NEU 257
3/3/2011

• “between brain”
• Posterior part of embryonic forebrain
• Lies between brainstem and cerebral hemispheres
• Includes: thalamus, hypothalamus, subthalamus, epithalamus

• Below rostral thalamus (hypo =“under”/”beneath)
• Vital regulatory functions include: temperature, heart rate, blood pressure, blood osmolarity, goal seeking behavior, emotional behavior, visceral nervous system, sexual activity, food & water intake, aggression
• Forms floor and lower walls of third ventricle
• Contains various classes of peptidergic neuroendocrine cells which control endocrine function
• Communicates with cortex via limbic system and also via direct projections

• Endocrine system (HPA: hypothalamopituitary-adrenal axis)
• Autonomic nervous system
• Motivation system
….Also adaptive emotional behavior

Gross anatomy of the Hypothalamus science.tjc.edu/ images/brain/Index.htm

• receives info on external and internal conditions:
– specific sensory info (e.g., direct retinal projection)
- input from visceral senses (NTS: nucleus of the solitary tract: taste )
– contains many neurons that are sensitive to local temperature, osmolarity, glucose, sodium
– circulating hormones influence it via the circumventricular organs

Retinohypothalamic tract
III
SCN SCN

•Brain regions near ventricles that lack a blood-brain barrier, e.g., subfornical organ, OVLT, median eminence, area postrema
•Highly vascularized
•Influenced by circulating hormones, osmotic changes, substances in CSF, afferent fibers from other parts of the nervous system

• “Large” neurons
• Located in paraventricular and supraoptic nuclei
• Secrete oxytocin and vasopressin into general circulation via posterior pituitary
• Oxytocin uterine contraction & milk secretion
• Vasopressin vasoconstriction, water resorption by the kidney

Brainmaps.org

Magnocellular Secretory System clem.mscd.edu/~raoa/ bio2320/endo1/sld003.htm

• “small” neurons
• Located in medial basal region, arcuate and tuberal nuclei, periventricular region, preoptic and paraventricular nuclei
• Secrete releasing and inhibiting hormones into portal vasculature via anterior pituitary
• Nobel prize awarded to Guillemin (Salk),
Schally and Yalow in 1977 for their
(independent) work in proving the hypothesis that the hypothalamus releases hormones that regulate the pituitary

Brainmaps.org

Hypothalamic Portal System clem.mscd.edu/~raoa/ bio2320/endo1/sld003.htm

Hypothalamic hormone
Prolactin release-inhibiting hormone
(PIH), dopamine
Growth hormone release-inhibiting hormone (GIH; somatostatin)
Melanocyte-stimulating hormone release inhibiting factor (MIF)
Anterior pituitary hormone
Prolactin
GH, thyrotropin
MSH

Hypothalamic hormone
Thyrotropin-releasing hormone
(TRH)
Corticotropin-releasing hormone
(CRH) gonadotropin-releasing hormone
(GnRH)
Growth-hormone releasing hormone (GHRH)
Prolactin-releasing factor (PRF)
Melanocyte-stimulating hormonereleasing factor (MRF)
Anterior pituitary hormone
Thyrotropin, prolactin
Adrenocorticotropin,
LH, FSH
GH
Prolactin
MSH, b
-endorphin b
-lipotropin

Peripheral Influence of Hypothalamus clem.mscd.edu/~raoa/ bio2320/endo1/sld003.htm

•Also known as “orexin”
•Peptide involved in arousal and feeding behavior
•Project to thalamus, cortex and brainstem regions associated with arousal, cardiovascular control, and autonomic functions
•Few thousand neurons
•Loss of hypocretin neurons implicated in human narcolepsy
From Thannickal et al., Neuron 27: 469, 2000