Endocrine - Hypothalamus Development: Difference between revisions
Line 153: | Line 153: | ||
===Supraoptic Nucleus=== | ===Supraoptic Nucleus=== | ||
(SON) Arginine vasopressin (AVP) and oxytocin synthesis and released in the posterior pituitary. | (SON) Arginine vasopressin (AVP) and oxytocin (OT) synthesis and released in the posterior pituitary. These 2 hormones differ only in 2 amino acids in positions 3 and 8. | ||
* Arginine vasopressin (AVP) peptide hormone | * '''Arginine vasopressin''' (AVP) peptide hormone (9aa, nonapeptide) | ||
* synthesized as inactive preprohormone | * synthesized as inactive preprohormone | ||
* regulates blood volume and pressure acting on the kidney and heart | * regulates blood volume and pressure acting on the kidney and heart | ||
* Increased osmolality, due to blood volume reduction, increases AVP secretion. | * Increased osmolality, due to blood volume reduction, increases AVP secretion. | ||
* '''Oxytocin''' (OT) peptide hormone (9aa, nonapeptide) | |||
* mainly produced in hypothalamic magnocellular neurons | |||
* regulates female reproductive pregnancy-associated changes | |||
* acts on one type of OT receptor (OTR) | |||
* hormone is a non-glycosylated protein undergoes an initial cleavage by the convertase magnolysin (EC 3.4.24.62) to OT-Gly-Lys-Arg (OT-GKR). | |||
* additional processing produces other OT extended molecules: OT-Gly-Lys (OT-GK) and OT-Gly (OT-G, OT-X). | |||
* OT-G is converted by an α-amidating enzyme to C-amidated nonapeptide which is released into the circulation | |||
* may have a role in fetal heart growth | |||
Abnormalities: diabetes insipidus (vasopressin deficiency), syndrome of inappropriate antidiuresis (vasopressin excess) | Abnormalities: diabetes insipidus (vasopressin deficiency), syndrome of inappropriate antidiuresis (vasopressin excess) | ||
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===Paraventricular Nucleus=== | ===Paraventricular Nucleus=== | ||
(PVN) | (PVN) Arginine vasopressin (AVP) and oxytocin synthesis and released in the posterior pituitary. These 2 hormones differ only in 2 amino acids in positions 3 and 8. | ||
* Oxytocin peptide hormone | |||
* mainly produced in hypothalamic magnocellular neurons | |||
:'''Links''': [http://www.ncbi.nlm.nih.gov/books?term=Paraventricular%20Nucleus Search Bookshelf] | :'''Links''': [http://www.ncbi.nlm.nih.gov/books?term=Paraventricular%20Nucleus Search Bookshelf] |
Revision as of 11:48, 20 December 2010
Introduction
The hypothalamus has a key role in regulating the nearby pituitary and peripheral endocrine organ functions. This neural region therefore is associated with hormonally related behaviour (anger and sexual activity), homeostatic regulation (blood pressure, heart rate, appetite, and temperature) and functions that relate to both (puberty, reproductive cycles, and lactation).
In the early embryo, neuroectoderm of the forebrain (prosenecephalon) primary brain vesicle divides to form two secondary brain vesicles, telencephalon (endbrain, cortex) and diencephalon. From the diencephalon ventro-lateral wall, intermediate zone proliferation generates the primordial hypothalamus. Hypothalamus development also occurs differentially in male and female embryos, described as part of neural sexual dimorphism.
In the adult, large neurosecretory cells of the supraoptic nucleus (SON) and the paraventricular nucleus (PVN) project to the neurohypophysis from the hypothalamus. Other key nuclei within the hypothalamus include the sexually dimorphic nucleus (SDN, intermediate nucleus, INAH-1), suprachiasmatic nucleus (SCN) and tuberal lateral nucleus (NTL).
| Category:Hypothalamus | Lecture - Early Neural Development | Lecture - Late Neural Development | Lecture - Head Development | original page
Some Recent Findings
|
Hypothalamus Endocrine Axes
HPG Axis
Hypothalamus - Pituitary - Gonad endocrine axis.
This cartoon shows the Hypothalamus - Pituitary - Gonad endocrine axis.
The arrows indicate how each of these endocrine organs interact and regulate each others secretions through endocrine feedback mechanisms. |
HPA Axis
Hypothalamus - Pituitary - Adrenal endocrine axis.
HPT Axis
Hypothalamus - Pituitary - Thyroid endocrine axis.
