Stimuli for the Release of Neurohypophysial Hormones

Dyball, R. E. J.

doi:10.1111/j.1476-5381.1968.tb00993.x

Cited by 21 publications

(25 citation statements)

References 26 publications

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“…Many neural and chemical stimuli have been shown to evoke changes m rate of neurone discharges in the SON and PVN (Suda et al 1963;Koizumi et al 1964;Ishikawa, Koizumi & Brooks, 1966;Brooks et al 1966;Dyball & Koizumi, 1969) as well as in ADH and oxytocin release (Dyball, 1968(Dyball, , 1971. Originally, cells were considered to be neurosecretory cells when they were anatomically located in the PVN and SON and were osmosensitive (Koizumi et al 1964;Brooks et al 1966;Ishikawa et al 1966 (Harris, 1955).…”

Section: Control Of Neurosecretory Cellsmentioning

confidence: 99%

Studies of antidromically identified neurosecretory cells of the hypothalamus by intracellular and extracellular recordings

Koizumi¹,

Yamashita²

1972

The Journal of Physiology

154

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SUMMARY1. Neurosecretory neurones in supraoptic (SON) and paraventricular (PVN) nuclei of the hypothalamus of cats, anaesthetized with chloralose, and dogs, anaesthetized with Nembutal, were studied. These neurosecretory neurones were identified by action potentials evoked antidromically following stimulation of the posterior lobe of the pituitary gland. Reactions of 158 such neurones in cats and 228 in dogs were analysed.2. The latencies of antidromic potentials evoked in neurosecretory neurones by posterior lobe stimulation were between 10 and 22 msec for SON and between 14 and 28 msec for PVN cells. Approximate speed of conduction in the axons was 0 4-0 9 m/sec. The absolute refractory period for the soma-dendritic (SD) spike was 5-10 msec. These cells followed repetitive stimulation up to a rate of 100/sec.A notch was generally present on the rising phase of antidromic potentials and when the antidromically conducted signal fell in the relative refractory period of the preceding response, a complete separation between this first small A-spike and later large B-spikes, probably soma-dendritic spike, frequently occurred. Thus, two responses, a small and a large, sometimes appeared with more than 10 msec intervening. When the second antidromic response fell in the absolute refractory period of the first, the B-spike was blocked and only the A-spike appeared.3. Intracellular recordings from neurosecretory cells, mainly from SON in the dog, showed that these neurones possess resting membrane potentials of 50-80 mV, and action potentials of the same magnitude.In spontaneously firing neurosecretory cells separate A-and B-spikes also occurred and could be recorded intracellularly. three spikes with latencies of 10-30 msec. Excitation was followed by an inhibition, of 'spontaneous' discharges as well as of subsequent antidromic excitation, lasting 100-500 msec. Intracellular recordings from neurosecretory cells showed that stimulations of the septal area and RF produced action potentials or EPSPs of short duration followed by long lasting IPSPs. Hyperpolarization was always longer than the preceding EPSP, and its duration was generally 80 msec. Large IPSPs of 20 mV could be recorded occasionally.7. Antidromic excitation of neurosecretory cells by stimulation of the posterior pituitary was followed by the inhibition of 'spontaneous' discharges of the cells. This inhibition usually lasted for 100 msec. A corresponding IPSP was recorded during this inhibitory phase. These findings indicate the existence of recurrent collaterals in neurosecretory cells.8. This conclusion that recurrent collaterals exist was also supported by other evidence, namely, that certain neurones were found in the SON and PVN which responded to a single pulse antidromic stimulation of the posterior pituitary with five to seven discharges at a rate of between 500 and 800/sec. Weaker stimuli produced fewer spikes. Such cells resembled in their behaviour 'Renshaw cells' of the spinal cord. RF stimulation had an inhibitory effect on some of these neur...

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Section: Control Of Neurosecretory Cellsmentioning

confidence: 99%

Studies of antidromically identified neurosecretory cells of the hypothalamus by intracellular and extracellular recordings

Koizumi¹,

Yamashita²

1972

The Journal of Physiology

154

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“…If the oxygen atom which links the carbamate and choline groups in the carbachol molecule is considered to be comparable with the nitrogen atom in the phenothiazine ring of promethazine, a structural similarity between promethazine and carbachol can be seen. This provides a possible chemical basis for the proposed cholinomimetic action of promethazine because carbachol is structurally very closely related to acetylcholine and if injected into the common carotid artery can itself cause some release of vasopressin (Dyball, 1968). 2.…”

Section: Resultsmentioning

confidence: 99%

“…The other compounds have similar pharmacological properties (Pratesi, 1964(Pratesi, , 1965. Table 1, which summarizes some results-reported in a previous paper (Dyball, 1968), shows that the atropine sulphate used for -premedication of the. experimental animals before the induction of the ether anaesthesia did not affect the release of vasopressin by the three stimuli chosen.…”

Section: Methodsmentioning

confidence: 99%

“…Three stimuli which had been found to be consistently effective in releasing vasopressin in the experimental conditions used (Dyball, 1966(Dyball, , 1968 were employed. (1) Electrical stimulation of the central end of the severed right vagus nerve (stimulation for 30 sec with a break of 2 sec between the fifteenth and seventeenth sec at 15 V with square waves of 2 msec duration and 100 c/s); (2) injection of 0.1 M calcium chloride solution to 6.3 ml./kg (at a rate of 0.6 ml./min) into the right common carotid artery (=approximately 25 mg Ca++/kg); (3) haemorrhage.…”

Section: Methodsmentioning

confidence: 99%

“…The purpose of the experiments described here was to investigate the effects of a number of drugs on the release of vasopressin by the three stimuli found most effective in a previous investigation (Dyball, 1966(Dyball, , 1968. Drugs were chosen which antagonize the action of acetylcholine, adrenaline and noradrenaline, 5-hydroxytryptamine and histamine because there is good circumstantial evidence that these substances may be chemical transmitters in the central nervous system (Crossland, 1960).…”

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The Effects of Drugs on the Release of Vasopressin

Dyball

1968

British Journal of Pharmacology and Chemotherapy

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Effects of hormone-releasing stimuli on the area of the perivascular space in the neural lobe of the rat

Livingston

1978

Cell Tissue Res.

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Neural lobes from rats subjected to neurohypophysial hormone-releasing stimuli were examined electron microscopically following fixation in 4% tannic acid in 2.5% glutaraldehyde. This fixation allowed the delineation of the perivascular space in the neural lobe tissue. Measurement of the area of the perivascular space showed that it was significantly increased in the rats subjected to vagal stimulation and intraarterial calcium ions compared to the control rats. The rats which had been subjected to haemorrhage as a hormone-releasing stimulus did not show any significant change in the area of the perivascular space. The significance of these findings in relation to hormone release is discussed.

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Stimuli for the Release of Neurohypophysial Hormones

Cited by 21 publications

References 26 publications

Studies of antidromically identified neurosecretory cells of the hypothalamus by intracellular and extracellular recordings

Studies of antidromically identified neurosecretory cells of the hypothalamus by intracellular and extracellular recordings

The Effects of Drugs on the Release of Vasopressin

Effects of hormone-releasing stimuli on the area of the perivascular space in the neural lobe of the rat

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