INHIBITORY EFFECT OF PROSTAGLANDIN F2α ON OXYTOCIN RELEASE AND ON MILK EJECTION IN LACTATING RATS

Prilusky, J.; Deis, R. P.

doi:10.1677/joe.0.0690395

Cited by 15 publications

(8 citation statements)

References 8 publications

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“…Prostagland Fi« (PGFj«) administered into the cerebroventricular system of the brain excites putative oxytocinergic cells in the paraventricular nucleus of the rat [1] coincident with increases in intramammary pressure. How ever, it has also been reported that milk ejection was sup pressed by intraperitoneal administration of PGF:« in lactating rats [15]. The study reported here does not help clar ify this particular issue, but we suggest that the great number of metabolic pathways of the arachidonate system may provide several mediators of OXY release, some excit atory and some inhibitory.…”

Section: Discussionmentioning

confidence: 52%

“…It has been recently re ported that OXY in the rat is released during stress portant interaction of OXY and prostaglandins in the uterus has led investigators to ask whether prostaglandins might not influence OXY release. The experimental evi dence favors the idea that prostaglandins stimulate OXY release [1,5,8], although evidence to the contrary has also been reported [15].We have demonstrated [12] that AVP, a closely related nonapeptide with two amino acid substitutions, is released after endotoxin administration and that the antipyretic and prostaglandin synthesis inhibiting drug, indomethacin, does not prevent this AVP release while ameliorating or preventing many other endotoxin-induced physiological changes.The aim of this study was to determine whether plasma OXY levels were affected by the stressors, endotoxin and hemorrhage, and whether indomethacin pretreatment would affect OXY release. …”

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confidence: 70%

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Indomethacin, an Antipyretic Drug, Prevents the Endotoxin-Induced and Potentiates the Hemorrhage-Induced Oxytocin Release into the Plasma of the Male Rat

Kasting¹

1986

Neuroendocrinology

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Oxytocin (OXY) is a nonapeptide of hypothalamic origin which has defined roles in the female reproductive functions of lactation and labor. However, OXY may have other physiological functions because of its presence in the male and its release in response to stress. Available evidence suggests prostaglandins may stimulate the release of OXY. These experiments sought to determine if the stressors, endotoxin and hemorrhage, would release OXY in the chronically catheterized, freely behaving male rat and what effect the antipyretic and prostaglandin synthesis inhibiting drug, indomethacin, would have on these responses. Endotoxin caused a marked release of OXY from mean baseline levels of 5 pg/ml to mean peak levels of 168 pg/ml. Indomethacin greatly attenuated this increase. In contrast, OXY release in response to hemorrhage of either 22 or 44%of the blood volume of the rat was enhanced by indomethacin. Indomethacin increased the hemorrhage-induced OXY levels about 2-fold over a 2-hour posthemorrhage period. Indomethacin alone had no effect on OXY levels. These data verify that stress is a potent stimulus for OXY release and strengthen the hypothesis that prostaglandins mediate OXY release. The paradoxical effects of indomethacin on OXY release suggest that the prostaglandins may have different effects on OXY release depending upon the evoking stimulus.

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Section: Discussionmentioning

confidence: 52%

mentioning

confidence: 70%

Indomethacin, an Antipyretic Drug, Prevents the Endotoxin-Induced and Potentiates the Hemorrhage-Induced Oxytocin Release into the Plasma of the Male Rat

Kasting¹

1986

Neuroendocrinology

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“…PGE 2 has hyperthermic (7), sedative (8), anticonvulsive (9,10), and antidiuretic effects (11) and induces wakefulness (12,13), stimulates luteinizing hormone-releasing hormone release (14), modifies pain (5,9), and regulates food intake (11). Also, PGF 2␣ has an antidiuretic effect (15) and an inhibitory effect on oxytocin release (16). These three PGs are reported to be involved in the modulation of neurotransmitter release as well (17).…”

mentioning

confidence: 99%

A Novel Subtype of the Prostacyclin Receptor Expressed in the Central Nervous System

