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R G Dyer

Publications and source records attributed to R G Dyer.

84 records · Page 5Linked to original sources
PubMed1971

Unit activity in rat diencephalic islands--the effect of anaesthetics.

1. Unit activity was recorded with steel micro-electrodes from 486 hypothalamic neurones in rat diencephalic island preparations.2. The histograms of firing frequencies for populations of hypothalamic units from unanaesthetized preparations and from those under urethane anaesthesia were not significantly different. The firing rates of both were significantly faster than those observed in intact brains under urethane.3. The mean distance between stable units in unanaesthetized island preparations did not differ significantly from that in preparations anaesthetized with urethane.4. The response of individual neurones to intravenous injections of urethane was variable, and apparently not associated with the onset or maintenance of anaesthesia. Some showed transient acceleration, some deceleration and some no change in rate or pattern of discharge.5. All neurones tested were slowed or stopped by intravenous injections of subanaesthetic doses of sodium methohexitone (Brietal). The responses were highly reproducible and dose-dependent.6. Brietal also produced a fall in arterial pressure and depressed respiration. Inhalation of amyl nitrite evoked larger hypotensive responses but did not affect unit activity; nor did inhalation of CO(2) (hypercapnia) or N(2)O (hypoxia).7. It is concluded that urethane anaesthesia is not associated with any direct action on hypothalamic neurones. The depression of firing rate in hypothalamic neurones induced by Brietal may represent an important forebrain mechanism in anaesthesia by this agent.

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PubMed1971

Plasma oxytocin concentration and paraventricular neurone activity in rats with diencephalic islands and intact brains.

1. Plasma oxytocin concentrations and the discharge rates of identified paraventricular neurones were compared in intact animals and diencephalic island preparations.2. Substantial amounts of oxytocin (88-322 muu./ml.) were found in the plasma of intact rats but in no case was it detected in the plasma of island preparations. The discharge rate of paraventricular units was also significantly reduced in these preparations.3. The results are consistent with the hypothesis that an increase in the discharge rate of paraventricular neurones is associated with oxytocin release from the neurohypophysis.4. The discharge rates of identified paraventricular units were not affected by intravenous injections of oxytocin either in intact animals or island preparations.

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