Studies of the Antidiuretic Activity of Blood and Hypothalamus of Hypophysectomized Rats

Lloyd, Charles W.; Pierog, Sophie

doi:10.1210/endo-56-6-718

Cited by 23 publications

(7 citation statements)

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“…Whether or not the restoration of the reflex is dependent on the hypertrophy of the stalk is undecided and further experiments are being planned to investigate this. It is clear that the above findings are in full accord with the view that the hormone(s) of the posterior pituitary are formed in the supraoptic and paraventricular nuclei of the hypothalamus and are carried down the axones of the hypothalamo-hypophysial tract into the neural lobe and that if the neural lobe be removed the reorganized end of the stalk can assume some of the functions of the neural lobe [Lloyd & Pierog, 1955]. Posterior lobectomy in the rat reduces the number of cells in the supraoptic and paraventricular nuclei to 34 and 37 % of normal, respectively [Bodian & Maren, 1951], but those remaining appear to be able to produce adequate oxytocin for normal milk ejection.…”

Section: Discussionsupporting

confidence: 65%

“…This is in agreement with results of assays of the amount of antidiuretic hormone in the blood and hypothalamus of the rat following hypophysectomy. It has been demonstrated that while antidiuretic hormone activity disappears from the blood immediately after hypophysectomy, it reappears in the blood within a month [Lloyd, Loewy, Pierog, Bradwick & Sostheim, 1954;Lloyd & Pierog, 1955]. In addition, Lloyd and Pierog found that whereas the hypothalamus of recently hypo¬ physectomized animals contained little antidiuretic hormone, 30 days after hypo¬ physectomy the hypothalamus contained quantities of antidiuretic hormone similar to those found in the hypothalamus of intact animals.…”

Section: Discussionmentioning

confidence: 99%

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Lactation in the Rat After Hypophysial Posterior Lobectomy

Benson¹,

Cowie²

1956

Journal of Endocrinology

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Ablation of the posterior lobe of the pituitary in the lactating rat abolished the milk-ejection reflex so that the pups could only be reared if injections of oxytocin were given to the mothers twice daily. When, however, these posterior lobectomized rats became pregnant a second time, parturition was normal and the milk-ejection reflex was sufficiently restored for the rats to rear their litters without oxytocin being administered. The animals, however, continued to exhibit diabetes insipidus. Measurements of residual neurohypophysial tissue showed that hypertrophy of the neural stalk had occurred after posterior lobectomy.These findings are discussed in relation to recent studies on the site of formation and the liberation of posterior-pituitary hormone(s) after hypophysectomy.While the early experiments of Ott & Scott [1911], Schäfer [1913] and Gaines [1915] demonstrated that injections of posterior-pituitary extracts into lactating animals resulted in the ejection of milk, the effect was considered to be of pharmacological interest only. Turner & Slaughter in 1930 appear to have been the first to suggest a physiological role for the posterior pituitary in normal milk ejection, but it was not until 1941 that Ely & Petersen elaborated this theory and emphasized the importance of the milk-ejection reflex in the maintenance of full lactation. Direct evidence, how¬ ever, in support of this role of the neurohypophysis in lactation was somewhat scanty, and Macaulay [1951] in reviewing the literature concluded that there was insufficient evidence available to do any more than suggest that the neural lobe of the hypophysis participated in milk ejection. Within the last 4 years more direct evidence of the role of the neurohypophysis has been obtained. Of particular import¬ ance are the experiments of Cross & Harris [1952], who showed that interruption of the nerve connexions between the hypothalamus and the hypophysis (electrolytic lesions placed in the supraoptico-hypophysial tract) in the lactating rabbit caused a marked diminution in the quantity of milk obtained by the litter in standard suckling tests. If, however, the rabbit was injected with oxytocin the litter then obtained the normal quantity of milk. Studies on the effect on milk ejection of removal of the neural lobe have given somewhat discordant results. Smith [1932] observed that after removal of the posterior lobe normal parturition occurred in the rat and lactation, as evidenced by the growth of the pups, appeared normal or only slightly depressed. Houssay [1935] also reported that bitches could rear their young after 'neurohypophysectomy'. On the other hand, Harris & Jacobsohn [1952] and Cowie [quoted by Folley, 1952] observed that destruction of neural lobe function or removal of the lobe in lactating

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Section: Discussionsupporting

confidence: 65%

Section: Discussionmentioning

confidence: 99%

Lactation in the Rat After Hypophysial Posterior Lobectomy

Benson¹,

Cowie²

1956

Journal of Endocrinology

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“…This occurs in an environment in which astrocytes are lacking. In fact, after 30 days neu rosecretory neurons have recovered functionally to the ex tent that circulating levels of vasopressin are indistinguish able from those in intact controls [22][23][24]. When severance occurs within the hypothalamus, however, axon regenera tion is limited by astrocytic glial scar formation (unpu blished observations).…”

mentioning

confidence: 99%

“…When transected at the level of the median eminence or the hypophysial stalk, ax onal growth cones develop and establish new neurohemal contacts with the primary capillary plexus of the hypophy sial portal system which, together with pituicyte prolifera tion, eventually leads to the formation of a miniature neural lobe-like structure [13,20, 29, 30, 32]. Concurrent with this morphologic recovery is the reestablishment of near normal levels of hormone secretion and water balance [22][23][24]. When transected within the hypothalamus, however, neu rosecretory axons either do not regenerate [26] or they only regenerate to a rather limited extent [19] without concomi tant functional recovery.…”

mentioning

confidence: 99%

Peptidergic Neurosecretory Axons Regenerate into Sciatic Nerve Autografts in the Rat Hypothalamus

Hd¹,

Lf²,

Bellin³

1986

Neuroendocrinology

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Pieces of intact or degenerated sciatic nerves autografted into contact with transected neurosecretory axons within the hypothalamus were invaded by neurophysin-positive axons. With increasing time after grafting, increasing numbers of axons were present in both types of grafts, but grafts of degenerated sciatic nerves always contained more axons. At the fine-structural level typical neurosecretory as well as nonneurosecretory axons were usually associated with basal lamina-enclosed neurolemmocyte processes; occasional axons occurred among collagen fibrils or within basal lamina scaffolds. Profiles with the fine structural characteristics of axon terminals were present by 20 days after transplantation.

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“…In mammals, the transformation of the pituitary stalk into a functional neural lobe-like organ, after hypophysectomy, has been described by several authors (Stutinsky [1951(Stutinsky [ , 1952(Stutinsky [ , 1956, Billenslien and Leveque [1955], Lloyd and Pierog [1955], Benson and Cowie [1956], Moll [1957]). …”

Section: Introductionmentioning

confidence: 99%

Regeneration of the Neural Lobe of the Hypophysis After Extirpation of the Median Eminence in Rana Temporaria

Dierickx¹

1965

Cells Tissues Organs

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Studies of the Antidiuretic Activity of Blood and Hypothalamus of Hypophysectomized Rats

Cited by 23 publications

References 0 publications

Lactation in the Rat After Hypophysial Posterior Lobectomy

Lactation in the Rat After Hypophysial Posterior Lobectomy

Peptidergic Neurosecretory Axons Regenerate into Sciatic Nerve Autografts in the Rat Hypothalamus

Regeneration of the Neural Lobe of the Hypophysis After Extirpation of the Median Eminence in Rana Temporaria

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