Observations on the loss of catecholamine fluorescence from intrauterine adrenergic nerves during pregnancy in the guinea-pig

Bell, Christopher J.; Malcolm, S. J.

doi:10.1530/jrf.0.0530051

Cited by 64 publications

(38 citation statements)

References 10 publications

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“…Changes in perivascular innervation in pregnancy have been described in the uterine artery of the guinea-pig, involving a decrease in NA-, and an increase in CGRP-, substance P-, vasoactive intestinal peptide-and neuropeptide Y-containing nerves (Bell & Malcolm, 1978;Tare et al, 1988;Mione et al, 1993). A decrease in sympathetic responses to EFS and in endogenous NA levels, and an increase in neuronally-mediated dilatation (mediated in part by NO) has been reported in pregnant human uterine arteries (Nelson et al, 1995).…”

Section: Discussionmentioning

confidence: 99%

Mesenteric arterial function in the rat in pregnancy: role of sympathetic and sensory‐motor perivascular nerves, endothelium, smooth muscle, nitric oxide and prostaglandins

Ralevic

Burnstock

1996

British J Pharmacology

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1 The effects of pregnancy on mesenteric arterial function were examined in constantly perfused (5mlmin-1) mesenteric arterial beds isolated from 21-day pregnant rats. The function of sympathetic and sensory-motor perivascular nerves, endothelium and smooth muscle was examined. The role of nitric oxide and prostaglandins in vasoconstrictor function was tested by use of NG-nitro-L-arginine methyl ester (L-NAME; 100 uM) and indomethacin (10 iM), respectively.2 Electrical field stimulation (EFS; 4-32 Hz, 1 ms, 90 V, 30 s) at basal tone elicited frequency-dependent vasoconstriction which was markedly reduced in preparations from pregnant rats at all frequencies. Vasoconstrictor responses to vasopressin and endothelin were also reduced in pregnancy and there was a trend towards a reduction in maximal responses to noradrenaline (NA). In contrast, there was no difference in vasoconstrictor responses to ATP, 5-hydroxytryptamine (5-HT) or angiotensin II. 3 L-NAME (100 gM) augmented responses to EFS, NA, ATP and vasopressin in control mesenteric arterial preparations. In contrast, L-NAME augmented responses only to EFS in pregnancy, having no significant effect on responses to NA, ATP and vasopressin.4 Indomethacin (10 gM) attenuated responses to NA and vasopressin, but not to EFS, in controls and in pregnancy. Responses to ATP were attenuated by indomethacin in controls but not in pregnancy. 5 Mesenteric preparations from pregnant rats were resistant to having tone raised by continuous perfusion with methoxamine. Despite an approximately 10 fold greater concentration of methoxamine, there was a significantly smaller increase in tone in preparations from pregnant, 34.27+4.8mmHg(n= 11) compared to control, 65.92+5.4mmHg (n= 11), rats. EFS (4-12Hz, 60V, 0.1Ims, 30s) in the presence of guanethidine (5 gM) to block sympathetic neurotransmission elicited frequency-dependent vasodilatation due to activation of sensory-motor nerves. Percentage relaxations were similar in preparations from pregnant and non-pregnant rats. 6 Dose-dependent endothelium-dependent vasodilatations to acetylcholine and ATP were similar in preparations from pregnant and non-pregnant rats. Endothelium-independent vasodilatation to sodium nitroprusside and to calcitonin gene-related peptide were also similar between the two groups. 7 There was no significant difference in the basal perfusion pressure of mesenteric arterial beds from control (21.3 + 1.0 mmHg, n = 24) and pregnant (20.2 + 1.2 mmHg, n = 23) rats. However, a step-wise increase in perfusate flow from 5 to 10, 15, 20 and 24 ml min-' produced smaller increases in perfusion pressure in pregnancy compared to the controls. L-NAME (100,tM) or indomethacin (10jiM) had no significant effect on the relationship between flow and perfusion pressure. 8 The present results show that prejunctional changes are involved in blunted sympathetic vasoconstriction of rat mesenteric arteries in pregnancy. Non-specific postjunctional changes are implicated in the reduced constrictor responses to applied methoxamine, ...