Takechi¹,

Matsumura²,

Watanabe³

et al. 1996

Journal of Biological Chemistry

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By use of several prostacyclin analogs and an in vitro autoradiographic technique, we have found a novel subtype of the prostacyclin receptor, one having different binding properties compared with those of the known prostacyclin receptor in the rat brain. Isocarbacyclin, which is a potent agonist for the known prostacyclin receptor, had high affinity for the novel subtype (dissociation constant (K d ) of 7.8 nM). However, iloprost, which is usually used as a stable prostacyclin analog, showed low affinity binding ( 3 H]iloprost also had high affinity in these regions, and the binding specificity was similar to that for the known prostacyclin receptor. Hemilesion studies of striatal neurons lesioned by kainate or of dopaminergic afferents lesioned by 6-hydroxydopamine revealed that the binding sites of the novel subtype exist on neuronal cells in the striatum, but not on the presynaptic terminal of afferents or on glial cells. Electrophysiological studies carried out in the CA1 region of the hippocampus revealed that prostacyclin analogs have a facilitatory effect on the excitatory transmission through the novel prostacyclin receptor. The widespread expression of the prostacyclin receptor in the central nervous system suggests that prostacyclin has important roles in neuronal activity. Prostaglandins (PGs)1 and thromboxane are formed from arachidonic acid by cyclooxygenase and the respective synthase for each PG, such as PGD synthase and PGI 2 synthase. These prostanoids exert a variety of functions through their specific membrane receptors coupled to G proteins not only in the peripheral organs, but also in the central nervous system. For example, PGD 2 acts as a sleep inducer (1, 2), produces hypothermia (3), inhibits luteinizing hormone-releasing hormone release (4), and is involved in biphasic modulation of pain sensation (5) and modification of olfaction (6). PGE 2 has hyperthermic (7), sedative (8), anticonvulsive (9, 10), and antidiuretic effects (11) and induces wakefulness (12, 13), stimulates luteinizing hormone-releasing hormone release (14), modifies pain (5, 9), and regulates food intake (11). Also, PGF 2␣ has an antidiuretic effect (15) and an inhibitory effect on oxytocin release (16). These three PGs are reported to be involved in the modulation of neurotransmitter release as well (17). Prostacyclin, discovered in 1976, is known to be a potent vasodilator and also to have an inhibitory effect on platelet aggregation (18). In the brain, however, it is not clear whether prostacyclin has specific functions or not. It seems that the chemical instability of prostacyclin and lack of knowledge about the prostacyclin receptor in the brain have hampered the investigation.Recently, we reported the presence and distribution of the prostacyclin receptor in the central nervous system by use of [ 3 H]iloprost, a stable prostacyclin analog, and an in vitro autoradiographic technique (19). High density binding was observed in the nucleus of the solitary tract (NTS) and in the spinal trigeminal nucleus in the lowe...

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“…but Prilusky & Deis (1976) could find no such response in anaesthetized rats. In the present study the effect of an intramuscular injection of PGF2a was studied in four Landrace pigs (weighing 106-108 kg) during dioestrus and four miniature pigs (weighing 45-50 kg) six days post partum.…”

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confidence: 80%

PROCEEDINGS OF THE British Pharmacological Society

1978

British J Pharmacology

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INHIBITORY EFFECT OF PROSTAGLANDIN F2α ON OXYTOCIN RELEASE AND ON MILK EJECTION IN LACTATING RATS

Cited by 15 publications

References 8 publications

Indomethacin, an Antipyretic Drug, Prevents the Endotoxin-Induced and Potentiates the Hemorrhage-Induced Oxytocin Release into the Plasma of the Male Rat

Indomethacin, an Antipyretic Drug, Prevents the Endotoxin-Induced and Potentiates the Hemorrhage-Induced Oxytocin Release into the Plasma of the Male Rat

A Novel Subtype of the Prostacyclin Receptor Expressed in the Central Nervous System

PROCEEDINGS OF THE British Pharmacological Society

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