ISSN:
1432-0878
Keywords:
Hypothalamic-hypophyseal neurosecretory tracts (rat)
;
Incorporation of 35S-cysteine
;
Kinetics of neurosecretory material
;
Autoradiography
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary The fate of 35S-cysteine incorporated into the hypothalamic-hypophyseal neurosecretory system was followed in normal rats as a function of time from 30 min up to 30 hrs after intraperitoneal administration (11 different times, three rats each). Autoradiography and grain counting were employed to determine quantitatively the activities present in: supraoptic nucleus (SON), paraventricular nucleus (PVN), three different sites in the hypothalamic-hypophyseal tract (HHT), corresponding to its initial, middle and late portions, and neurohypophysis (NH). In SON and PVN, the kinetic behaviour of 35S-cysteine was compatible with a two-compartment model, implying decline of tracer activity in accordance with two exponential components. Of these, the slow throughput component had its closely equivalent, apparently independent, counterparts in the HHT and NH. Replicas of the rapidly abating activity peak were seen, superimposed on the slow component, in the HHT with such timing of its appearance at the various sites, as to be consistent with the concept of travel through the HHT, at substantially constant speed and without delay, of material rich in 35S-cysteine that has been primarily synthesized in the SON and PVN (with the “transport theory of neurosecretion”). This flow was calculated to have a velocity in the order of 0.6 mm per hour. The kinetic phenomena and their association with the supposed sites of synthesis, and transport, of the neurosecretory material are discussed with reference to earlier literature.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00355035
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