HypothalamusBLOCK 3 – 2011-12
Robert R. Terreberry, PhD
Room 142 Ph 864.327.9827
rterreberry@carolinas.vcom.edu
Hypothalamic Zones
Mid-sagittal
Hypothalamus
Scheme
Hypothalamus Levels
Supraoptic Zone
Tuberal Zone
Mamillary Zone
Hypothalamic Afferents
Hypothalamic Efferents
Hypothalamus Connections
Pituitary Gland
Herring body
Neural
Portal
Hypothalamus
Scheme
Functional Areas
SUPRAOPTIC
ZONE
TUBERAL
ZONE
MAMILLARY
ZONE
•ADH / Oxytocin
•Para. Responses
•Lower Body Temp.
•Sleep / Rhythms
•Releasing Factors
•Satiety Center
•Avoidance
Reactions / Fear
•Symp. Responses
•Raise Body Temp.
•Waking
•Sympathetic
Responses
•Feeding
Center
•Thirst Center
Anterior
Posterior
Preoptic Area
Medial
Parasympathetic Areas
SUPRAOPTIC
ZONE
TUBERAL
ZONE
MAMILLARY
ZONE
•ADH / Oxytocin
•Para. Responses
•Lower Body Temp.
•Sleep / Rhythms
•Releasing Factors
•Satiety Center
•Avoidance
Reactions / Fear
•Symp. Responses
•Raise Body Temp.
•Waking
•Sympathetic
Responses
•Feeding
Center
•Thirst Center
Anterior
Posterior
Preoptic Area
Medial
Sympathetic Areas
SUPRAOPTIC
ZONE
TUBERAL
ZONE
MAMILLARY
ZONE
•ADH / Oxytocin
•Para. Responses
•Lower Body Temp.
•Sleep / Rhythms
•Releasing Factors
•Satiety Center
•Avoidance
Reactions / Fear
•Symp. Responses
•Raise Body Temp.
•Waking
•Sympathetic
Responses
•Feeding
Center
•Thirst Center
Anterior
Posterior
Preoptic Area
Medial
Temperature Regulation
SUPRAOPTIC
ZONE
TUBERAL
ZONE
MAMILLARY
ZONE
•ADH / Oxytocin
•Para. Responses
•Lower Body Temp.
•Sleep / Rhythms
•Releasing Factors
•Satiety Center
•Avoidance
Reactions / Fear
•Symp. Responses
•Raise Body Temp.
•Waking
•Sympathetic
Responses
•Feeding
Center
•Thirst Center
Anterior
Posterior
Preoptic Area
Medial
Circadian Fluctuation in Core Body Temperature
Temperature Regulation
Body Temperature (°C)
Temperature affects Ant. Hypothalamus /Preoptic Area
Temperature Regulation
•Promote Heat Loss
•Sweating
•Vasodilation
•Behavioral ’s
•Prevent Heat Production
• muscle tone / activity
• thyroid hormone / epinephrine
• appetite (calories)
Temperature affects Post. Hypothalamus
Temperature Regulation
•Promote Heat Production
•Shivering, muscle tone
• thyroid hormone / epinephrine
•Prevent Heat Loss
•Vasoconstriction
•Behavioral ’s
Lesion of Anterior Hypothalamus
Temperature Regulation
•Inability to lower body temperature
•Hyperthermia in a hot environment
•41˚C (106˚F) – convulsions
•43˚C (109˚F) – death
•Inability to increase body temperature
•Hypothermia in a cold environment
•Confusion followed by loss of thermoregulation at28˚C (82˚F)
Lesion of Posterior Hypothalamus
•Interleukin-1 is endogenous pyrogen
•Released from macrophages
•Acts on neurons and glia in medial preoptic area –“pyrogenic zone”
•Glial cells produce cytokines and PGE2
•PGE2 cold-sensitive neurons
•PGE2 warm-sensitive neurons
•PGE2 will increase temperature set-point andthus body temperature will rise - fever
Fever
Febrile Conditions
Body Temperature (°F)
Feeding Regulation
SUPRAOPTIC
ZONE
TUBERAL
ZONE
MAMILLARY
ZONE
•ADH / Oxytocin
•Para. Responses
•Lower Body Temp.
•Sleep / Rhythms
•Releasing Factors
•Satiety Center
•Avoidance
Reactions / Fear
•Symp. Responses
•Raise Body Temp.
•Waking
•Sympathetic
Responses
•Feeding
Center
•Thirst Center
Anterior
Posterior
Preoptic Area
Medial
Feeding Regulation
Feeding Center
•Lateral hypothalamic nucleus
•Stimulated by low glucose levels
•Initiates feeding
•Amphetamines inhibit food intake by enhancing Norepi and DAlevels in lateral hypothalamic nucleus
•Ventromedial nucleus
•Stimulated by high glucose levels or CCK
•Inhibits food intake
Satiety Center
Feeding Regulation
Leptin
•Protein hormone released by fat cells
•Circulating levels directly proportional to amount ofadipose tissue in body
•Acts on receptors in lateral hypothalamus
•Inhibits affects of neuropeptide Y andanandamine – both feeding stimulants
•Inhibits feeding
•Genetically altered mice with no leptin or leptinreceptors are obese
Feeding Regulation
Ghrelin
•Hormone that stimulates appetite
•Produced in stomach and upper small intestine inresponse to significant weight loss
•May explain why it is difficult to maintain weightloss after dieting
•Not produced in patients that have undergone gastricbypass surgery
Lesion of feeding center
Feeding Regulation - Lesions
•Results in loss of desire to eat
•Leads to aphagia and ultimately death
•Results in compulsive overeating
•Leads to hyperphagia and obesity
Lesion of satiety center
Water (Fluid) Regulation
SUPRAOPTIC
ZONE
TUBERAL
ZONE
MAMILLARY
ZONE
•ADH / Oxytocin
•Para. Responses
•Lower Body Temp.
