| 1. |
- Jörgensen, Jörgen Ch, et al.
(författare)
-
The influence of neuropeptide Y and norepinephrine on ovulation in the rat ovary
- 1991
-
Ingår i: Peptides. - 1873-5169. ; 12:5, s. 975-982
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 2. |
- Liedberg, Fredrik, et al.
(författare)
-
Effects of vasoactive intestinal polypeptide (VIP) on the neuromuscular complex in the bovine ovarian follicle wall
- 1993
-
Ingår i: Journal of Autonomic Pharmacology. - : Wiley. - 0144-1795 .- 1365-2680. ; 13:3, s. 201-209
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 3. |
- Nilsson, Christer, et al.
(författare)
-
The neuropeptides vasoactive intestinal polypeptide, peptide histidine isoleucine and neuropeptide Y modulate [3H]noradrenaline release from sympathetic nerves in the choroid plexus
- 1990
-
Ingår i: European Journal of Pharmacology. - 1879-0712. ; 181:3, s. 247-252
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 4. |
- Schmidt, G, et al.
(författare)
-
Histaminergic effects on the isolated rat ovarian artery during the estrous cycle
- 1990
-
Ingår i: Biology of Reproduction. - 1529-7268. ; 42:5-6, s. 762-768
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
