Download Anterior nuclei

Cell Bio 12- Hypothalamus
Hypothalamus serves as an integrator of somatic, visceral, endocrine, and immune functions
 The hypothalamus exerts CNS and systemic influences by two mechanisms:
1. Neural (local circuits, afferent and efferent projections)
2. Neurohumoral (i.e., hormonal, vascular, neuroendocrine functions, neuroimmune influences)
Cell Bio 12- Hypothalamus
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Afferent Connections to the Hypothalamus
The fornix conveys afferent fibers from the hippocampus, it is an importat fiber tract of the limbic system
The medial forebrain bundle transmits afferent fibers from the olfactory areas to the preoptic nuclei
The stria terminalis conveys afferent fibers from the amygdala
The peduncle of the mamillary bodies transmits visceral afferent fibers
Efferent Connections from the hypothalamus
The dorsal longitudinal fasciculus reaches to parasympathetic nuclei (3,7,9, 10)
The mamillotegmental tract distributes efferent fibers to the tegmentum of the midbrain; these are then
relayed to the reticular formation. The fibers of this tract mediate the exchange of autonomic information
between the hypothalamus, cranial nerve nuclei, and spinal cord
The mamillothalamic fasciculus connects to cingulate gyrus
Hypothalamic - hypophyseal tract communicates with pituitary gland
Cell Bio 12- Hypothalamus
Pituitary Vasculature and Hypothalamic Hormone Delivery (Neurosecretion)
Portal veins branch into another series of capillaries within the anterior pituitary
Capillaries in anterior and posterior pituitary coalesce into veins that drain into systemic venous blood.
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Medial Preoptic Nucleus: Is characterized by sexual dimorphism involving hormonal influences on neuronal
maturation
Contains high density of gonadotropin-releasing hormone producing neurons which synthesize large peptides
that are directed at target cells in the anterior pituitary
Anterior preoptic region: maintains constant body temperature
Suprachiasmatic nucleus.: receives direct retinal input; circadian rhythm
Cell Bio 12- Hypothalamus
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Paraventricular and Supraoptic Nuclei:
o Neurosecretory cells whose axons project to posterior pituitary
o Paraventricular nucleus secrete oxytocin,
o Supraoptic nucleus secrete vasopressin.
Posterior Pituitary (Neurohypophysis)
Paraventricular and supraoptic nuclei contain neurons that produce oxytocin or vasopressin
Hormones travel down axon by axonal transport and are stored and released at terminals in the posterior
pituitary
Hormones released into systemic circulation upon excitation
Systemic feedback to hypothalamus via CircumVentricular Organs (OVLT and SFO)
Cell Bio 12- Hypothalamus
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Dorsomedial and Ventromedial Nuclei.:
o Neurons involved in feeding, reproductive, and parenting behavior, thermoregulation
Anterior nuclei: regulate appetite and food intake. Medial part lesion causes obesity, lateral part lesion causes
anorexia
Posterior Hypothalamic Region :
Temperature regulation function has been assigned. Responds to temperature changes, such as sweating. Lesion
causes hypothermia
Also, arousal, shift of attention; especially as a function of behavioral states mediated by hypothalamus
Mammillary body: involved in limbic forebrain and midbrain functional integration
Inflammatory response-associated chemicals (cytokines) which may influence thyroid function during severe infection
(sepsis) through systemic feedback to hypothalamus
Cell Bio 12- Hypothalamus
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Lesions in certain cortical regions can be associated with severe autonomic dysfunctions
Limbic system
o Amygdala
o Cingulate gyrus
o Lateral septal nuclei
o Insular cortex, others
Cortical influences on hypothalamic output leading to altered behavioral states
o Emotion, pain
o “Drives”: hunger, thirst, sex
o Fight or flight
o Forms of anxiety
Cell Bio 12- Hypothalamus
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Cell Bio 12- Hypothalamus
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Cell Bio 12- Hypothalamus
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Hypothalamic Nuclei Involved in sleep
 Activation of VLPO neurons contributes to the onset of sleep
 lesions tends to produce insomnia
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Cell Bio 12- Hypothalamus
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