was a potent agonist, methiothepin an antagonist and the lack of effect of MDL 72222, cyanopindolol and ketanserin.

Characterization of histamine receptors mediating contraction and relaxation of the ovarian follicle wall

Histamine is known to be present in ovarian tissue and may play a role in the ovulation process. The effect of histamine on the follicular smooth musculature was investigated using strips from the protruding part of mature bovine follicles, mounted in vitro for registration of isometric motor activity. Histamine contracted the preparation in a concentration-dependent manner. The response was inhibited competitively by the specific H1 receptor antagonist pyrilamine while the adrenergic alpha-receptor antagonist phentolamine had no clear-cut effect. A Schild plot revealed a pA2 value of 8.81, corresponding to a mean KB value (dissociation constant for receptor-antagonist complex) of (7.5 +/- 3.2) X 10(-9) M. After potassium depolarization and blockade of the contractile H1-receptors with pyrilamine, histamine induced a concentration-dependent relaxation of the follicle wall preparation. This response could be inhibited by the H2-receptor antagonist cimetidine (which also potentiated the contractile effect in the absence of pyrilamine). The pA2 value for the cimetidine-induced inhibition was 6.25, and KB was found to be (6.5 +/- 3.0) X 10(-7) M. The beta-receptor antagonist propranolol was effective only in very high concentrations. It is suggested that a possible role for histamine during follicle rupture is mediated via specific receptors in the follicular smooth musculature.

Histamine stimulates progesterone synthesis and cyclic adenosine 3',5'-monophosphate accumulation in isolated preovulatory rat follicles

The effect of histamine on progesterone synthesis and cyclic adenosine 3',5'-monophosphate (cAMP) accumulation was studied in superfused and incubated follicles dissected free from immature rats treated with pregnant mare serum gonadotrophin (PMSG). Histamine, like LH, increased the progesterone synthesis, but to a smaller extent. The H2-antagonist, cimetidine, inhibited completely the histamine-induced progesterone increase while the H1-antagonist, pyrilamine, as well as propranolol and atropine did not affect the initial response but modified its duration. The specific H2-agonist, 4-methylhistamine, but not the H1-agonist, 2-methylhistamine, mimicked the effect of histamine on progesterone synthesis. In the presence of the phosphodiesterase inhibitor, IBMX, histamine increased tissue levels of cAMP. These results suggest that histamine stimulates progesterone synthesis via the H2-receptor with cAMP acting as secondary intracellular messenger.

Alteration by histamine of the sympathetic nerve-mediated contractions in the bovine ovarian follicle wall in vitro

The histaminergic effect on electrically induced contractions and tritium release was studied in vitro, using strips from the wall of mature bovine ovarian follicles. Follicular fluid and blood plasma from the animals were analysed for electrolyte, bicarbonate, glucose and total protein concentrations in order to compare them with the concentrations of these components in the Krebs-Ringer solution used in the experiments. Electrical field stimulation (EFS) of the follicle strip caused a contraction which was completely blocked by tetrodotoxin and was predominantly of adrenergic origin since phentolamine, in contrast to atropine, blocked the response. The neurogenic response was inhibited by histamine in a concentration-dependent way via the H1-receptor since the H1-antagonist, pyrilamine, counteracted the inhibitory effect of histamine while the H2-antagonist, cimetidine, potentiated the effect. This histaminergic response of EFS-induced contractions could be reproduced in experiments where the H1-agonist, 2-methylhistamine, was inhibitory while the H2-agonist, 4-methylhistamine, had no obvious influence on the twitch response. Histamine reduced the contractile response to exogenous noradrenaline via the H1-receptor, because pyrilamine counteracted, and cimetidine potentiated the effect. The histamine-induced depression of the motor response to EFS and exogenous noradrenaline was probably due to a postjunctional effect mediated by the H1-receptor. Experiments utilizing [3H]noradrenaline release during EFS did not suggest prejunctional effects of histamine. Chemical determinations on follicle fluid and plasma showed that the artificial follicular fluid imitated well the environmental conditions the follicle wall is exposed to in situ.

Evidence for prejunctional GABAB receptors mediating inhibition of ovarian follicle contraction induced by nerve stimulation

The motor effects of gamma-aminobutyric acid (GABA) on the bovine ovarian follicle were studied in vitro using strips from follicle walls. Electrical field stimulation of nerves in the preparation, secured by tetrodotoxin blockade, caused a contraction that was almost totally abolished by phentolamine and only slightly affected by atropine. This mainly adrenergic neurogenic response was inhibited by GABA in a dose-dependent way. The GABAA-receptor antagonists, bicuculline and picrotoxin, did not affect the GABA action whereas the GABAB-receptor antagonist, homotaurine, significantly inhibited the GABA effect. The GABAA-receptor agonist, muscimol, did not affect the contractile response while the GABAB-receptor agonist, baclofen, imitated the action of GABA. On the other hand, GABA had no direct contractile or relaxing effect on the follicle strips nor did it interfere with the contractile response induced by noradrenaline or acetylcholine. The findings suggest that activation of prejunctional GABAB receptors inhibits transmitter release from mainly adrenergic nerves associated with the follicle, thereby affecting nerve-mediated tension in the follicle wall.