Development Overview
Diencephalon region, shown by optic stalk (Stage 13) |
Late embryonic hypothalamus (Stage 22) |
Early fetal human brain (3 months, from a model by Wilhelm His) |
- Neuroectoderm - prosenecephalon then diencephalon
- ventro-lateral wall intermediate zone proliferation
- Mamillary bodies - form pea-sized swellings ventral wall of hypothalamus
Secondary Brain Vesicles - Stage 13
B1L | B2L | B3L | B4L | B5L | B6L | B7L |
Embryo Brain - Stage 22
A1L | A2L | A3L | A4L | A5L | A6L | A7L |
B1L | B2L | B3L | B4L | B5L | B6L | B7L |
Early Fetal Brain - Week 10
Adult Hypothalamus Hormones
Secreted hormone | Abbreviation | Produced by | Effect |
---|---|---|---|
Thyrotropin-releasing hormone (Prolactin-releasing hormone) |
TRH, TRF, or PRH | Parvocellular neurosecretory neurons | thyroid-stimulating hormone (TSH) release from anterior pituitary (primarily) Stimulate prolactin release from anterior pituitary |
Dopamine (Prolactin-inhibiting hormone) |
DA or PIH | Dopamine neurons of the arcuate nucleus | Inhibit prolactin release from anterior pituitary |
Growth hormone-releasing hormone | GHRH | Neuroendocrine neurons of the Arcuate nucleus | Growth hormone (GH) release from anterior pituitary |
Somatostatin (growth hormone-inhibiting hormone) |
SS, GHIH, or SRIF | Neuroendocrine cells of the Periventricular nucleus | Growth hormone (GH) release from anterior pituitary Inhibit Thyroid-stimulating hormone|thyroid-stimulating hormone (TSH) release from anterior pituitary |
Gonadotropin-releasing hormone | GnRH or LHRH | Neuroendocrine cells of the Preoptic area | follicle-stimulating hormone (FSH) release from anterior pituitary Stimulate Luteinizing hormone|luteinizing hormone (LH) release from anterior pituitary |
Corticotropin-releasing hormone | CRH or CRF | Parvocellular neurosecretory neurons | adrenocorticotropic hormone (ACTH) release from anterior pituitary |
Oxytocin | Magnocellular neurosecretory cells | Lactation (letdown reflex) | |
Vasopressin (antidiuretic hormone) |
ADH or AVP | Magnocellular neurosecretory neurons | Increases water permeability in the distal convoluted tubule and collecting duct of nephrons, thus promoting water reabsorption and increasing blood volume |
Hormones - Thyrotrophin releasing hormone (TRH), Corticotrophin releasing hormone (CRH), Arginine vasopressin (AVP), Gonadotrophin releasing hormone (GnRH), Growth hormone releasing hormone (GHRH), Somatostatin, Prolactin relasing factor (PRF), Dopamine
Growth hormone (GH) secretion from the pituitary is controlled in many different ways, including positive/negative regulation of synthesis and release by the hypothalamus. Hypothalamic GH releasing hormone (GHRH) activates and somatostatin suppresses growth hormone synthesis and release.
Hypothalamic Nuclei
Supraoptic Nucleus
(SON) Arginine vasopressin (AVP) and oxytocin (OT) synthesis and released in the posterior pituitary. These 2 hormones differ only in 2 amino acids in positions 3 and 8.
- Arginine vasopressin (AVP) peptide hormone (9aa, nonapeptide)
- synthesized as inactive preprohormone
- regulates blood volume and pressure acting on the kidney and heart
- Increased osmolality, due to blood volume reduction, increases AVP secretion.
- Oxytocin (OT) peptide hormone (9aa, nonapeptide)
- mainly produced in hypothalamic magnocellular neurons
- regulates female reproductive pregnancy-associated changes
- acts on one type of OT receptor (OTR)
- hormone is a non-glycosylated protein undergoes an initial cleavage by the convertase magnolysin (EC 3.4.24.62) to OT-Gly-Lys-Arg (OT-GKR).
- additional processing produces other OT extended molecules: OT-Gly-Lys (OT-GK) and OT-Gly (OT-G, OT-X).
- OT-G is converted by an α-amidating enzyme to C-amidated nonapeptide which is released into the circulation
- may have a role in fetal heart growth
Abnormalities: diabetes insipidus (vasopressin deficiency), syndrome of inappropriate antidiuresis (vasopressin excess)
- Links: Search Bookshelf
Paraventricular Nucleus
(PVN) Arginine vasopressin (AVP) and oxytocin synthesis and released in the posterior pituitary. These 2 hormones differ only in 2 amino acids in positions 3 and 8.
- Oxytocin peptide hormone
- mainly produced in hypothalamic magnocellular neurons
- Links: Search Bookshelf
Sexually Dimorphic Nucleus
(SDN, intermediate nucleus, INAH-1)
The SDN is twice as large in young male adults as in young females. At birth 20% of the adult SDN cell number is present, from then until 2-4 years of age cell numbers increase equally rapidly in both sexes. After this age cell numbers start to decrease in girls, creating the sex difference.
The SCN is the clock of the brain and shows circadian and seasonal fluctuations in vasopressin-expressing cell numbers. (SDN and SCN text modified from: Swaab, 1995)
- Links: Search Bookshelf
Suprachiasmatic Nucleus
(SCN) This nucleus is the clock of the brain and shows circadian and seasonal fluctuations in vasopressin-expressing cell numbers.
Tuberal Lateral Nucleus
(NTL) This nucleus is involved in feeding behavior and energy metabolism.
References
- ↑ <pubmed>20805495</pubmed>
Reviews
<pubmed>12127306</pubmed>
Articles
<pubmed>20637232</pubmed> <pubmed>20628204</pubmed> <pubmed>15840737</pubmed>
Search PubMed
Search Pubmed: hypothalamus development
Additional Images
Adult Histology
Terms
Glossary Links
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Cite this page: Hill, M.A. (2024, June 14) Embryology Endocrine - Hypothalamus Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Endocrine_-_Hypothalamus_Development
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G