Alastair J S Summerlee

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1. Extracellular electrical recordings were taken from nine antidromically identified paraventricular units in unanaesthetized, unrestrained rats. Neuronal activity was correlated with the observed events of parturition, i.e. abdominal contractions and delivery of young or placentae. 2. The level of spontaneous activity (0.15--3.2 spikes s-1) of all nine(More)
Electroencephalographic activity (EEG) was recorded from the frontal cortex of unanaesthetized and urethane-anaesthetized lactating rats and analysed in relation to the pattern of milk ejection evoked by the nursing pups. The EEG of the anaesthetized rat fluctuated without experimental intervention between three distinctive patterns defined as synchronized,(More)
A method is described for making extracellular recordings of the spontaneous activity of single hypothalamic neurones in unanaesthetized, freely moving, lactating rats using chronically implanted micro-wire electrodes. Extracellular recordings taken from individual neurones were maintained for periods of between 1 and 12 days. These records were not(More)
The novel finding that relaxin has an action on the brain was first published in 1984. Since then, it has been shown that exogenous relaxin affects the release of a number of hypothalamo-pituitary hormones and has a robust pressor action. In this paper, we review the accumulating evidence that relaxin affects the release of oxytocin and vasopressin by an(More)
The extracellular electrical activity of magnocellular neurones was recorded from unanaesthetized, unrestrained rabbits in birth and the post partum suckling period. The activity of oxytocin neurones was differentiated from that of vasopressin cells on the basis of their stereotyped activity in suckling. Oxytocin neurones showed five to fourteen discrete(More)
Experiments were done to examine whether rat relaxin is dipsogenic and whether such dipsogenic effects of rat relaxin are related to time of injection during the light-dark cycle. Female rats were fitted with a chronic intra-cerebro-ventricular (i.c.v.) cannula. Rat relaxin (2.5, 5, 10, 25, 50, or 100 ng/2 microl in 0.9% saline) was injected into the right(More)
Abstract Experiments were done to examine the pressor effect of iv porcine relaxin in anaesthetized rats. Acute injections of relaxin caused consistent and sustained rises in systemic blood pressure that were dose-dependent within the physiological range. Pretreatment of rats with a specific vasopressin (V1) receptor antagonist, but not an(More)
In several species the myometrium is quiescent shortly before parturition. At this time high titres of relaxin are present in the plasma and there is evidence that the hormone has a direct inhibitory action on the uterine muscle. Relaxin could also contribute to uterine quiescence by inhibiting oxytocin release. To determine whether relaxin has a central(More)
Abstract The effects of intravenous injection of porcine relaxin on the pulsatile secretion of luteinizing hormone (LH) were investigated in conscious rats. In untreated, ovariectomized animals, relaxin at doses 2.5 to 10/mug/rat caused a dose-dependent suppression of pulsatile release of LH. At 5mug relaxin, pulses were suppressed for approximately 60 min(More)
Work reported in this chapter describes the potential role of relaxin in resetting cardiovascular thresholds in pregnant rats. Relaxin, a polypeptide produced primarily by the ovary in pregnant animals in many species, is also produced in the brain. Exogenous administration of relaxin into the brain causes a profound drinking response which is negated by(More)