The isolation and characterization of estrogen binding proteins in the pancreas of male and female hamsters

The impact of unabated stimulation by human chorionic gonadotropin on the steroid hormone environment of pregnant rats and the spontaneous expression of ovarian cysts in female progeny

Unabated stimulation by low doses of human chorionic gonadotropin (hCG) induces ovarian cysts in pregnant rats. In order to determine the impact of these in vivo treatments on the hormonal milieu of pregnancy, and the potential impact of an aberrant cystic-ovary state during pregnancy on the resulting female offspring, pregnant rats were treated with either 0 (control), 1, or 3 IU hCG twice daily for at least 9 days, beginning on day 13 of pregnancy. Serum was harvested from control and hCG treated animals on days 15, 17, 19, and 22 of pregnancy. Control pregnant rats and animals treated with 1 IU hCG shared similar serum profiles for progesterone (P4), androstenedione (A4), 5alpha-androstane-3alpha,17beta-diol (3alpha-diol), androsterone (A5), and estrone (E1) between days 15 and 22 of pregnancy. Testosterone serum concentrations were similar for control and 1 IU hGG-treated pregnant rats between days 15 and 19 of pregnancy; whereas, on day 22, 1 IU hGG-treated pregnant rats displayed lower serum testosterone than control pregnant rats (P < or = 0.05). In contrast, serum estradiol (E2) concentrations for 1 IU hCG- treated pregnant rats were greater than E2 values observed for control rats on days 15-19 of pregnancy (P < or = 0.05). Serum testosterone and 3alpha-diol values for 3 IU hCG-treated pregnant rats differed from those of control pregnant rats only on day 19 when these values were transiently greater for these hCG-treated animals compared with serum values for control pregnant rats (P < or = 0.05). Serum A4 values for 3 IU hCG-treated pregnant rats were elevated compared to values for control pregnant rats only on days 15 and 17 (P < or = 0.05). In contrast, serum E1, A5, and E2 were elevated on days 19-22, 17-22, and 15-22, respectively, in 3 IU hCG-treated pregnant rats compared to control pregnant rats (P < or = 0.05). No pups from control pregnant rats displayed ovarian cysts during the time they were observed postnatally. In contrast, 6 of 25 pups from 3 IU hCG-treated pregnant rats displayed cystic ovaries, without corpora lutea, on day 55 of age. Serum steroid concentrations for these cyst-bearing progeny were similar to those of female progeny from control pregnant rats, whereas female progeny without ovarian cysts from 3 IU hCG-treated pregnant rats displayed differences in serum steroid values from those of progeny from control pregnant rats (P < or = 0.05). The data support the concept that an aberrant, yet physiologic hormonal environment associated with the induction of ovarian cysts during pregnancy in rats, can lead to the spontaneous establishment of an ovarian cystic state in at least a subset of the female progeny. Further, the date suggest that tonically increased ovarian estrogen production during pregnancy, reflected by tonically elevated peripheral serum estrogen concentrations, may play a pivotal role in the etiology of an ovarian cystic state in this subset of daughters from hCG-induced, cyst-bearing pregnant rats.

Specific binding of cholecystokinin, estradiol and somatostatin to human pancreatic cancer xenografts

We recently reported that human pancreatic cancers differentially respond to the growth inhibitory effects of an estradiol (E2) receptor antagonist, tamoxifen, and a long-acting analogue of somatostatin, Sandostatin. In the present study two human pancreatic cancers, established as xenografts in nude mice, were examined as representative of cancers that respond to either tamoxifen (PGER) or Sandostatin (SKI), for the presence of binding sites for various hormones. Male nude mice were inoculated with either SKI or PGER, by passage of tumor chunks (3 mm2) to the interscapular region. Tumors, obtained from mice after approximately 30 days of in vivo growth, were analyzed for binding to cholecystokinin-octapeptide (CCK), somatostatin and E2, by published procedures, using either crude tumor membranes (CCK), cytosol and nuclear fractions (E2), or cryostat sections of whole tumors (somatostatin). SKI was highly positive for high-affinity (Kd = approximately 1 nM) CCK binding sites at the time of resection with a binding capacity of approximately 1000 fmol/mg protein. With increasing passages, the total number of high-affinity binding sites for CCK, were reduced to non-detectable levels in SKI tumors, while non-saturable binding (Kd = greater than 10 nM) became increasingly evident. Early passages of PGER tumors were similarly positive for high-affinity binding sites for CCK, that steeply declined with increasing passages. Specific binding sites for E2, were observed only in the cytosolic fractions of PGER, with a high binding affinity (Kd = approximately 0.05 nM) and a low binding capacity (15 +/- 3 fmol/mg cytosolic proteins), at all passages examined; E2 binding sites were not detected in cytosolic and nuclear fractions of SKI and in the nuclei of PGER, at all passages. SKI and PGER at different passages were examined for somatostatin binding, and both the early and late passages of PGER were devoid of somatostatin binding sites, while SKI tumors were positive for them. Based on the above results, it appears likely that Sandostatin directly inhibited the growth of SKI tumors, since SKI was positive for somatostatin binding sites; it appears less likely that Sandostatin indirectly mediated its inhibition by attenuating possible stimulatory effects of CCK. Growth inhibitory effects of tamoxifen on PGER were apparently via E2 binding sites, since only the tumors positive for E2 binding sites (PGER) responded to tamoxifen; it remains to be determined if tamoxifen can exert additional effects independent of E2 binding sites on pancreatic cancers.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of estradiol on pancreatic amylase and cholecystokinin binding in ovariectomized guinea pigs

The effect of estradiol (E2) on amylase content and on basal and stimulated amylase release from the pancreatic acini was examined in relation to its effects on cholecystokinin (CCK)-receptor (R) levels. Guinea pigs were ovariectomized (OVX) and a week later administered either E2 (10 micrograms/kg) (Treated, T) or vehicle (corn oil) (Control, C) 0.2 ml/day s.c. After 7 days of injections, animals were killed, pancreata weighed and basal and stimulated amylase release from pancreatic acini measured. Receptors for CCK were measured on pancreatic membranes. Chronic administration of E2 resulted in a significant decrease in: (1) pancreatic weight (0.96 +/- 0.04, T vs 1.142 +/- 0.046 g, C); (2) total pancreatic DNA content (5.74 +/- 0.37, T vs 6.81 +/- 0.16 mgs, C); (3) total amylase content in pancreata (2081 +/- 307, T vs 3795 +/- 442 I.U., C); (4) absolute value of basal amylase release (6.57 +/- 1.4, T vs 11.8 +/- 1.9 I.U./incubate, C); and (5) absolute value of amylase release stimulated by increasing doses (0.01-1000 nM) of CCK in T vs C animals. On the other hand, the amylase release in response to greater than 0.5 nM of CCK, expressed as a percentage of the total amylase content, was significantly increased in T vs C animals, which may be related to a significant rise in the concentration (fmol/mg protein) of CCK-receptors (629.8 +/- 65.9, T vs 313.4 +/- 92.7 fmol, C). Concentration of DNA/unit pancreatic weight and basal amylase release expressed as a percentage of total content, however, was similar in the C and T guinea pigs, while concentration of amylase and CCK-receptors/unit pancreatic weight remained significantly different in the two groups of animals. These results suggest that E2 may have more than one effect on the pancreas in vivo, including a significant reduction in pancreatic growth and amylase concentration/cell and an up-regulation of CCK-receptors/cell.