Endocrine - Hypothalamus Development
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 adult, large neurosecretory cells of the supraoptic nucleus (SON) and the paraventricular nucleus (PVN) project to the neurohypophysis from the hypothalamus.
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.
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.
Other key nuclei within the hypothalamus include the sexually dimorphic nucleus (SDN, intermediate nucleus, INAH-1), suprachiasmatic nucleus (SCN) and tuberal lateral nucleus (NTL).
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)
The tuberal lateral nucleus (NTL) is involved in feeding behavior and energy metabolism.
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
| Lecture - Early Neural Development | Lecture - Late Neural Development | Lecture - Head Development | original page
Development Overview
- Neuroectoderm - prosenecephalon then diencephalon
- ventro-lateral wall intermediate zone proliferation
- Mamillary bodies - form pea-sized swellings ventral wall of hypothalamus
Adult Endocrine 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 |
Supraoptic Nucleus
(SON)
Paraventricular Nucleus
(PVN)
Sexually Dimorphic Nucleus
(SDN, intermediate nucleus, INAH-1)
Suprachiasmatic Nucleus
(SCN) This nucleus is the clock of the brain and shows circadian and seasonal fluctuations in vasopressin-expressing cell numbers.
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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