Brain Research, 93 (1975) 363-366 © Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
363
Localization of vasopressin in discrete areas of the rat hypothalamus
JACK M. GEORGE AND DAVID M. JACOBOWITZ Department of Medicine, Ohio State University, Columbus, Ohio 43210 and National Institutes of Mental Health, Laboratory of Clinical Science, Bethesda, Md. 20014 (U.S.A.)
(Accepted April 29th, 1975)
Bargmann and Scharer in 19512 proposed a concept of neurosecretion of hormones by nervous tissue having characteristics of both glandular tissue and neurons. They based this concept on the findings of specifically stainable colloid in neuronal cell bodies of supraoptic and paraventricular nuclei of the cat hypothalamus, in nerve terminals in the posterior pituitary, and in axons connecting these structures. The posterior pituitary is the known site of storage and secretion of the antidiuretic hormone, arginine vasopressin, and of the uterine contraction hormone, oxytocin. The implication of this concept of neurosecretion, which has been widely accepted, is that these hormones are synthesized in neuronal cell bodies in the supraoptic and paraventricular nuclei of the hypothalamus, packaged into granules, and transported along axons to the posterior pituitary for storage and subsequent release in response to physiologic stimuli. However, because of the complex anatomy of the hypothalamus the precise localization and quantitation of the hormones within the hypothalamus has not been possible. The recent development of a technique for microdissection of individual hypothalamic nuclei v coupled with a sensitive and specific radioimmunoassay for arginine vasopressin 3 permits the quantitation of this hormone in a variety of hypothalamic nuclei and other areas. Male Sprague-Dawley rats weighing 250-300 g were killed by decapitation and their brains removed and frozen in dry ice. Serial 300/zm frozen sections were cut in the frontal plane in a cryostat at --10 °C. Samples of hypothalamic nuclei and other areas were removed from the frozen sections with stainless steel cannulas 300, 500, or 1000/~m in diameter. For each rat brain 2-4 pellets of tissue were removed from each nuclear area and pooled. The pooled tissue samples from each nuclear area were homogenized in 0.1 ml of 0.1 N HCI by ultrasound. An aliquot was taken for protein determination by the micromethod of Lowry et aI. 6 and the remainder assayed for arginine vasopressin as previously described 3. The results of these assays are shown in Table I with the microdissected areas designated by the nomenclature of K6nig and Klippel 5. All brain areas were assayed in tissue from 4 rats. The highest concentration ofvasopressin was found in the median eminence samples with appreciable amounts in the supraoptic nucleus and the retrochiasmatic area which contains accessory supraoptic cell bodies and axons from the
364 TABLE 1 ARGININE VASOPRESSIN C O N T E N r OF MICRODISSECTEI) BRAIN AREAS
pg A VP/t~Kprotein Dleall ~
Median eminence Retrochiasmatic area N. supraopticus N. paraventricularis N. suprachiasmaticus N. arcuatus N. preopticus periventricularis N. dorsomedialis N. interstitialis striae terminalis N. septalis fimbrialis N. preopticus medialis N. preopticus, pars suprachiasmatica N. preopticus lateralis Globus pallidus Organon subfornicale N. hypothalamicus anterior N. anterior ventralis thalami N. ventralis thalami N. ventromedialis Habenulae Dorsal bundle Hippocampus Organon subcommisurale Superior colliculus Medial geniculate body N. interpeduncularis Substantia nigra, zona compacta Substantia nigra, zona reticulata Organ vasculosum Commissura posterior Olfactory tubercle Pyriform cortex
441 72 40 24 23 4
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