•Sleep / Rhythms
•Releasing Factors
•Satiety Center
•Avoidance
Reactions / Fear
•Symp. Responses
•Raise Body Temp.
•Waking
•Sympathetic
Responses
•Feeding
Center
•Thirst Center
Anterior
Posterior
Preoptic Area
Medial
Fluid Regulation
Thirst Center
•In anterior and lateral hypothalamus
•Closely tied to supraoptic/ADH systemcontrolling fluid homeostasis
•Stimulation results in fluid consumption -polydipsia
•Ventromedial nucleus
•Tied to food intake
•Food and fluid intake not mutually exclusive
Satiety Center
Lesion of lateral hypothalamus
Fluid Regulation - Lesions
•Loss of thirst center
•Results in very little fluid intake - adipsia
•Results in compulsive overeating/drinking
•Leads to hyperphagia and polydipsia
Lesion of satiety center
Sexual Behaviors
SUPRAOPTIC
ZONE
TUBERAL
ZONE
MAMILLARY
ZONE
•ADH / Oxytocin
•Para. Responses
•Lower Body Temp.
•Sleep / Rhythms
•Releasing Factors
•Satiety Center
•Avoidance
Reactions / Fear
•Symp. Responses
•Raise Body Temp.
•Waking
•Sympathetic
Responses
•Feeding
Center
•Thirst Center
Anterior
Posterior
Preoptic Area
Medial
Sexual Behaviors
•Preoptic area regulates release ofgonadotrophic hormones
•Cyclical in females
•Topical with fluctuations in males
•Preoptic area important in male behaviors -mounting
•Ventromedial nucleus important in femalebehaviors - lordosis
Preoptic area is different in malesand females
•Sexually dimorphic nucleus
•Larger in male rats vs female rats
Sexual Orientation
Human studies
•Simon LeVay
•INAH-3 smaller in homosexual males, size ofheterosexual females
Sexual Orientation
Human studies
•Laura Allen and Roger Gorski
•Area of anterior commissure is normally larger in womenthan men
•Anterior commissure 34% larger in homosexual malesthan in heterosexual males; 18% larger than those inheterosexual females
•Dick Swaab
•Suprachiasmatic nucleus larger (twice the number ofcells) in homosexual males than in heterosexual males
Sexual Orientation
Human studies
•Savic et al.
•PET scans of heterosexual subjects smellingputative human pheromones
•AND (in male sweat), EST (in pregnant femaleurine)
•HeW (AND) = preoptic area and DM hypo.
•HeM (EST) = PVN and DM hypothalamus
•HeW (EST) and HeM (AND) = areas thatprocess common odors, no hypothalamus
Sexual Orientation
Human studies
•Savic et al.
•PET scans of homosexual male andheterosexual female subjects smellingputative human pheromones
•HoM (AND) = PVN and DM hypothalamus
•HeW (AND) = PVN and DM hypothalamus
Sexual Orientation
Human studies
•Lindstrom and Savic
•PET scans of lesbian subjects smelling putativehuman pheromones
•HoW (AND) = olfactory networks, not hypo.
•HoW (EST) = partly shared responses withHeM - anterior hypothalamus
Sexual Orientation
Sexual Orientation
Fear and Pleasure
SUPRAOPTIC
ZONE
TUBERAL
ZONE
MAMILLARY
ZONE
•ADH / Oxytocin
•Para. Responses
•Lower Body Temp.
•Sleep / Rhythms
•Releasing Factors
•Satiety Center
•Avoidance
Reactions / Fear
•Symp. Responses
•Raise Body Temp.
•Waking
•Sympathetic
Responses
•Feeding
Center
•Thirst Center
Anterior
Posterior
Preoptic Area
Medial
Fear and Pleasure
Flight response
•Stimulation of lateral anterior hypothalamus
•Sympathetic response
Ventromedial nucleus stimulation
•Defensive response - fear
•Avoidance reaction
Preoptic area stimulation
•Pleasure
Circadian Rhythms
SUPRAOPTIC
ZONE
TUBERAL
ZONE
MAMILLARY
ZONE
•ADH / Oxytocin
•Para. Responses
•Lower Body Temp.
•Sleep / Rhythms
•Releasing Factors
•Satiety Center
•Avoidance
Reactions / Fear
•Symp. Responses
•Raise Body Temp.
•Waking
•Sympathetic
Responses
•Feeding
Center
•Thirst Center
Anterior
Posterior
Preoptic Area
Medial
Circadian Rhythms
Suprachiasmatic nucleus is considered to bethe biological clock
•Endogenous rhythm with 24 hour periodicity
•Rhythm influenced by light
•Retina projects directly to SCN
Sleep and Wakefulness
SUPRAOPTIC
ZONE
TUBERAL
ZONE
MAMILLARY
ZONE
•ADH / Oxytocin
•Para. Responses
•Lower Body Temp.
•Sleep / Rhythms
•Releasing Factors
•Satiety Center
•Avoidance
Reactions / Fear
•Symp. Responses
•Raise Body Temp.
•Waking
•Sympathetic
Responses
•Feeding
Center
•Thirst Center
Anterior
Posterior
Preoptic Area
Medial
Sleep and Wakefulness
•In anterior hypothalamus / preoptic area
•Production of PGD2 promotes sleep
•Lesions result in insomnia
•In posterior hypothalamus
•Production of PGE2 promotes waking
•Lesions result in hypersomnolence
Questions??