Adenohypophysis Has an Inherent Property for Pulsatile Prolactin Secretion

Shin, Seon H.; Reifel, C. W.

doi:10.1159/000123146

Cited by 52 publications

(26 citation statements)

References 18 publications

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“…Based on critical revaluation of older data and jetlag studies, Van Cauter and coworkers [15,16] suggested that human prolactin is not entirely entrained with sleep. A study in rats also showed that an intrinsic periodicity in prolactin secretion can be found in transplanted pituitaries [17]. In our patients who were kept under a constant day-light schedule, a nocturnal surge of prolactin was present, although with reduced amplitude, for months after total disruption of the physiological sleep activity.…”

Section: Discussionsupporting

confidence: 69%

“…Among the others, prolactin and somatotropin have long been known to show episodic peaks of secretion superimposed upon a significant 24-hour rhythm mainly determined by a distinct nocturnal elevation [1][2][3][4][5][6][7][8][9][10][11][12][13][14], Data from the literature clearly point to a relation of the nocturnal surge of somatotropin to the onset of sleep [4][5][6][7][8][9][10][11][12][13][14], The nocturnal rise of prolactin occurs in later hours and has also been shown to shift with the sleep period [1][2][3]. However, the sleep entrainment of the nocturnal prolactin surge has been questioned both in humans [15,16] and in rats [17].…”

Section: Introductionmentioning

confidence: 99%

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Dissociated 24-Hour Patterns of Somatotropin and Prolactin in Fatal Familial Insomnia

et al. 1995

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To assess the changes in the 24-hour profiles of serum somatotropin and prolactin levels during total disruption of the sleep/wake cycle sustained over several months, we studied 2 subjects affected by fatal familial insomnia, a rare disease characterized by selective thalamic degeneration that causes chronic sleep loss. Under standardized conditions and polysomnographic control, the patients underwent repeated 24-hour study sessions covering the entire clinical course of the disease. Hormones were assayed at 30-min intervals. Four healthy volunteers were used as controls. A sleep/wake cycle was always absent in fatal familial insomnia. Serum somatotropin and prolactin concentrations never exceeded the normal range of variation. The nocturnal elevation of somatotropin disappeared simultaneously with sleep loss, whereas a significant 24-hour component of variations in serum prolactin levels was present for months after total disruption of the sleep/wake cycle, with normally placed nocturnal acrophases. Complete obliteration of the 24-hour component was achieved for prolactin only in the advanced stages, through a progressive decrease in 24-hour amplitude of variation. Selective and progressive degeneration of the mediodorsal and anterior ventral nuclei of the thalamus causes an early obliteration of the 24-hour rhythm of somatotropin and a later disappearance of circadian prolactin rhythmicity. The persistence of a significant circadian rhythm for months after total disruption of the sleep/wake cycle indicates that prolactin rhythmicity is not exclusively sleep-entrained.

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Section: Discussionsupporting

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Dissociated 24-Hour Patterns of Somatotropin and Prolactin in Fatal Familial Insomnia

et al. 1995

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“…Another consideration that some prolactin pulses may be generated semiautonomously within the pituitary gland by as yet incompletely characterized mechanisms, is suggested by studies of perifused or transplanted pituitary glands (21,22). However, precisely how such intraglandular-triggered prolactin secretory bursts could be coupled to LH release episodes is not clear.…”

Section: Figmentioning

confidence: 99%

Random and Non‐Random Coincidence Between Luteinizing Hormone Peaks and Follicle‐Stimulating Hormone, Alpha Subunit, Prolactin and Gonadotropin‐Releasing Hormone ulsations

Veldhuis

Iranmanesh

Clarke

et al. 1989

J Neuroendocrinology

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We have examined the co-pulsatility of luteinizing hormone (LH) and prolactin, LH and follicle-stimulating hormone (FSH), and LH and cx subunit in normal men. We tested whether the degree of physiologically observed co-pulsatility (peak coincidence) significantly exceeded expected random concordance between independently pulsating hormone series. To this end, computer simulations were used to create synthetic endocrine time series pulsating randomly and independently at known frequencies. Resultant predictions of the mean, variance and probability distribution of the number of randomly coincident peaks permitted us to test the null hypothesis that physiologically observed hormone co-pulsatility was due to chance peak associations alone. Physiological observations were made in 33 normal men and in six ovariectomized ewes subjected to combined hypothalamo-pituitary and jugular venous catheterization. The following salient results were obtained: 1) random peak coincidence rates between independently pulsating hormone series were substantial at high pulse frequencies, but such random rates were significantly exceeded in the case of gonadotropin-releasing hormone and LH peaks (P