Existence and coexistence of peptides in nerves of the mammalian ovary and oviduct demonstrated by immunocytochemistry

The immunocytochemical distribution of substance P (SP), gastrin releasing peptide (GRP), vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine (PHI), and neuropeptide Y (NPY) was studied in the ovary and the Fallopian tube (oviduct) of rats, guinea-pigs, cows, pigs and humans. Generally, the nerve supply was better developed in the oviduct than in the ovary. GRP fibers were most scarce in all tissues. Nerves containing SP were particularly numerous in the oviduct of rat and guinea-pig, supplying the muscular wall and blood vessels. VIP and PHI coexisted in dense plexuses of nerves, not only around blood vessels but also in the follicular wall and the interstitial gland of the ovary, as well as within the smooth muscle layers and subepithelially in the oviduct. The general distribution of NPY was similar, but these immunoreactive nerves were even more numerous. Sequential staining for dopamine-beta-hydroxylase and NPY together with results of chemical sympathectomy with 6-hydroxydopamine suggested that NPY was stored in the noradrenergic sympathetic nerves.

Involvement of local adrenergic receptors in the process of ovulation in gonadotrophin-primed immature rats

Immature female rats were primed with 4 i.u. PMSG at 08:00 h of Day 26. This results in ovulation in the morning of Day 29. The number of ovulations was counted in terms of newly formed corpora lutea in the morning of Day 30. Various adrenergic drugs were delivered into the ovarian bursa bilaterally in the afternoon of Day 27 to study their effect on ovulation. A methyl cellulose gel solution was used as vehicle to minimize leakage from the bursa. Noradrenaline, terbutaline and 4-aminopyridine significantly enhanced the number of corpora lutea compared to control ovaries injected with gel vehicle alone. The effect of terbutaline was counteracted by propranolol. Phentolamine partly blocked the noradrenaline-induced enhancement and the antagonist alone significantly reduced the number of ovulations. The results indicate that stimulation of alpha-adrenergic receptors (probably via actions in the follicle wall) as well as beta-receptors (influencing steroid-producing cells) may interfere with the ovulation process.

Histochemistry and ultrastructure of adrenergic and acetylcholinesterase-containing nerves supplying follicles and endocrine cells in the guinea-pig ovary

The autonomic nerve supply of the guinea-pig ovary was investigated by a combination of light- and electron microscopy. At the light-microscopic level, adrenergic fibres were identified due to their formaldehyde-induced fluorescence. In addition, the ovary contained acetylcholinesterase-positive fibres. In all parts of the ovary, the adrenergic fibres were most numerous. At the ultrastructural level it was possible to identify the adrenergic nerve terminals with the aid of the false adrenergic transmitter, 5-hydroxy-dopamine. Thus, large numbers of adrenergic terminals, characterized by their content of 50-60 nm, electron-dense synaptic vesicles, were seen within the interstitial gland, where they formed close contacts with the endocrine cells (membrane-to-membrane distance, 20-100 nm). The follicular theca externa was also richly supplied by adrenergic nerves. At this location, close contacts (50-100 nm) were identified between the nerve terminals and the smooth muscle-like cells. Very few adrenergic nerve fibres were present in the theca interna of follicles or in the corpus luteum. Non-adrenergic nerve terminals, characterized by electron-lucent synaptic vesicles of 50-60 nm diameter, were observed together with the adrenergic fibres. They were always present in much lower numbers than the latter. No "p-type" nerves were identified by electron microscopy.

Intraovarian adrenergic nerves in the guinea-pig: development from fetal life to sexual maturity

The development of the intraovarian adrenergic nervous system was investigated in the guinea-pig by use of chemical determination of catecholamines with high performance liquid chromatography (HPLC) and with the formaldehyde-induced fluorescence method for visualization of adrenergic nerves (Falck-Hillarp technique). Ovaries from fetuses (39-40, 45-50, 55-57, 60-63 days of gestation) and young animals (1, 2, 3, 7, 14, 30, 40-45 days of age) were included in the study. The noradrenaline concentration was low in the ovaries from the youngest fetuses but increased with age, reaching a maximum level at 2 days post partum. A marked decrease in noradrenaline concentration from the second to the third day of life was found as a consequence of the rapid increase in the ovarian weight during this time. A similar decrease in ovarian noradrenaline concentration after a period of rapid ovarian growth was noted at 30 days of age. Measurable amounts of adrenaline were found in the ovary only in the fetal stages; the highest concentration (0.73 microgram) was detected at 55-57 days of gestation.