Section of the Pituitary Stalk in the Rhesus Monkey

Antunes, JL; Louis, K M; Cogen, Philip H.; Ea, Zimmerman; Ferin, Michel

doi:10.1159/000122979

Cited by 22 publications

(6 citation statements)

References 18 publications

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“…This is in marked contrast to observations in both fetal sheep [ 19,20] and monkey [33] after stalk section, where degenerative changes in the cells of the pars distalis have been reported. Interruption of the vas cular supply of the pars distalis could well account for such changes in cell appearance.…”

Section: Morphological Aspectscontrasting

confidence: 99%

Hypothalamo-Pituitary Disconnection in the Fetal Sheep

Clarke²,

et al. 1990

Neuroendocrinology

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In this study we have applied the technique of hypothalamo-pituitary disconnection (HPD) to the fetal sheep at 108–112 days of gestation. The pituitary is surgically disconnected from the hypothalamus by the removal of the neural component of the median eminence above the level of the portal circulation. This procedure results in the complete disconnection of the pituitary from the hypothalamus. After HPD, the lactotroph response to the dopamine antagonist chlorpromazine was significantly reduced (p < 0.005) indicating the functional isolation of the pituitary gland from the hypothalamus. The increase in plasma prolactin in response to exogenous thyrotrophin-releasing factor was maintained following HPD. HPD resulted in the complete atrophy of the pars nervosa. At 132–135 days of gestation after HPD there was no change in the volume or appearance of the pars distalis; small infarcts were observed in the pars distalis of some HPD fetuses, but these occupied less than 1% of the volume of the anterior lobe of the pituitary. There was a significant increase (p < 0.05) in the volume of the pars intermedia after HPD. Gestation was prolonged for at least 8 days beyond normal term following HPD, indicating that the processes integral to the initiation of parturition at term had been disrupted. We conclude that HPD provides a good in vivo model for the investigation of the activity of the isolated pituitary gland, and for the examination of the role of neuroendocrine mechanisms in fetal sheep development in the latter third of gestation.

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Section: Morphological Aspectscontrasting

confidence: 99%

Hypothalamo-Pituitary Disconnection in the Fetal Sheep

Clarke²,

et al. 1990

Neuroendocrinology

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“…Furthermore, it has been shown that the number of immunostained corticotrophs, gonadotrophs and somatotrophs did not change up to 3 weeks after veri fied pituitary stalk sections in rhesus monkeys. In agree ment with our work, a two-to fivefold increase in the num ber of immunostained mammotrophs was estimated in these monkeys, although this was not quantitated [1], Final ly, Tougarci et al [34) have shown that immunostained go nadotrophs do not decrease dramatically in number, even after 26 days in culture.…”

Section: Discussionsupporting

confidence: 88%

Mammotroph and Gonadotroph Volume Percentage in the Rat Anterior Pituitary after Lesion of the Medial Basal Hypothalamus

Cronin

Cheung²,

Weiner

et al. 1982

Neuroendocrinology

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A lesion of the medial basal hypothalamus (MBH) results in enhanced secretion of prolactin and reduced release of the other hormones from the anterior pituitary. We measured the volume percentage of the prolactin-secreting mammotrophs, stained immunocytochemically, under several experimental conditions to assess the morphological correlate of the high secretion of prolactin. In addition, gonadotrophs were stained both tinctorially with the periodic acid-Schiff reagent and immunocytochemically with antibodies to luteinizing hormone. Anterior pituitaries were studied from female rats which were:(1) cycling, (2) ovariectomized for 2 weeks, (3) ovariectomized for 2 weeks with a lesion of the MBH for 1. 14 or 21 days. The volume percentage of mammotrophs and gonadotrophs in the lateral, central and middle fields of the anterior pituitary was determined and this measurement was expressed relative to endocrine cellular area so that vascular space and necrotic regions would not be included in the assessment. Ovariectomy significantly decreased mammotroph and increased gonadotroph volume percentage when compared to the intact animal. MBH lesions had the opposite effect. At 14 and 21 days after a lesion, the volume percentage of mammotrophs was significantly greater than in the intact rat, while the volume percentage of gonadotrophs was identical to that observed in the intact rat. These data suggest that the elimination of the prolactin-inhibitory hormone(s) of the MBH results in hypertrophy and/or hyperplasia of mammotrophs. This effect occurs in the absence of ovarian steroids and may be of importance in the induction of prolactin-secreting pituitary adenomas. The data also support the hypothesis that destruction of gonadotropin-releasing hormone neuron terminals countermands the hypertrophy of gonadotrophs induced by ovariectomy.

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“…The remaining 8 monkeys had regular menstrual cycles: stalk section was performed in 5 of these animals during the early follicular phase (days [3][4][5][6][7][8] and in the 3 others at the time of the midcycle luteinizing hormone surge. Initial sedation was obtained with phencyclidine HCI (Sernylan®, 6-12 mg i.m.).…”

Section: Surgical Proceduresmentioning

confidence: 99%

“…Methods and results of further mor phological investigation are described in an accompanying paper [3].…”

Section: Endocrine Follow-up Am! Pitnitary Challenge Testsmentioning

confidence: 99%

Section of the Pituitry Stalk in the Rhesus Monkey

et al. 1980

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The effects of pituitary stalk section on anterior pituitary secretion were studied in 20 female rhesus monkeys. Vascular connections between the hypothalamus and the pituitary gland were permanently interrupted in all but 4 animals. Prolactin levels rose rapidly and remained significantly elevated in all effectively stalk-sectioned animals for as long as the observation period (up to 3 years). Only smaller and transient elevations of prolactin were seen in the animals in which revascularization of the anterior pituitary gland had occurred. Growth hormone and cortisol were significantly decreased after stalk section, and were not released by insulin. Radioimmunoassayable luteinizing hormone (LH) levels decreased following surgery and, by bioassay, LH became undetectable within 5 weeks after stalk section, indicating that gonadotropin-releasing hormone is essential for the viability of the gonadotrope. The results indicate that plasma prolactin concentrations can be used to monitor completeness of pituitary gland isolation from direct hypothalamic influence. Stalk-sectioned monkeys provide good models to study direct pituitary effects of various hormones or drugs.

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Section of the Pituitary Stalk in the Rhesus Monkey

Cited by 22 publications

References 18 publications

Hypothalamo-Pituitary Disconnection in the Fetal Sheep

Hypothalamo-Pituitary Disconnection in the Fetal Sheep

Mammotroph and Gonadotroph Volume Percentage in the Rat Anterior Pituitary after Lesion of the Medial Basal Hypothalamus

Section of the Pituitry Stalk in the Rhesus Monkey

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