STUDIES ON PITUITARY GONADOTROPHS IN PREPUBERTAL AND PUBERTAL FEMALE RATS: EFFECT OF CASTRATION AND LHRH TREATMENT

Abstract

The present studies were undertaken to elucidate ultrastructural changes in normal, ovariectomized, luteiniz ing hormone releasing hormone (LHRH) treated and ovariectomized- LHRH treated, prepubertal and pubertal female rats. Ultrastructural changes in pituitary gonadotrophs producing follicle stimulating hormone (FSH) and luteinizing hormone (LH) were carried out using the standard procedures. In some cases parallel studies were also carried out ,,,,i th light microscopy using Gomori's aldehyde fuchsin and periodic acid schiff procedures. In each physiological state, the parameters · studied included: (a) cell size, (b) granule size, (c) granule population, (d) mitochondria, (e) Golgi complex, ( f ) the nuclear size and shape, (g) endoplasmic reticulum, and (h) vesiculation of the cytoplasm . In Prepubertal animals gonadotrophs of 5,10,20 and 30 days of age showed progressive changes towards maturity past day 30 which was found to be the most critical period in transformation from immature to mature stage. Conspicuous changes were observed in granules population (day 5,112±10; day 30, 370 ± 20) and granules size (day 5, 1508±110 AO; day 30, 1810±113 AO). The cell size during this period increased from 9.5±0.2 lim to 13.3±0.45 lim. The cell shape, the mitochondria and the nuclear size and shape remained unchanged. Endoplasmic reticulum was p r ominent at all stages of development . However the Golgi complex became increasingly prominent by days 20 and 30 . The appearance of major 3 changes by day 30 indicated the preparation of gonadotrophs for entering into maturity stage. No prominent changes were observed in thyrotrophs during the same period. Changes in ovariectomized prepubertal rats (day 30) were not as dramatic as in day 60, mature cycling rats. Although vesiculation of cytoplasm was apparent in 30 day old animals, yet the change was neiWas putative as in ovariectomized mature animals tior were signs of 'c" astrate , cellI ' formation or intiation of indentation of the nuclear membrane observed. However, in animals of comparable age (30 days old) LHRH treatment (1 #g/day, for 5 days } _oF intact animals resulted in transformation of majority of gonadotrophs into .castrate cells with high vesiculation of II the cytoplasm . This condition has been termed pseudocastra- II tion. , since the gonadotrophs mimic the same transformation as in adult ovariectomized female cycling rat. The implications of pseudocastration have been discussed in parallel (,( with the effects of castration. The phenomenon of pseudo- II castration induced by LHRH alone is the first of its kind described in the present studies. Changes in 60 day' old animals castrated for 30 days reported in this thesis were similar to those documented earlier. The appearance of castrate cells with vesiculated cytoplasm and indentation of nuclear membrane wa-~ ( clearly I( observed. However, as reported by others, typical 'signet ring". cells were not seen . Unlike 30 day old LHRH-tr eated 4 animals the 60 day, old intact animals given similar LHRH treatment did not respond to LHRH challenge in the same manner as 30 day. old animals; the extent of change in gonadotrophs was far less dramatic as seen in _"p seudo- JI castrated animals (30 day. old, ovaries intact, LHRH treatment l.ug/day for 5 days) . Interestingly enough, however, 60 old ovariectomized female rats injected with LHRH did ( not show as much change, in gonadotrophs as 60 day ovariectomized animals which did not receive LHRH. This has been attributed to inhibitory effect of LHRH at this physiological state. It has been maintained in the thesis that on ultrastructural basis it is difficult to differentiate between gonadotrophs producing luteinizing hormone (LHG) and follicle stimulating hormone (FSHG) only on the basis of granules, though opinion of other workers describing separate FSH and LH granules has also been discussed .