Localization of neurophysin-II in the hypothalamo-neurohypophysical system of the pig by immunofluorescence histochemistry

Livett, Bruce G.; Uttenthal, L. O.; Hope, D. B.

doi:10.1098/rstb.1971.0067

Cited by 57 publications

(5 citation statements)

References 21 publications

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“…We may also conclude that the responsive neurones represent 'oxytocinergic neurones' for current evidence suggests that vasopressin is not released in detectable amounts during suckling in the rat (Wakerley, Dyball & Lincoln, 1973). This is entirely consistent with the overwhelming evidence that the hypothalamo-neurohypophysial system is organized on a Cone cell to one hormone' principle (Sokol & Valtin, 1967;Livett, Uttenthal & Hope, 1971;Hayward & Jennings, 1973).…”

Section: Relationship Of Neurosecretory Activation To Oxytocin Releasesupporting

confidence: 71%

Factors governing the periodic activation of supraoptic and paraventricular neurosecretory cells during suckling in the rat.

Lincoln¹,

Wakerley²

1975

The Journal of Physiology

147

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SUMMARY1. One hundred and thirty-two antidromically identified paraventricular (PV) and supraoptic (SO) neurones were studied during milk ejection evoked by the suckling of the young, in thirty-four lactating rats anaesthetized with urethane (1.1 g/kg i.P.). The spike activity of these neurones was analysed to determine some of the factors governing their orthodromic activation. Changes in spike activity were compared with the amount of oxytocin released from the neurohypophysis, as measured by the rise in intramammary pressure at milk ejection.2. Sixty-five units, from both the PV and SO nuclei, displayed a characteristic burst of accelerated activity 12-18 sec before milk ejection. With a suckling stimulus of nine or ten pups, these neurosecretory responses were both regular in their occurrence (recurring every 4-8 min) and uniform in character, i.e. all responsive cells accelerated to 30-80 spikes/sec for 1-4 sec. Two units deviated from this pattern and both were recorded in animals which failed to display a detectable milk ejection. Both cells displayed diminutive responses (10-20 spikes/sec, for 0 5 sec) at regular intervals.3. The number of suckling pups was the most important factor controlling both the occurrence and expression of the neurosecretory response. When successive pups were removed from the nipples there was a progressive and linearly related fall in the magnitude of the unit responses, i.e. the peak firing rate and the number of spikes in each response declined. Neurosecretory activation was normally not observed in anaesthetized and stereotaxically restrained animals when six pups or less were placed to suckle. D. W. LINCOLN AND J. B. WAKERLEY neurosecretory activation had an important influence on the expression of the unit response. On a population basis and ignoring variations created by differences in the number of suckling young, units with background firing rates of > 1*0 spikes/sec displayed responses that were significantly (P < 0.05) greater (peak rate x number of spikes) than those units firing at < 1-0 spikes/sec. This correlation was also observed with single units, particularly where large fluctuations in background firing rate were encountered.5. When five to seven pups were placed to suckle -a threshold number, two factors were observed to occasionally trigger a neurosecretory response. These were the injection of 0 05 ml. saline into one of the cannulated mammary glands, and the addition or removal of a pup. In either case the response was immediate and occurred with both ipsilateral and contralateral stimulation.6. The amount of oxytocin released in response to each period of neurosecretory activation was always proportional to the magnitude of the response displayed by the individual unit, thus a larger pulse of oxytocin was released in response to the suckling of nine pups than seven pups. All suckling-induced milk ejections were the result of oxytocin being released in pulses of 0-2-1'5 m-u.7. We found no conclusive evidence to suggest that the number of pups or the suck...

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Section: Relationship Of Neurosecretory Activation To Oxytocin Releasesupporting

confidence: 71%

Factors governing the periodic activation of supraoptic and paraventricular neurosecretory cells during suckling in the rat.

