The response of creatine kinase specific activity in rat pituitary to estrogenic compounds and vitamin d less-calcemic analogs

Abstract

We examined the response of rat female pituitary at different metabolic stages to treatments with estrogenic compounds and vitamin D analogs. Immature or ovariectomized (Ovx) female rats responded by increased creatine kinase specific activity (CK) to estradiol-17beta (E(2)), genistein (G), daidzein (D), biochainin A (BA), quecertin (Qu), carboxy- G (cG), carboxy- BA (cBA), and raloxifene (Ral). The response was inhibited when Ral was injected together with the estrogens. CK was increased when hormones were injected daily into Ovx rats for 4 different time periods. Pretreatment with the less-calcemic vitamin D analogs JK 1624 F(2)-2 (JKF) or QW 1624 F(2)-2 (QW) followed by estrogenic injection resulted in increased response and sensitivity to E(2) and loss of inhibition of E(2) by Ral. CK was also increased by feeding with E(2) or licorice or its components dose- and time- dependent in immature or Ovxrats. Diabetic female rats did not respond to increased doses of E(2). In conclusion, rat female pituitary is estrogens-responsive organ, suggesting to considerits response for HRT in postmenopausal women for both beneficial and hazardous aspects.

Figure 1

Stimulation of creatine kinase (CK) specific activity by different estrogenic compounds in pituitary in immature female rats (a) and ovariectomized female rats (b). Rats were treated and assayed for CK activity as described in Section 2. Results are means ± SEM for n = 5–15 rats/group. Experimental means compared to control means: *P < .05 and **P < .01. Basal activity in pituitary from intact rats was 1.12 + 0.17 μmol/min/mg protein and in Ovx rats was 0.47 + 0.02 μmol/min/mg protein.

Figure 2

Stimulation of creatine kinase (CK) specific activity by different estrogenic compounds with and without raloxifene (Ral; cross-hatches bars) in pituitary from immature (a) and from ovariectomized female rats (Ovx; b). Rats were treated and assayed for CK activity as described in Section 2. Results are means ± SEM for n = 5–15 rats/group. Experimental means compared to control means: *P < .05 and **P < .01. Basal activity in Pi from intact rats was 1.22 + 0.27 μmol/min/mg protein and from Ovx was 0.67 + 0.22 μmol/min/mg protein.

Figure 3

Stimulation of creatine kinase (CK) specific activity by different estrogenic compounds with and without E₂ in pituitary from immature (a) and from ovariectomized female rats (Ovx; b). Rats were treated and assayed for CK activity as described in Section 2. Results are means ± SEM for n = 5–15 rats/group. Experimental means compared to control means: *P < .05 and **P < .01. Basal activity in organs from immature and OVX rats were 1.02 + 0.15 μmol/min/mg protein and 0.67 + 0.22 μmol/min/mg protein, respectively.

Figure 4

Stimulation of creatine kinase (CK) specific activity by different estrogenic compounds in pituitary from ovariectomized female rats, injected daily for 4 months. Rats were treated and assayed for CK activity as described in Section 2. Results are means ± SEM for n = 5–10 rats/group. Experimental means compared to control means: *P < .05 and **P < .01. Basal activity in the pituitary was 0.87 + 0.17 μmol/min/mg protein.

Figure 5

Dose-dependent stimulation of creatine kinase (CK) specific activity by licorice, fed daily for 3 days, in pituitary from immature female rats, compared to feeding with single dose of E₂. Rats were treated and assayed for CK activity as described in Section 2. Results are means ± SEM for n = 5 rats/group. Experimental means compared to control means: *P < .05 and **P < .01. Basal activity was 1.05 + 0.20 μmol/min/mg protein.

Figure 6

Stimulation of creatine kinase (CK) specific activity by licorice (L), glabridin (Gla) with and without E₂ in pituitary from immature (a) or from Ovx female rats (b). Rats were fed for different time periods as indicated and assayed for CK activity as described in Section 2. Results are means ± SEM for n = 5–10 rats/group. Experimental means compared to control means: *P < .05 and **P < .01. Basal activity in Pi from immature rats was 0.97 + 0.22 μmol/min/mg protein and from Ovx rats was 0.67 + 0.18 μmol/min/mg protein.

Figure 7

Dose-dependent stimulation of creatine kinase (CK) specific activity by E₂ in pituitary from immature female rats either intact (solid line) or STZ-injected animals (dotted line). Rats were treated and assayed for CK activity as described in Section 2. Results are means ± SEM for n = 5 rats/group. Experimental means compared to control means: *P < .05 and **P < .01. Basal activity in Pi from immature intact rat was 0.86 + 0.04, and from STZ rats was 0.78 + 0.12μmol/min/mg protein.

Figure 8

The effect of pretreatment with JKF and QW at 0.2 ng/rat for 24 hours (a) or for 3 days (b) on CK activity in Pi from immature female rats compared to the stimulation of E₂ at 0.5 μg/rat or 5 μg/rat and to the combination of the vitamin D analogs with E₂. Treatments were as described in Section 2. Results are expressed as the ratios between the specific activities of CK in hormone-treated and vehicle-injected control animals. The basal activity of CK in was 0.86 + 0.14 μmol/min/mg protein after 24 hours and 0.92 + 0.18 μmol/min/mg protein after 3 days, n = 5. *P < .05, **P < .01 in the difference compared to vehicle.

Figure 9

The effect of pretreatment with JKF and QW at 0.2 ng/g/rat/d for 10 weeks (a), 1 week (b) or 3 days (c) on CK activity in Pi from OVX female rats compared to the stimulation of E₂ at 5 μg/rat and to the combination of the vitamin D analogs and E₂. Treatments were as described in Section 2. Results are expressed as the ratios between the specific activities of CK in hormone-treated and vehicle-injected control animals. The basal activity of CK in was 0.76 + 0.08 μmol/min/mg protein, n = 5. *P < .05, **P < .01 in the difference compared to vehicle.

Figure 10

The effect of pretreatment with JKF and QW at 0.2 ng/g/rat/day for 3 days in immature female rats (a) or 1 week in Ovx female rats (lower panel) on CK activity compared to the stimulation by E₂ at 5 μg/rat or Ral at 500 μg/rat or both, and to the combination of the vitamin D analogs with E₂, Ral, or both. Treatments were as described in Section 2. Results are expressed as the ratios between the specific activities of CK in hormone-treated and vehicle-injected control animals. The basal activity of CK in was 0.78 + 0.10 μmol/min/mg protein for Ovx and 1.02 + 0.12 μmol/min/mg protein for immature female rats, n = 5. *P < .05, **P < .01, in the difference compared to vehicle.