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“…Most of the prolactin present in the cir culation under these circumstances should be derived from the ectopic gland [24] which is not under the tonic hypothalamic inhibition, so that an increased secretion rate of prolactin from these cells might by responsible for increased circulating levels of the hormone. This suggests that the pulsatile pattern of peripheral prolactin in pitu itary-grafted rats is due to the persistence of the secretory pulsatile behavior of the lactotrophs in the ectopic gland [19]. The increase in the number of lactotrophs in the ectopic gland might also account for the higher mean val ues of the hormone during the studied period, and the number of these cells increased immediately after pitu itary grafting [25], Administration of CyA to sham-operated rats induced alterations in the pulsatile pattern of prolactin release which resemble the effects of pituitary grafting: dimin ished frequency, increased amplitude and duration of the peaks.…”

Section: Discussionmentioning

confidence: 98%

“…One of them may originate in the hypothala mus, and depend on dopaminergic activity [18] and the other is present in the pituitary and depends on the inher ent pulsatile property of the lactotrophs [19].…”

Section: Discussionmentioning

confidence: 99%

Cyclosporine Modifies the Pulsatile Secretory Patterns of Prolactin and Luteinizing Hormone in Normal and Pituitary-Grafted Female Rats

Esquifino

Marcó²,

Lafuente³

1994

Neuroendocrinology

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This study was designed to examine whether cyclosporine (CyA) acts on the endocrine system by modifying the pulsatile secretion pattern of prolactin and LH. Both pituitary-grafted and sham-operated rats were submitted to a subcutaneous vehicle or CyA (5 mg/kg) treatment daily for 10 days beginning on the day of surgery. Pituitary grafting and/or CyA administration changed the pulsatile pattern of prolactin observed in sham-operated animals. The mean values of serum prolactin were significantly increased by pituitary grafting and the treatment with CyA further increased them. The mean half-life of prolactin was significantly increased in pituitary-grafted rats and was not changed by CyA administration, although it was decreased in sham-operated rats. The frequency of prolactin pulses was significantly decreased in pituitary-grafted as compared to sham-operated controls and was not further modified by CyA administration. However, in sham-operated rats a significant decrease of this parameter was observed. Duration of the prolactin peaks was significantly increased by pituitary grafting, and was not modified by CyA administration in any of the groups studied. The absolute amplitude of the prolactin peaks was significantly increased in pituitary-grafted as compared to sham-operated animals, and the treatment with CyA further increased this parameter in both groups. Mean values of LH were significantly increased in pituitary-grafted as compared to control rats. CyA administration significantly increased LH levels in sham-operated rats and decreased them in pituitary-grafted animals. The mean half-life, the pulse frequency and the duration of LH peaks were not modified by either pituitary grafting or CyA administration. The absolute amplitude of LH peaks was significantly increased in pituitary-grafted animals as compared to the sham-operated group. Cy administration increased the absolute amplitude of LH peaks in sham-operated and reduced it in pituitary-grafted animals. The data suggest that CyA might act by modifying the pulsatile secretory patterns of prolactin and LH.

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Adenohypophysis Has an Inherent Property for Pulsatile Prolactin Secretion

Cited by 52 publications

References 18 publications

Dissociated 24-Hour Patterns of Somatotropin and Prolactin in Fatal Familial Insomnia

Dissociated 24-Hour Patterns of Somatotropin and Prolactin in Fatal Familial Insomnia

Random and Non‐Random Coincidence Between Luteinizing Hormone Peaks and Follicle‐Stimulating Hormone, Alpha Subunit, Prolactin and Gonadotropin‐Releasing Hormone ulsations

Cyclosporine Modifies the Pulsatile Secretory Patterns of Prolactin and Luteinizing Hormone in Normal and Pituitary-Grafted Female Rats

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