THE REORGANIZATION OF THE NEUROHYPOPHYSEAL STALK FOLLOWING HYPOPHYSECTOMY IN THE RAT<sup>1</sup>

Billenstien, Dorothy C.; Leveque, Theodore F.

doi:10.1210/endo-56-6-704

Cited by 109 publications

(32 citation statements)

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“…The reorganization of neurohypophyseal hormone-pro ducing neurons has been studied following SS [3], hypophysectomy [5], and LOBEX [19]. In spite of a decrease in the number of the magnocellular neurons in the hypothalamus due to retrograde degeneration [24], an increase of 'neurosecretory material" in the hypothalamus and proxi mal end of the pituitary stalk has been reported [5], Yet, while some investigators reported that OXY levels in the hypothalamus increase following hypophysectomy [9] or LOBEX [14], others have seen no changes [34], In the pre sent study, OXY levels in the MBH increased more than 100-fold 2 weeks after SS.…”

Section: Discussionmentioning

confidence: 99%

“…In spite of a decrease in the number of the magnocellular neurons in the hypothalamus due to retrograde degeneration [24], an increase of 'neurosecretory material" in the hypothalamus and proxi mal end of the pituitary stalk has been reported [5], Yet, while some investigators reported that OXY levels in the hypothalamus increase following hypophysectomy [9] or LOBEX [14], others have seen no changes [34], In the pre sent study, OXY levels in the MBH increased more than 100-fold 2 weeks after SS. This elevation may be due to an accumulation of secretory vesicles containing OXY in pre existing and/or newly formed nerve endings in the MBH, as well as to increased OXY synthesis [34], DA is well established as the major physiological inhib itor of PRL secretion [4], Tuberoinfundibular dopaminergic (TIDA) neurons have cell bodies in the arcuate nucleus and nerve terminals in the median eminence which are in close proximity to precapillary spaces of the long portal vessels.…”

Section: Discussionmentioning

confidence: 99%

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Differential Effects of Pituitary Stalk-Section on Posterior Pituitary and Hypothalamic Contents of Prolactin-Releasing Factor, Oxytocin, Dopamine and Beta-Endorphin

Hyde¹,

Murai²,

Ben‐Jonathan³

1988

Neuroendocrinology

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We have recently shown that the posterior pituitary (neurointermediate lobe) contains a potent prolactin (PRL)-releasing factor (PRF) which is distinct from known PRL secretagogues. Posterior pituitary PRF appears to be a small peptide of an unknown cellular origin. Using pituitary stalk-sectioned (SS) male rats, the objectives of this study were: (1) to determine if PRF is transported from the hypothalamus or is synthesized within the pituitary gland, and (2) to compare changes in PRF activity with alterations in the posterior pituitary content of β-endorphin (β-END), oxytocin (OXY), and dopamine (DA). One or two weeks following pituitary SS or sham surgery (SHAM), acid extracts of the posterior pituitary and medial basal hypothalamus (MBH) were analyzed for their hormone content. PRF activity was assessed by determining the stimulation of PRL secretion from perifused anterior pituitary cells, DA was measured by HPLC, and OXY and β-END levels were determined by RIAs. OXY and DA concentrations in the posterior pituitary were reduced more than 95% at both 1 and 2 weeks after SS. PRF activity in the posterior pituitary was significantly reduced by 75 and 90%, 1 and 2 weeks after SS, respectively. In contrast, β-END levels in the posterior pituitary at these times increased 20 and 60%, as compared to SHAM rats. Unlike the posterior pituitary, OXY levels in the MBH increased 123% 1 week following SS, and 1,260% at 2 weeks. These increases may reflect the accumulation of OXY-containing secretory vesicles in the severed nerves. DA concentrations in the MBH showed a biphasic pattern. DA levels were initially decreased by 70%, and then increased, but remained 30% below SHAM levels. The reason for these alterations in DA levels is not clear. It is concluded that: (1) similar to OXY and DA, but unlike β-END, PRF is likely transported from the hypothalamus to the posterior pituitary, and (2) the low levels of PRF activity in the MBH suggest that PRF may be synthesized as a biologically inactive precursor, the amount of PRF in the MBH is too low to detect, or inhibitors of PRL secretion mask the PRF activity.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Differential Effects of Pituitary Stalk-Section on Posterior Pituitary and Hypothalamic Contents of Prolactin-Releasing Factor, Oxytocin, Dopamine and Beta-Endorphin

Hyde¹,

Murai²,

Ben‐Jonathan³

1988

Neuroendocrinology

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“…has been described. It is generally assumed that these cardiovascular and renal changes reflect removal of the influence of the anterior rather than posterior pituitary hormones, secretion of neurohypophysial hormones being at least partially restored from the cut end ofthe pituitary stalk a few days after surgery (Billenstein & Levique, 1955).…”

mentioning

confidence: 99%

The influence of neurohypophysial hormones on renal function in the acutely hypophysectomized rat.

