Localization of Vasoactive Intestinal Polypeptide Receptor 1 (VPAC1) in Hypothalamic Neuroendocrine Oxytocin Neurons; A Potential Role in Circadian Prolactin Secretion
Prolactin (PRL) is a versatile hormone and serves a broad variety of physiological functions besides lactation. The release of PRL from lactotrophs in the pituitary has in rodents been shown to be released with a circadian pattern depending on the physiological state of the animal. The circadian rel...
| Main Authors: | , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Frontiers Media S.A.
2020-10-01
|
| Series: | Frontiers in Neuroanatomy |
| Subjects: | |
| Online Access: | https://www.frontiersin.org/articles/10.3389/fnana.2020.579466/full |
| _version_ | 1818404033280344064 |
|---|---|
| author | Ida Stangerup Jens Hannibal |
| author_facet | Ida Stangerup Jens Hannibal |
| author_sort | Ida Stangerup |
| collection | DOAJ |
| description | Prolactin (PRL) is a versatile hormone and serves a broad variety of physiological functions besides lactation. The release of PRL from lactotrophs in the pituitary has in rodents been shown to be released with a circadian pattern depending on the physiological state of the animal. The circadian release of PRL seems to be complex involving tonic inhibition by dopamine (DA) neurons on lactotrophs and one or even several releasing factors. Because of the circadian releasing pattern of PRL, neurons in the suprachiasmatic nucleus (SCN), “the brain clock,” and especially the neurons expressing neuropeptide vasoactive intestinal polypeptide (VIP), have been suggested to be involved in the circadian regulation of PRL. In the present study, we used fluorescence immunohistochemistry, in situ hybridization histochemistry, confocal microscopy, three-dimensional reconstruction, and highly specific antibodies to visualize the occurrence of VIP receptors 1 and 2 (VPAC1 and VPAC2) in mouse brain hypothalamic sections stained in combination with VIP, oxytocin (OXT), arginine vasopressin (AVP), and DA (tyrosine hydroxylase, TH). We demonstrated that VIP fibers most likely originating from the ventral part of the SCN project to OXT neurons in the magnocellular part of the paraventricular nucleus (PVN). In the PVN, VIP fibers were found in close apposition to OXT neuron exclusively expressing the VPAC1 receptor. Furthermore, we demonstrate that neither OXT neurons nor TH or AVP neurons were expressing the VPAC2 receptor. VPAC1 receptor expression was also found on blood vessels but not in neurons expressing AVP or TH. These findings suggest that VIP signaling from the SCN does not directly target DA neurons involved in PRL secretion. Furthermore, the findings support the notion that VIP from neurons in the SCN could regulate circadian release of OXT in the posterior pituitary or modulate OXT neurons as a releasing factor involved in the circadian regulation of PRL from pituitary lactotrophs. |
| first_indexed | 2024-12-14T08:33:43Z |
| format | Article |
| id | doaj.art-2c9f62606c07415a860a77048585dcfd |
| institution | Directory Open Access Journal |
| issn | 1662-5129 |
| language | English |
| last_indexed | 2024-12-14T08:33:43Z |
| publishDate | 2020-10-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Neuroanatomy |
| spelling | doaj.art-2c9f62606c07415a860a77048585dcfd2022-12-21T23:09:27ZengFrontiers Media S.A.Frontiers in Neuroanatomy1662-51292020-10-011410.3389/fnana.2020.579466579466Localization of Vasoactive Intestinal Polypeptide Receptor 1 (VPAC1) in Hypothalamic Neuroendocrine Oxytocin Neurons; A Potential Role in Circadian Prolactin SecretionIda StangerupJens HannibalProlactin (PRL) is a versatile hormone and serves a broad variety of physiological functions besides lactation. The release of PRL from lactotrophs in the pituitary has in rodents been shown to be released with a circadian