HISTOCHEMICAL INVESTIGATION OF THE EFFECTS OF OESTROGEN, PROGESTERONE AND RELAXIN ON GLYCOGEN, AMYLOPHOSPHORYLASE, TRANSGLYCOSYLASE AND URIDINE DIPHOSPHATE GLUCOSE-GLYCOGEN TRANSFERASE IN UTERI OF MICE

SUMMARY (1) The effects of combinations of oestrogen, progesterone and relaxin on glycogen content, and on amylophosphorylase, transglycosylase and uridine diphosphate glucose-glycogen glucosyl transferase activities in the corpus uteri of intact and ovariectomized virgin mice were investigated by histochemical techniques. (2) Glycogen and the enzyme activities were localized to myometrial and arterial muscle fibres, mobilized leucocytes when present, and luminal and glandular epithelium. Transglycosylase activity was not found in glandular epithelium and no information was obtained about UDPG-glycogen synthesis in epithelium or in leucocytes; otherwise the distribution of the three activities appeared to be similar. (3) In untreated ovariectomized mice no glycogen was detected in vivo and phosphorylase activity was low. In untreated intact mice little histochemically detectable glycogen was found in myometrial muscle at any stage of the cycle and almost no UDPG-synthesized glycogen; amylophosphorylase activity appeared to be increased during pro-oestrus and oestrus. (4) Oestrogen produced increased amounts of glycogen in vivo and stimulated phosphorylase activity in both muscle layers in intact and ovariectomized mice; UDPG-glycogen synthesis was probably also increased. (5) Relaxin had no detectable effect on myometrial glycogen or on phosphorylase activity in non-primed ovariectomized mice, but both were increased when relaxin was given to oestrogen-primed ovariectomized mice or to intact mice at pro-oestrus or oestrus. Only small increases were detected in UDPG-glycogen synthesis. (6) In both intact and ovariectomized oestrogen-primed mice progesterone had a differential action on the two layers of the myometrium: it increased both glycogenolysis and phosphorylase activity in the longitudinal fibres, but inhibited phosphorylase activity in the circular fibres without resulting in glycogen synthesis in vivo. Results on UDPG-glycogen synthesis were inconclusive. Simultaneous administration of relaxin prevented the inhibitory action of progesterone on glycogen and phosphorylase activity in the circular muscle layer and UDPG-glycogen synthesis was also high in these mice. (7) No consistent effects of the hormones were detected on glycogen or enzyme activities in arterial muscle. (8) The histochemical tests visualized total phosphorylase activity but gave no information about hormonal influence on phosphorylase a and b ratios.