Neurons without dendrites? – A novel type of neurosecretory cell in locusts

Injection of an homogenate of identified neuron R15 into the hemocele of Aplysia produced a weight increase of 3-10% within 90 min. Control injections of several other identified neurons or of seawater, were ineffective. The weight increase occurred even when the animals were maintained in 5% hyperosmotic seawater. The activity of the R15 homogenate was retained after acidification to pH 2 and heating to 100 degrees C; but activity was destroyed by proteolytic digestion with Pronase. Dialysis in cellulose dialysis tubing resulted in a significant loss of aion on Sephadex G-50 (nominal exclusion limits 1,500-30,000 daltons), activity was present in the partially included volumes, but was absent in the totally excluded or totally included volumes. The data support the notion that R15 contains one or more hormones involved in ionic regulation or water balance. The results of bioassays of R15 extracts subjected to different treatments are consistent with the hypothesis that activity is due to one or more stable polypeptides of relatively low molecular weight.

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An Autoradiographic Study of Neurosecretory Cell Activity of Allatectomized Females of the Grasshopper, Melanoplus sanguinipes (Fab.)

Zeitschrift für Naturforschung C ◽

10.1515/znc-1975-7-815 ◽

1975 ◽

Vol 30 (7-8) ◽

pp. 511-515

Author(s):

G. S. Dogra

Keyword(s):

Neurosecretory Cell ◽

Cell Activity ◽

Secretory Activity ◽

Autoradiographic Study ◽

Neurosecretory Cells ◽

Corpus Allatum ◽

High Uptake ◽

Melanoplus Sanguinipes ◽

Gradual Accumulation ◽

Activity Cycles

Abstract Neurosecretory cell activity was studied autoradiographically in the allatectomized females of Melanoplus sanguinipes on every alternate day and in the normal control females on every fourth day for a period of 34 days. Experimental females exhibited five activity cycles against the two recorded by the control females. There was a comparatively high uptake of [3H] cystine by the neurosecretory cells of the experimental females on a particular day. During the first 12 days there was no accumulation of stainable colloid in their system. By the 24th day there was a slow and gradual accumulation of the colloids in the cells and their tracts so that on 34th day the system was well loaded with these colloids. In control females there was good accumulation of the stainable material during the first 12 days and then it declined so that 20 day old females had very little material in their system. This was followed by a massive accumulation of the stained colloids by 32nd day. The uptake of [3H] uridine was very high in the nerve-regenerate of the experimental females, and there were six cycles of secretory activity during the period of experimentation. The corpus allatum of control females, like their neurosecretory cells, exhibited only two activity cycles. Since the activity of the neurosecretory cells parallels the RNA synthesis in the nerve-regenerate, it is postulated that the neurosecretory cells produce factors for nerve-regeneration. On the basis of high uptake of isotopes by the neurosecretory cells of those allatectomized females in which the oocytes were mature it is suggested that the hormone (s) produced by the neurosecretory cells are perhaps responsible for oocyte maturation in these allatectomized females.

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