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Section: Discussionmentioning

confidence: 99%

Mesenteric arterial function in the rat in pregnancy: role of sympathetic and sensory‐motor perivascular nerves, endothelium, smooth muscle, nitric oxide and prostaglandins

Ralevic

Burnstock

1996

British J Pharmacology

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“…The adrenergic innervation of the uterus is known to be under special hormonal influence and undergoes structural and functional changes during pregnancy [9][10][11], The changes in hormonal concentrations during the human menstrual cycle may also have an influence on this innervation, since the effect of p-adrenergic stimula tion, at least on the myometrial activity, varies accord ingly [12], Studies of the human uterine artery innerva tion under different hormonal conditions are therefore indicated.…”

Section: Discussionmentioning

confidence: 99%

Innervation of the Human Uterine Artery and Contractile Responses to Neuropeptides

Ekesbo¹,

Alm

Ekström³

et al. 1991

Gynecol Obstet Invest

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The intrinsic innervation of the human uterine artery was investigated histochemically, and the motor responses to some of the demonstrated peptides and other humoral factors were studied on isolated vascular preparations. There were nerves with specific immunoreactivities for tyrosine hydroxylase, dopamine Β-hydroxylase, neuropeptide-Y (NPY), vasoactive intestinal peptide (VIP) and peptide histidine methionine, and enzymatic reactivity for acetylcholine esterase. The most effective stimulator of smooth muscle contractility was arginine vasopressin followed in order by oxytocin, noradrenaline together with NPY, noradrenaline alone and dopamine. No effect was seen with acetylcholine and tyrosine, and VIP caused inconsistent relaxation of contractile activity induced by PGF_2Α. These results suggest that the uterine blood flow is regulated by complex interactions of factors, some occurring in nerve terminals and some being circulating humoral factors.

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“…In the guinea-pig, pregnancy induces degeneration of uterine short adrenergic neurones (GArdmark, Owman & Sj6berg, 1971;Owman & Sj6berg, 1973;Bell & Malcolm, 1978;Thorbert, Alm, Owman, Sjcberg & Sporrong, 1978;Owman, 1981). This effect, together with an effect of high circulating levels of oestrogen and progesterone causing a functional loss of a-adrenoceptors, such as that reported here, would protect the longitudinal myometrium from excitation arising from sympathetic activation during pregnancy.…”

Section: Discussionmentioning

confidence: 64%

Effects of ovarian steroids upon responses mediated by adrenoceptors in separated layers of the myometrium and in the costo‐uterine muscle of the guinea‐pig

Hartley

Pennefather

Story

1983

British J Pharmacology

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1This study describes the effects of ovarian steroid hormones upon the responses to adrenoceptor agonists of isolated myometrium, separated into its longitudinal and circular layers, and of costo-uterine muscle from guinea-pigs. The preparations were field-stimulated at 100s intervals, and the adrenoceptor agonists phenylephrine and isoprenaline produced enhancement or inhibition of the evoked contractions. 2 Isoprenaline produced propranolol-sensitive inhibitory effects in longitudinal and circular myometrium and costo-uterine muscle preparations from animals from all experimental groups: i.e. from nonsteroid-treated animals (ovariectomized and intact); intact animals treated with either oestrogen or progesterone alone; ovariectomized animals treated with oestrogen; ovariectomized and intact animals treated with progesterone following oestrogen priming; and from animals 1-4 days post-partum. Longitudinal myometrial preparations from progesterone-treated oestrogenprimed and from post-partum animals were most sensitive to this agonist. 3 Phenylephrine produced phentolamine-sensitive excitatory effects in circular myometrial and costo-uterine muscle preparations from animals from all the experimental groups. In contrast, propranolol-sensitive inhibitory responses to phenylephrine occurred in longitudinal myometrial preparations taken from animals treated with progesterone following oestrogen priming, and from post-partum animals. Longitudinal myometrium from animals from the remaining experimental groups exhibited phentolamine-sensitive excitatory responses to phenylephrine. 4 The basis for the selective effect upon the longitudinal myometrium of exposure to progesterone following a period of oestrogen priming, is discussed. The results described are consistent with the possibility that in the longitudinal layer of guinea-pig uterus exposed to progesterone following oestrogen priming there is an increase in the proportion of P-adrenoceptors in this layer. This increase may reduce the likelihood of contractions arising via direct stimulation of oa-adrenoceptors in this layer in response to sympathetic activation during pregnancy.

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Observations on the loss of catecholamine fluorescence from intrauterine adrenergic nerves during pregnancy in the guinea-pig

Cited by 64 publications

References 10 publications

Mesenteric arterial function in the rat in pregnancy: role of sympathetic and sensory‐motor perivascular nerves, endothelium, smooth muscle, nitric oxide and prostaglandins

Mesenteric arterial function in the rat in pregnancy: role of sympathetic and sensory‐motor perivascular nerves, endothelium, smooth muscle, nitric oxide and prostaglandins

Innervation of the Human Uterine Artery and Contractile Responses to Neuropeptides

Effects of ovarian steroids upon responses mediated by adrenoceptors in separated layers of the myometrium and in the costo‐uterine muscle of the guinea‐pig

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