Immunoreactive Prolactin Forms Colocalize with Vasopressin in Neurons of the Hypothalamic Paraventricular and Supraoptic Nuclei

Mejía, Salvador; Morales, M.A.; Zetina, M.E.; Escalera, Gonzálo Martínez de la; Clapp, Carmen

doi:10.1159/000127233

Cited by 38 publications

(31 citation statements)

References 32 publications

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“…There is also evidence that estrogen influences oxytocin and vasopressin gene expression in the hypothalamus of osmotically stimulated and lactating rats , and a functional estrogen response element has been located on the promoter region of the oxytocin gene (Mohr & Schmitz 1991). Furthermore, it has been shown that estrogen enhances the expression of peptides known to coexist with vasopressin in the same magnocellular neuron (Levin & Sawchenko 1993), a result that correlates with our present findings, since PRLs colocalize with vasopressin in magnocellular neurons from both the PVN and SON (Mejía et al 1997).…”

Section: Discussionsupporting

confidence: 91%

“…The present findings show that estrogen reduces the activity of neurohypophyseal enzymes, able to cleave 23 kDa PRL into a 16 kDa PRL fragment, a form of PRL that shares similar antigenic and biological determinants with neurohypophyseal 14 kDa PRL (Clapp et al 1994, López-Gómez et al 1995, Mejía et al 1997. Furthermore, this effect of estrogen on PRL-cleaving activity is not entirely unexpected.…”

Section: Discussionsupporting

confidence: 64%

“…RT-PCR confirmed and extended previous findings by showing the expression of PRL mRNA in the PVN, as previously reported (Clapp et al 1994), but also in the SON. Expression of PRL mRNA at both sites correlates with the presence of immunoreactive PRLs in magnocellular neurons from both hypothalamic nuclei (Clapp et al 1994, Mejía et al 1997. In the PVN and SON, PRL mRNA levels appeared to be associated with the hormonal status of the animals.…”

Section: Discussionmentioning

confidence: 85%

“…The translation of PRL mRNA in the hypothalamoneurohypophyseal system has been supported by the presence of immunoreactive and biologically active PRLs in magnocellular neurons of the PVN, SON and in their neurohypophyseal endings (Clapp et al 1994, López-Gómez et al 1995, Mejía et al 1997. These PRLs include variants of 23 and 14 kDa that have been determined both in intact and in hypophysectomized rats (Clapp et al 1994, Torner et al 1995.…”

Section: Discussionmentioning

confidence: 99%

“…PRL mRNA was identified in isolated PVN by the reverse transcription-polymerase chain reaction (RT-PCR), and PRL proteins of 23 and 14 kDa were detected within both the PVN and SON and in their axonal projections into the neurohypophysis (Clapp et al 1994). These PRLs were localized within secretory granules of vasopressin-containing cells (Mejía et al 1997).…”

Section: Introductionmentioning

confidence: 99%

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Changes in the expression of neurohypophyseal prolactins during the estrous cycle and after estrogen treatment

Torner¹,

Nava²,

Dueñas³

et al. 1999

Journal of Endocrinology

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Estrogens are recognized regulators of the expression of neurohypophyseal hormones and of anterior pituitary prolactin (PRL). Here we have investigated whether the levels of PRL mRNA and of 23 and 14 kDa PRL variants present in the hypothalamo-neurohypophyseal system change during the estrous cycle or in response to estrogen treatment. The reverse transcription polymerase chain reaction (RT-PCR) was performed to examine PRL mRNA expression in isolated paraventricular (PVN) and supraoptic (SON) hypothalamic nuclei. In both nuclei PRL mRNA levels appeared higher in cycling females than in male rats, with the highest level occurring at estrus. This increase may involve estrogen action, since estrogen administration to ovariectomized rats was associated with apparently higher PRL mRNA levels in both the PVN and SON. Expression of the PRL gene at these sites may occur via both transcriptional factor Pit-1-dependent and -independent mechanisms. RT-PCR detected the mRNA for Pit-1 in the PVN but only at estrus. The concentration of the 23 kDa immunoreactive PRL determined in the neurohypophysis was significantly higher during estrus and after estrogen treatment. However, no difference was detected in the levels of the neurohypophyseal 14 kDa PRL-like fragment along the estrous cycle nor after estrogen administration. This lack of parallelism between neurohypophyseal PRLs could relate to an estrogen-induced inhibition of the proteolysis of 23 kDa PRL at this site, since estrogen treatment reduced the activity of neurohypophyseal proteolytic enzymes able to cleave PRL. Altogether our results are consistent with estrogens having a stimulatory effect on PRL gene expression in the hypothalamo-neurohypophyseal system and a concomitant inhibitory action on PRL proteolysis at this site.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 64%