Lincoln¹,

Wakerley²

1975

The Journal of Physiology

147

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“…These facts are best explained by the existence within the hypothalamo-neurohypophysial system of two populations of neurosecretory cells: one 'oxytocinergic' and the other 'vasopressinergic'. This view is supported by recent studies using immunohistochemical techniques in which it has been possible to visualize individual neurosecretory cells containing neurophysin I (Zimmerman, Hsu, Robinson, Carmel, Frantz & Tannenbaum, 1973) and neurophysin II (Livett, Uttenthal & Hope, 1971;Watkins & Evans, 1972): these would correspond to oxytocinergic and vasopressinergic cells, respectively. We conclude, therefore, that vasopressin is not released in any substantial amount during suckling (a few microunits might be released) and consider that the responsive SO units that we have observed confirm the presence of oxytocinergic cells within the SO nuclei.…”

Section: Background Activity Of So Units During Sucklingsupporting

confidence: 58%

Electrophysiological evidence for the activation of supraoptic neurones during the release of oxytocin

Lincoln¹,

Wakerley²

1974

The Journal of Physiology

258

124

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SUMMARY1. Antidromically identified supraoptic (SO) units were recorded in lactating rats anaesthetized with urethane (1.1 g/kg), and their activity was studied during milk ejection evoked by the suckling of the young. Fifty-eight SO units were recorded through 174 milk ejections. Each milk ejection was the result of a neurohypophysial release of an oxytocin pulse of 0.5-1-5 m-u.2. Fifty-five of the SO units displayed background activity and three were silent. The firing rates ranged from 0 to 15-4 spikes/sec, the distribution was exponential with 26 % of the units firing at < 1 spike/sec. Sixteen (28 %) of the SO units displayed a phasic pattern of activity characterized by periods of activity (6-132 sec) and silence (4-71 sec).3. Twenty-five of the non-phasic units displayed a large and stereotyped acceleration in spike activity some 10-5-17-4 see before the rise in intramammary pressure at milk ejection. Units accelerated to rates between 9-66 spikes/sec, an increase of about thirtyfold (median) on background activity. The response was brief (0.9-4.7 see) and was followed by a period of after-inhibition.4. It was concluded from studies of double recordings and observations of multi-unit activity that all the responsive units were synchronously activated. The mean latency of 13-3 sec between the onset of the neurosecretory response and milk ejection was similar to that observed following the experimental release of endogenous oxytocin by electrical stimulation of the neurohypophysis (50 pulses/sec for 2-4 sec).5. Four of the phasically active units were correlated with the oxytocin release for milk ejection. Three of these units displayed a burst of activity superimposed on the terminal portion ofan active phase, some 10 2-14*7 see

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“…Studies of the localization of porcine NP-I1 within the pig hypothalamus using fluorescent antibodies specific for porcine NP-I1 demonstrated that it was located in the supraoptic nucleus (70). Because vasopressin originally appeared to be synthesized predominantly in the supraoptic nucleus and oxytocin in the paraventricular nucleus, these results were originally interpreted as indicating the in vivo association of porcine NP-I1 with lysine vasopressin.…”

Section: B Association Of Neurophysin With the Hormones In Neurosecrmentioning

confidence: 98%

“…Because vasopressin originally appeared to be synthesized predominantly in the supraoptic nucleus and oxytocin in the paraventricular nucleus, these results were originally interpreted as indicating the in vivo association of porcine NP-I1 with lysine vasopressin. This was a particularly attractive hypothesis since porcine NP-I1 may differ from most other neurophysins in its monomeric molecular weight (see Table I) and the pig differs from most other mammals in that it has lysine, rather than arginine, vasopressin; thus an unusual vasopressin appeared to be associated in evolution with an unusual neurophysin (70). More recently, however, neurosecretory granules from porcine posterior pituitary have been partially fractionated by centrifugation in a sucrose-density gradient (73).…”

Section: B Association Of Neurophysin With the Hormones In Neurosecrmentioning

confidence: 99%

The Neurophysins

Breslow¹

1974

Advances in Enzymology - And Related Areas of Molecular Biology

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Localization of neurophysin-II in the hypothalamo-neurohypophysical system of the pig by immunofluorescence histochemistry

Cited by 57 publications

References 21 publications

Factors governing the periodic activation of supraoptic and paraventricular neurosecretory cells during suckling in the rat.

Factors governing the periodic activation of supraoptic and paraventricular neurosecretory cells during suckling in the rat.

Electrophysiological evidence for the activation of supraoptic neurones during the release of oxytocin

The Neurophysins

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