Hypothalamus Flashcards
inputs to hypothalamus
- sensory input from entire body
- visceral inputs (pain)
- internal sensor neurons that respond to change in sensory input vs biological set point
- physiological and cognitive aspects of emotion
output from the hypothalamus
- forebrain
- limbic structures
- cortex
- brainstem (auto NS)
- pitutary
what is used to activate hypothalamus?
steroid and peptide hormones
what is continuous with hypothalamus anteriorly
preoptic area
tuber cinereum
grey swelling on ventral surface of brain between optic chiasm and mammillary body
–raised area= median eminence
median eminence
- -forms infundibular stem of pituitary gland
- -contains hypophysial portal system
forebrain afferents
- septal nuclei/forebrain
- hippocampus
- amygdala
- orbital/frontal cortex
- retina
- brainstem/spinal cord
Limbic bidirectional afferents
median forebrain bundle
fornix
stria terminalis
brainstem/spinal cord bidirectional afferents
- median forebrain bundle
- dorsal longitudinal fasciculus
retina bidirectional afferents
retinohypothalamic tract
hypothalamus efferents
- mammilothalamic
- median forebrain bundle
- mammilotegmental (reticular)
- median forebrain bundle (autonomic)
- dorsal longitudinal fasciculus (autonomic)
- supraoptichypophyseal (endocrne)
median forebrain bundle
somatic and metabolic activity associated with stress, aggression, and rage
supraoptichypophyseal tract
hypothalamus –>posterior pituitary (neurohypo)
via arginine and AVP
AVP
acts on kidney to promote H20 reabsorption
lesions would make Diabetes Insipidus (abnormal production of very large quantities of very dilute urine)
oxytocin
- sexual stimulation, uterine dilation, nursing, stress
- uterine myometrial contraction during partition and contraction of myoepithelial cells in mammillary alveoli–>promote milk secretion
- trust, empathy, eye contact, generosity
tuberoinfundibular tract
hypothalamus parvocellular neurons –> adenohypo (anterior pit)
via hypophyseal portal system
two ways steroid hormones act
activational
organizational
activational
essential for control of reporduction (neuronal function) and non-reproductive behavior (premenst. symptoms, PMDD, post partum depression, enhanced seizure susceptibility)
- normal cycling females
- sex specific behavior males & females
organizational
early in neonatal dev and later in adolescence to impart perm. changes in neural structures that underly many sexually differentiated aspects of brain and behavior
- -VMN
- -regoin of Preoptic area
*critical period (second critical period?)
GnRH
gonadotrophin releasing hormone
hypothal-pituitary-gonadal pathway
Hypothal–GnRH–>Ant Pituitary –FSH/LH–>Gonads (sex hormones)
neg regulation at ant pit and hypothal
post reg at ant pit tooo
kisspeptin
Ant Pit/Hypothal do NOT express high levels of R for sex steroids, but have kisspeptin
presyn cells synthesize this neuron and it provides presyn inputs to GnRH cells
disorders of HPG
- catamenial epilepsy
- changes in menstraul cycle
- premenstraul dysphoric disorder
- postpartum depression
cycling proteins
CLOCK
bmal1
cry
per
cycling proteins are regulated by
specific kinases
mutations in casein kinase and per genes
implicated in familial advanced sleep phase syndrome (FASPS)
light
alters specific phase of cycle, but does nto change that it operates on a 24 hour period
master circadian regulator
suprachiasmatic nucleus of hypothalamus
SCN sends efferents to
hypothal -PVN (paraventricular nucleus) -VMN (ventromedial nucleus) -LHA (lateral hypothalamic area) beyond hypo -regions implicated in diurnal regulation of arousal, psychomotor perf, and sensory perception
SCN and pineal gland
SCN–>dorsomedial nucleus of hypothalamus–> spinal cord and superior cervical ganglion–>pineal gland
pineal gland
secretes melatonin
regulates sleep/wake cycles
hypothalamus and food/energy
balances food intake with energy expenditure
-VMN, Ac, LHA
orexigenic
stimulates appetite/feeding
anorexigenic
suppresses appetite/feeding
insulin secreted
by pancreatic b cells
ghrelin
initiates food intake
decreases energy utilization
increases adiposity
CCK
acute info about GI fill via vagal afferent info to nucleus of solitary tract (autonomic control region in medulla)–>limits meal size
Leptin
secreted by white adipose tissue–>produces peripheral signal from body to brain reflecting state of nutrition/energy reserves
leptin is special because
it has access to hypothalamic nuclei through BBB because of its location, active transport, and through hypothal. neurons that send projections directly into blood stream
leptin is regulated via
Ob gene
leptin’s role is to
spur body to maintain adequate fat stores in absence of nutritional deficit NOT to diminish energy intake under conditions of adequate or more than adequate fat reserves
leptin R/mediate leptin effects
1) arcuate–>make AgRP
2) arcuate–>make NYP
3) VMN–>express SF1
4) lateral hypothalamus–>express neurotensin
cytokines alter
leptin signals in NS via Jak/stat pathway–>alters gene expression in neurons that express long form of R
AgRP & NYP
orexigenic
decrease in leptin (double punch)
- stimulate NYP/AgRP neurons–>blocks binding of a-MSH to melanocortin R on neurons in PVN–>stimulation of neurons in PVN that increase food intake and decrease anorexic pathways
- decrease POMC neurons which normally release a-msh
==> knocks out anorexigenic pathways
orexin
decreases via leptin
increases via ghrelin
–small group neurons in LHA that regulate weight and food intake by establishing internal set point
brown fat
negligible amounts in adults
utilizes calories to generate heat
activated via brown fat
Narcolepsy
premature entry into REM sleep, cataplexy (rapid muscle weakness, but no loss of consciousness)
–90% loss of orexin neurons
rexin has a central role in
behaviors that regulate arousal (wakefulness, other consum behaviors [eating, drug seeking, sex]
Modafinil (provigil)
psychostimul drug–>promotes orexin signaling
- can also change DA in mesolimbic pathway by alter interfering with DA
- ->inc in NAc (results in change in some feelings to positive ones)