Section: Discussionmentioning

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Changes in the expression of neurohypophyseal prolactins during the estrous cycle and after estrogen treatment

Torner¹,

Nava²,

Dueñas³

et al. 1999

Journal of Endocrinology

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Estrogen receptor‐β, but not estrogen receptor‐α, is expressed in prolactin neurons of the female rat paraventricular and supraoptic nuclei: Comparison with other neuropeptides

Suzuki

Handa

2005

J of Comparative Neurology

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Estrogen receptor-alpha (ER-alpha) and ER-beta exhibit fine differences in their distributions in the rodent forebrain, and one such difference is observed in the paraventricular (PVN) and supraoptic (SON) nuclei. To investigate the functional significance of ER in these brain areas, we examined the neuropeptide characteristics of ER-expressing neurons in the PVN and SON of female rats by using dual-label immunocytochemistry. The distributions of ER-alpha immunoreactivity (ir) and ER-beta ir were nonoverlapping in the PVN and SON. Nuclear ER-alpha ir was found in a population of thyrotropin-releasing hormone (TRH)-expressing neurons in the PVN (5.93% +/- 1.20% SEM), but not in any other identified cell phenotype of the PVN and SON. The phenotype of neurons with the highest percentage expressing ER-beta was found to be prolactin (PRL) immunoreactive in both the parvocellular (84.95% +/- 4.11%) and the magnocellular (84.76% +/- 3.40%) parts of the PVN as well as the SON (87.57% +/- 4.64%). Similarly, most vasopressin-immunoreactive neurons were also ER-beta positive in the PVN (66.14% +/- 2.47%) and SON (72.42% +/- 4.51%). In contrast, although a high percentage of oxytocin (OXY) neurons coexpressed ER-beta in the PVN (84.39% +/- 2.99%), there was very little ER-beta/OXY colocalization in the SON. Low levels of corticotropin-releasing hormone neurons also expressed ER-beta ir in the PVN (12.57% +/- 1.99%), but there was no ER-beta colocalization with TRH. In summary, these findings further support the possibility of direct effects of estrogen on neuropeptide expression and implicate estrogen involvement in the regulation of various aspects of neuroendocrine function.

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Differential sensitivity of specific neuronal populations of the rat hypothalamus to prolactin action

Sapsford

Kokay

Östberg

et al. 2012

J of Comparative Neurology

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Prolactin stimulates dopamine release from neuroendocrine dopaminergic (NEDA) neurons in the hypothalamic arcuate nucleus (ARC) to maintain low levels of serum prolactin. Elevated prolactin levels during pregnancy and lactation may mediate actions in other hypothalamic regions such as the paraventricular nucleus (PVN) and rostral preoptic area (rPOA). We predicted that NEDA neurons would be more sensitive prolactin targets than neurons in other regions because they are required to regulate basal prolactin secretion. Moreover, differences in the accessibility of the ARC to prolactin in blood may influence the responsiveness of this population. Therefore, we compared prolactin-induced signaling in different hypothalamic neuronal populations following either systemic or intracerebroventricular (icv) prolactin administration. Phosphorylation of the signal transduction factor, STAT5 (pSTAT5), was used to identify prolactin-responsive neurons. In response to systemic prolactin, pSTAT5-labeled cells were widely observed in the ARC but absent from the rPOA and PVN. Many of these responsive cells in the ARC were identified as NEDA neurons. The lowest icv prolactin dose (10 ng) induced pSTAT5 in the ARC, but with higher doses (>500 ng) pSTAT5 was detected in numerous regions, including the rPOA and PVN. NEDA neurons were maximally labeled with nuclear pSTAT5 in response to 500 ng prolactin and appeared to be more sensitive than dopaminergic neurons in the rPOA. Subpopulations of oxytocin neurons in the hypothalamus were also found to be differentially sensitive to prolactin. These data suggest that differences in the accessibility of the arcuate nucleus to prolactin, together with intrinsic differences in the NEDA neurons, may facilitate homeostatic feedback regulation of prolactin release.

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Immunoreactive Prolactin Forms Colocalize with Vasopressin in Neurons of the Hypothalamic Paraventricular and Supraoptic Nuclei

Cited by 38 publications

References 32 publications

Changes in the expression of neurohypophyseal prolactins during the estrous cycle and after estrogen treatment

Changes in the expression of neurohypophyseal prolactins during the estrous cycle and after estrogen treatment

Estrogen receptor‐β, but not estrogen receptor‐α, is expressed in prolactin neurons of the female rat paraventricular and supraoptic nuclei: Comparison with other neuropeptides

Differential sensitivity of specific neuronal populations of the rat hypothalamus to prolactin action

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