pattern depending on the physiological state of the animal. The circadian release of PRL seems to be complex involving tonic inhibition by dopamine (DA) neurons on lactotrophs and one or even several releasing factors. Because of the circadian releasing pattern of PRL, neurons in the suprachiasmatic nucleus (SCN), “the brain clock,” and especially the neurons expressing neuropeptide vasoactive intestinal polypeptide (VIP), have been suggested to be involved in the circadian regulation of PRL. In the present study, we used fluorescence immunohistochemistry, in situ hybridization histochemistry, confocal microscopy, three-dimensional reconstruction, and highly specific antibodies to visualize the occurrence of VIP receptors 1 and 2 (VPAC1 and VPAC2) in mouse brain hypothalamic sections stained in combination with VIP, oxytocin (OXT), arginine vasopressin (AVP), and DA (tyrosine hydroxylase, TH). We demonstrated that VIP fibers most likely originating from the ventral part of the SCN project to OXT neurons in the magnocellular part of the paraventricular nucleus (PVN). In the PVN, VIP fibers were found in close apposition to OXT neuron exclusively expressing the VPAC1 receptor. Furthermore, we demonstrate that neither OXT neurons nor TH or AVP neurons were expressing the VPAC2 receptor. VPAC1 receptor expression was also found on blood vessels but not in neurons expressing AVP or TH. These findings suggest that VIP signaling from the SCN does not directly target DA neurons involved in PRL secretion. Furthermore, the findings support the notion that VIP from neurons in the SCN could regulate circadian release of OXT in the posterior pituitary or modulate OXT neurons as a releasing factor involved in the circadian regulation of PRL from pituitary lactotrophs.https://www.frontiersin.org/articles/10.3389/fnana.2020.579466/fullprolactinoxytocindopaminereleasing factorparaventricular nucleusVPAC1 |
| spellingShingle | Ida Stangerup Jens Hannibal Localization of Vasoactive Intestinal Polypeptide Receptor 1 (VPAC1) in Hypothalamic Neuroendocrine Oxytocin Neurons; A Potential Role in Circadian Prolactin Secretion Frontiers in Neuroanatomy prolactin oxytocin dopamine releasing factor paraventricular nucleus VPAC1 |
| title | Localization of Vasoactive Intestinal Polypeptide Receptor 1 (VPAC1) in Hypothalamic Neuroendocrine Oxytocin Neurons; A Potential Role in Circadian Prolactin Secretion |
| title_full | Localization of Vasoactive Intestinal Polypeptide Receptor 1 (VPAC1) in Hypothalamic Neuroendocrine Oxytocin Neurons; A Potential Role in Circadian Prolactin Secretion |
| title_fullStr | Localization of Vasoactive Intestinal Polypeptide Receptor 1 (VPAC1) in Hypothalamic Neuroendocrine Oxytocin Neurons; A Potential Role in Circadian Prolactin Secretion |
| title_full_unstemmed | Localization of Vasoactive Intestinal Polypeptide Receptor 1 (VPAC1) in Hypothalamic Neuroendocrine Oxytocin Neurons; A Potential Role in Circadian Prolactin Secretion |
| title_short | Localization of Vasoactive Intestinal Polypeptide Receptor 1 (VPAC1) in Hypothalamic Neuroendocrine Oxytocin Neurons; A Potential Role in Circadian Prolactin Secretion |
| title_sort | localization of vasoactive intestinal polypeptide receptor 1 vpac1 in hypothalamic neuroendocrine oxytocin neurons a potential role in circadian prolactin secretion |
| topic | prolactin oxytocin dopamine releasing factor paraventricular nucleus VPAC1 |
| url | https://www.frontiersin.org/articles/10.3389/fnana.2020.579466/full |
| work_keys_str_mv | AT idastangerup localizationofvasoactiveintestinalpolypeptidereceptor1vpac1inhypothalamicneuroendocrineoxytocinneuronsapotentialroleincircadianprolactinsecretion AT jenshannibal localizationofvasoactiveintestinalpolypeptidereceptor1vpac1inhypothalamicneuroendocrineoxytocinneuronsapotentialroleincircadianprolactinsecretion |