Balment¹,

Brimble²,

Forsling³

et al. 1986

The Journal of Physiology

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1. Renal function and the effect of neurohypophysial hormone replacement was investigated in anaesthetized, acutely hypophysectomized, male rats. 2. Although urine production was only slightly lower over the 8 h post-operative study period in hypophysectomized rats, sodium excretion was greatly depressed reaching only 3.5 +/- 1.4 mumol/min compared with a peak of 13.2 +/- 1.0 mumol/min in intact animals. 3. In association with a decline in mean arterial blood pressure, glomerular filtration rate in hypophysectomized rats fell to 2.1 +/- 0.2 ml/min 8 h after operation by comparison with a mean rate in intact rats of 3.2 +/- 0.2 ml/min. 4. Plasma corticosterone levels were much lower in hypophysectomized (4 +/- 2 ng/ml) than in intact (36 +/- 4 ng/ml) rats, plasma aldosterone was reduced to a lesser extent (0.41 +/- 0.08 compared with 0.76 +/- 0.04 ng/ml). While oxytocin was not detectable in hypophysectomized rat plasma, trace levels of vasopressin (0.16 +/- 0.04 mu u./ml) were found. In intact unanaesthetized rats basal plasma levels of oxytocin were 0.32 +/- 0.13 mu u./ml and vasopressin were 0.85 +/- 0.19 mu u./ml. 5. Administration of oxytocin at 150 mu u./min, which produced plasma hormone levels (24.0 +/- 2.5 mu u./ml) greatly in excess of basal concentrations, increased renal sodium excretion but did not alter urine flow. Oxytocin administration at the lower rate of 15 mu u./min producing plasma hormone levels of 2.60 +/- 0.1 mu u./ml, did not alter renal sodium excretion. 6. Arginine vasopressin administered at 12 mu u./min induced plasma hormone levels of 1.54 +/- 0.09 mu u./ml and produced a large antidiuresis and small increase in the rate of sodium excretion. 7. The natriuretic response to vasopressin was potentiated by concurrent administration of oxytocin at 15 mu u./min. The peak sodium excretion of 5.8 +/- 1.0 mumol/min, however, remained well below that seen in intact rats. 8. It is concluded that, as restoration of posterior pituitary hormones at or above the physiological range only partially restored sodium excretion, the absence of anterior pituitary factors may also contribute directly or indirectly to the renal sodium retention of the hypophysectomized rat.

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“…However, in hypophysectomized animals newly formed tissue like that of the posterior lobe at the cut-end of the hypophysial stalk and the proliferation of neurosecretory axons in the external layer of the median eminence have been detected histologically by many authors applying Gomori staining (SCHARRER and WITTENSTEIN, 1952;BILLENSTIEN and LEVEQUE, 1955;GAUP and SPATZ, 1955;STUTINSKY, 1955;MOLL, 1957;BECK and DANIEL, 1960;ROTHBALLER and SKORYNA, 1960;SATHYANESAN and GORBMAN, 1965;ADAMS et al, 1969;BECK et al, 1969). Several authors also observed that these proliferated neurosecretory axons extend deeply into the pars tuberalis (BECK and DANIEL, 1960;SATHYANESAN and GORBMAN, 1965;ADAMS et al, 1969;BECK et al, 1969;DANIEL and PRICHARD, 1970).…”

Section: Discussionmentioning

confidence: 99%

Ultrastructural Changes of the Pars Tuberalis and Median Eminence of Rats Following Hypophysectomy

Kotsu

Daikoku

1972

Arch. Histol. Jap., Arch. Histol. Jpn

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Summary.The pars tuberalis of the hypophysis and the external layer of the median eminence were studied by electron microscopy using hypophysectomized rats. Twenty dayold and adult rats were hypophysectomized and examined at various intervals (from 10 to 150 days) afterwards.Several hypophysectomized adult rats were adrenalectomized and examined 3 days later.Ten days after hypophysectomy, the external layer of the median eminence indicated

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THE REORGANIZATION OF THE NEUROHYPOPHYSEAL STALK FOLLOWING HYPOPHYSECTOMY IN THE RAT¹

Cited by 109 publications

References 0 publications

Differential Effects of Pituitary Stalk-Section on Posterior Pituitary and Hypothalamic Contents of Prolactin-Releasing Factor, Oxytocin, Dopamine and Beta-Endorphin

Differential Effects of Pituitary Stalk-Section on Posterior Pituitary and Hypothalamic Contents of Prolactin-Releasing Factor, Oxytocin, Dopamine and Beta-Endorphin

The influence of neurohypophysial hormones on renal function in the acutely hypophysectomized rat.

Ultrastructural Changes of the Pars Tuberalis and Median Eminence of Rats Following Hypophysectomy

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THE REORGANIZATION OF THE NEUROHYPOPHYSEAL STALK FOLLOWING HYPOPHYSECTOMY IN THE RAT1

Cited by 109 publications

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Differential Effects of Pituitary Stalk-Section on Posterior Pituitary and Hypothalamic Contents of Prolactin-Releasing Factor, Oxytocin, Dopamine and Beta-Endorphin

Differential Effects of Pituitary Stalk-Section on Posterior Pituitary and Hypothalamic Contents of Prolactin-Releasing Factor, Oxytocin, Dopamine and Beta-Endorphin

The influence of neurohypophysial hormones on renal function in the acutely hypophysectomized rat.

Ultrastructural Changes of the Pars Tuberalis and Median Eminence of Rats Following Hypophysectomy

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THE REORGANIZATION OF THE NEUROHYPOPHYSEAL STALK FOLLOWING HYPOPHYSECTOMY IN THE RAT¹