Most of the fibres that constitute the superior ovarian nerve (SON) originate at the neuronal bodies of the coeliac ganglion and innervate rat ovarian stroma cells. The purpose of this work was to study the part played by innervation on ovarian release of progesterone on day 15 and at the end of pregnancy in an integrated in vitro system known as the coeliac ganglion-SON-ovary system.We also investigated, in the same system, whether there is some kind of inter-relationship between the effect of adrenergic agents and LH on progesterone release on day 15 of pregnancy.The coeliac ganglion and the ovary were incubated in separate compartments, linked by the SON. The ovary was immersed in 2 ml buffer solution (ovarian compartment) and the coeliac ganglion was immersed in 2 ml of a different buffer solution (ganglion compartment). Under these conditions, the accumulation of progesterone in the ovarian compartment medium was used as an endpoint. Conditions were standardised on day 15 of pregnancy, when the decrease in the release of ovarian progesterone caused by non-specific stimulation on the ganglion with KCl (56 mM) demonstrated the functional integrity of the system. Neural influence was evaluated by the addition of adrenergic agents at a concentration of 10 6 M to the coeliac ganglion. On day 15 of pregnancy, noradrenaline and propranolol increased progesterone release while phentolamine diminished it. The existence of ganglionic tone was assessed by analysing progesterone basal levels at different stages of pregnancy. The highest secretion of progesterone was found to take place on day 15, diminishing as pregnancy advanced. In addition, adrenergic neural participation was studied during the physiological luteolysis occurring at the end of pregnancy. Major findings were that noradrenaline increased ovarian accumulation of progesterone on day 19 and decreased it on day 20, while propranolol and phentolamine diminished progesterone release on both days. In additional studies, some neuroendocrine aspects were investigated at a peripheral level. The addition of LH only to the ovarian compartment did not affect progesterone secretion. However, when LH in the ovarian compartment was accompanied by noradrenaline, propranolol or phentolamine in the ganglion compartment, the release of progesterone decreased.It can be concluded that modifications of the neural state of the coeliac ganglion affect ovarian progesterone secretion and the physiology of pregnancy via the SON. The results may confirm that the coeliac ganglion-SONovary system provides a direct link between the autonomic nervous system and physiological events during pregnancy.
The axons that constitute the ovarian nervous plexus originate mostly in the principal neurons of the superior mesenteric ganglion (SMG) that is part of the sympathetic ganglionic chain and exhibits cholinergic receptors. In order to observe the effect of acetylcholine, the main neurotransmitter in the ganglionic transmission, the purpose of the present work was: first, to standardize an integrated ex vivo superior mesenteric ganglion-ovarian nervous plexus-ovary (SMG-ONP-O) system in oestrus day rats; secondly, to determine if the ganglionic cholinergic stimulus modifies the release of nitric oxide and steroids in the ovary compartment in the absence of humoral factors; and thirdly, to investigate if there are differences in the responses between the left and right ovaries caused by the neural stimulus. The ex vivo experimental left and right systems were developed and standardized. The systems were incubated in Krebs-Ringer phosphate buffer in a Dubnoff metabolic shaker. The progesterone release was determined to standardize the incubation times, obtaining different responses between the left and right systems, which shows that both systems have their own autonomic tone. Non-specific stimulation with KCl in the ganglion compartment provoked different responses in terms of release of progesterone and oestradiol. Progesterone decreased in the left and right systems.However, oestradiol diminished at short times and increased at 60 and 120 min in the left ovary, whereas it increases at 30 and 60 min in the right ovary. These different responses show the sensitivity and viability of both systems. When acetylcholine was used in the ganglion compartment, the release of nitric oxide, progesterone, androstenedione and oestradiol was evaluated. The liberation of nitrite increased at 15, 30 and 60 min in the left system and decreased in the right system at 120 min. Progesterone showed a decrease in its release at 15, 30 and 120 min and androstenedione at 15 min in the left ovary compartment. In the right ovary, only progesterone decreased in relation to the control at 120 min while androstenedione did not show significant changes. Oestradiol showed an increase in the left ovary compartment at all the studied times, while in the right ovary it did not show any changes. These results indicate that the neural stimulus from the superior mesenteric ganglion through the ovarian nervous plexus is one of the factors modulating the secretory activity of the ovarian steroids and nitric oxide. The system is viable and also shows a different sensitivity of the left ovary in relation to the right one at least in this cycle stage, characterized by marked irrigation and profound structural changes in the ovary.
Using the ex vivo coeliac ganglion-superior ovarian nerve-ovary system at the end of pregnancy when luteal regression starts, we investigated whether, when administered systemically or when added directly to the ganglion compartment, androstenedione (A 2 ) can reverse such regression, and whether the neural (noradrenaline (NA)) and endocrine (A 2 ) joint action modifies the release of ovarian progesterone. The experimental groups were as follows: group 1 -A 2 injected systemically 48 h before incubation of the system (A 2 ) s ; group 2 -A 2 directly added to the ganglion compartment (A 2 ) g ; group 3 -A 2 injected 48 h before incubation of the system with NA in the ganglion compartment (A 2 1 NA); group 4 -A 2 plus NA added to the ganglion compartment (NA 1 A 2 ) g . The controls were ex vivo systems without treatment (control), and with the addition of NA alone in the ganglion compartment (NA). The results were as follows. For (A 2 ) s versus control, progesterone increased on days 19 and 21 of pregnancy at all the studied times and only at 180 min on day 20. For (A 2 1 NA) versus (A 2 ) s , progesterone increased on days 19 and 21. For (A 2 1 NA) versus NA, progesterone increased at all the studied times on days 19 and 21 and at 180 min on day 20. For (A 2 ) g versus control, progesterone significantly increased every pregnancy day. For (NA 1 A 2 ) g versus (A 2 ) g , progesterone decreased at 120 and 180 min on day 19. For (NA 1 A 2 ) g versus NA, progesterone increased on days 20 and 21. We can conclude that A 2 can reverse the functional regression of the corpus luteum either systemically or, what is more surprising, when directly added to the coeliac ganglion, whose action on the ovary is exerted via superior ovarian nerve.
Steroids synthesized in the central nervous system are termed "neurosteroids". They are synthesized and metabolized in several brain areas. The objective of this work was to determine if 1 intracerebroventricular allopregnanolone injection in rats can interfere in luteal regression in a close relationship with modifications in LH, progesterone, and prolactin serum concentrations. Allopregnanolone was injected during proestrus morning and the animals were sacrificed on oestrous morning. Ovulation test and histological analysis were performed in the oestrus morning with light and electron microscopy. Serum prolactin, LH, and progesterone levels were measured by radioimmunoassay. The allopregnanolone injection significantly decreased luteinizing hormone serum level and the number of oocytes on oestrus. Progesterone and prolactin serum levels were increased after this injection. The inhibition of apoptotic figures due to allopregnanolone administration was detected in the already formed corpora lutea belonging to the previous ovary cycle and it was significantly lower than in vehicle group (control). When the GABA(A) antagonist (bicuculline) was administered alone or previously to allopregnanolone, no effect on the ovulation rate was observed. No changes in the apoptotic cell numbers were observed with respect to those of vehicle group. These results show that the effect of centrally injected allopreganolone over reproductive function could be due to a centrally originated LH mediated effect over ovarian function that affects luteal regression, through the inhibition of apoptosis and stimulation of progesterone and prolactin release.
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