Biomedical subjects

M Stjernquist

Publications and source records attributed to M Stjernquist.

41 records · Page 3Linked to original sources

PubMed1985

Cholinergic and adrenergic neural control of smooth muscle function in the non-pregnant rat uterine cervix.

The isolated circular smooth muscle of the uterine cervix from spayed rats was investigated in vitro. One group of animals was treated with oestrogen. Preparations from these rats showed no spontaneous contractile activity, but responded with contractions to electrical field stimulation. The contractions were blocked by approximately 85% with atropine, scopolamine and tetrodotoxin, but were unaffected by the adrenergic antagonists propranolol, phenoxybenzamine, and yohimbine. This neurogenic effect was potentiated by neostigmine. Noradrenaline inhibited the nerve-induced contractions and also lowered resting tension in a concentration-dependent way. The latter effect of noradrenaline was inhibited by propranolol. The indirect effects of noradrenaline on the electrically induced contractions were also inhibited by propranolol, but potentiated with phenoxybenzamine and, to a less extent, yohimbine. Nerve-induced relaxation was never observed. Acetylcholine contracted the smooth muscle by an effect that was counteracted by atropine. A second group of spayed rats was not given any steroid treatment. The cervix preparations from these animals showed spontaneous activity, which was uninfluenced by atropine, propranolol, phenoxybenzamine, yohimbine, and tetrodotoxin. Noradrenaline inhibited the spontaneous activity. This noradrenergic effect was counteracted by propranolol and potentiated by phenobenzamine. Acetylcholine increased the smooth-muscle tone by an atropine-sensitive action. The results suggest the presence of a cholinergic motor innervation on the non-pregnant rat uterine cervix. The cervix also receives an adrenergic innervation, which may act both post-junctionally (lowering resting tension and inhibiting spontaneous activity) and prejunctionally (modulating the cholinergic nerves) via beta-adrenergic as well as alpha-adrenergic receptors.

Adrenergic Fibers↗

PubMed1984

Vasoactive intestinal polypeptide (VIP) inhibits neurally evoked smooth muscle activity of rat uterine cervix in vitro.

VIP inhibits the spontaneous motor activity (including tone) in isolated preparations of uterine cervix from oophorectomized rats, but has no direct effect on preparations from estrogen-treated animals. Electrical field stimulation of nerves in the tissue evokes a contractile response that is inhibited by VIP in a concentration-dependent manner. The neuronal link probably involves a cholinergic mechanism, since the contraction is blocked by atropine. The results suggest the presence of VIP receptors both in cholinergic nerves and in smooth muscle cells of the rat uterine cervix.

Animals↗

PubMed1983

Neuropeptide Y in the female reproductive tract of the rat. Distribution of nerve fibres and motor effects.

Fluorescence immunocytochemistry revealed the presence of extensive systems of nerve fibres containing neuropeptide Y (NPY) in the rat's ovary, fallopian tube, uterine horns and cervix. The most prominent supply of NPY fibres was found in ther cervix, where they are associated with both vascular and non-vascular smooth musculature. Smooth muscle effect of NPY was studied in an in vitro model using circular cervix preparations from estrogen-treated sprayed rats. NPY onhibited in a dose-dependent way neurally evoked (tetrodotoxin-sensitive) contractions, but had no effect on resting tension. The nerve-induced contractions were blocked by atropine, the experiments thus suggest prejunctional actions of NPY in cholinergic nerves in the uterine cervix.

Animals↗

PubMed1983

Immunohistochemical localization of substance P, vasoactive intestinal polypeptide and gastrin-releasing peptide in vas deferens and seminal vesicle, and the effect of these and eight other neuropeptides on resting tension and neurally evoked contractile activity.

Immunohistochemical studies of the vas deferens and seminal vesicle of mouse, guinea-pig, and rabbit showed the presence of nerve fibres containing vasoactive intestinal polypeptide (VIP), substance P (SP), and gastrin-releasing peptide (GRP) supplying the smooth muscle layers as well as blood vessels. The nerve supply was better developed in the seminal vesicle than in the vas deferens. The motor activity of the vas deferens and seminal vesicle of the guinea-pig was studied in vitro. The vas deferens responded to transmural electrical stimulation with a twitch followed by a slow contraction. The twitch was blocked by guanethidine and tetrodotoxin, but not by atropine, propranolol, phenoxybenzamine, or fluphenazine. The slow contraction exhibited features of an alpha-receptor-mediated response. SP, physalaemin and eledoisin contracted the smooth muscle and also potentiated the twitch response to electrical nerve stimulation in a concentration-dependent manner. The SP blocking agent, (D-Pro2,D-Trp7,9)-SP, affected neither the resting tension nor the response to electrical stimulation. It is therefore suggested that the SP fibres act mainly prejunctionally. VIP, Leu-enkephalin, cholecystokinin octapeptide (CCK-8), angiotensin II, vasopressin, neurotensin, bombesin, and GRP had no effect on either the resting tension or the response to electrical nerve stimulation. The seminal vesicle responded to electrical stimulation with a contraction which was unimpaired by atropine, propranolol, phenoxybenzamine, and guanethidine, but abolished by tetrodotoxin. Hence, this contraction is mediated by a non-adrenergic, non-cholinergic neurotransmitter. Bombesin, GRP, SP, physalaemin and eledoisin contracted the smooth muscle and potentiated the response to electrical stimulation. VIP, Leu-enkephalin, CCK-8, angiotensin II, vasopressin, and neurotensin had no effect on the resting tension or on the response to transmural electrical stimulation. The SP antagonist abolished the contraction elicited by SP but did not influence the response to nerve stimulation. The results suggest that the SP and GRP nerves may have prejunctional and facilitating postjunctional effects in the seminal vesicle.

Animals↗

PubMed1981

Distribution and motor effect of VIP in female genital tract.

The distribution and concentration of vasoactive intestinal polypeptide (VIP) in different parts of the female genital organs from various species (cat, goat, pig, rabbit, rat, and guinea pig) were studied by means of immunohistochemistry and immunochemistry. In addition, the effect of VIP on the mechanical activity of uterine muscle was investigated in vitro. VIP immunoreactive nerve fibers innervating vessels and smooth muscle cells were fairly numerous in the genital organs of the cat and goat and less numerous in the pig, rabbit, rat, and guinea pig. In all species studied, VIP-containing nerves were most numerous in the cervix. The tissue concentration of VIP measured by immunochemistry was in agreement with the immunohistochemical findings. VIP inhibited the mechanical uterine activity in the cat, goat, pig, and rabbit, whereas only minimal effects were obtained in the rat and guinea pig. This difference between the species corresponded to the number of VIP-containing nerves in the uterine muscle. The data support the hypothesis that VIP may play a physiological role in the local nervous control of the uterine mechanical activity.

Animals↗