1977 Volume 24 Issue 1 Pages 19-39
Chronic subcutaneous injections with synthetic TRH (10μg/0.2ml of gelatine-saline) for 21 days slightly raised not only serum TSH but also serum LH concentration; those for 7 days tended to diminish the serum LH and FSH concentration. The magnitude of rise in the serum TSH was approximately equivalent to 1/5 of the value 30 days after a single injection with the same dose of TRH. The injections of synthetic LRH (5μg/0.2ml) for 21 days, on the other hand, raised the serum LH concentration 3.5 times as high as a single injection did. Pituitary TSH concentration was lowered conspicuously after TRH injections for 21 days; pituitary LH concentration was diminished remarkably after LRH injections for 21 days. Serum FSH concentration was not changed by the same LRH injection, while pituitary FSH concentration was diminished. Injections of TRH and LRH in combination for 7 or 21 days lowered the pituitary LH and FSH content more extensively than the separate LRH injection for 7 or 21 days. Some of our assay data may suggest the possible: synergistic or countervailing influences of the releasing hormones upon the secretion of the other trophic hormones. This is contradictory to the concept “one releasing hormone is responsible for one target cell”. This discrepancy may be explained by our working hypothesis as to the secretory cycle of the basophil.
It was tentatively concluded from our morphological manifestation that each releasing hormone did not act limitedly upon one target cell but universally upon a series of basophils. Both TRH and LRH exerted the analogous morphokinetic functions to convert the II-type cell (classical thyrotroph) into the III-type cells (classical LH-gonadotrophs) which are destined to turn into the III/IV-and IV-type cells (classical FSH-gonadotrophs), and to revert them to the original TI-type cells in the course of secretory cycle. There was a morphological evidence to show that the releasing. hormone might accelerate the rotation of secretory cycle of the basophil. Our working. hypothesis is that the various types of basophils may not be independent of each other, but modify their shape and property according to the different phases of secretory cycle, i. e., synthesizing, storing, secreting and resting phases. The II/III-and III-type cells were particularly accumulated after a long-term TRH injection; the IV/II-or II-type cells were accumulated but the IV-type cells were diminished in number after a separate LRH injection or the TRH and LRH injections in combination. The accumulation of the resting cells (IV/II-type) may account for the temporal stabilization of secretory cycle by the chronic injection.
