Effects of selective estrogen receptor modulators on plasma membrane estrogen receptors and catecholamine synthesis and secretion in cultured bovine adrenal medullary cells.

We previously reported the occurrence and function of plasma membrane estrogen receptors in cultured bovine adrenal medullary cells. Here we report the effects of raloxifene and tamoxifen, selective estrogen receptor modulators, on plasma membrane estrogen receptors and catecholamine synthesis and secretion in these cells. Raloxifene caused dual effects on the specific binding of [(3)H]17ß-estradiol to the plasma membranes isolated from bovine adrenal medulla; that is, it had a stimulatory effect at 1.0 - 10 nM but an inhibitory effect at 1.0 - 10 µM, whereas tamoxifen (1.0 nM - 10 µM) increased binding at all concentrations (except for 100 nM). Tamoxifen at 100 nM caused a significant increase in basal (14)C-catecholamine synthesis from [(14)C]tyrosine, whereas tamoxifen and raloxifene at higher concentrations attenuated basal and acetylcholine-induced (14)C-catecholamine synthesis. Raloxifene (0.3, 1.0, and 3 - 100 µM) and tamoxifen (10 - 100 µM) also suppressed catecholamine secretion and (45)Ca(2+) and (22)Na(+) influx, respectively, induced by acetylcholine. Raloxifene (1.0 µM) inhibited Na(+) current evoked by acetylcholine in Xenopus oocytes expressing α4ß2 neuronal nicotinic acetylcholine receptors. The present findings suggest that raloxifene and tamoxifen at low concentrations allosterically modulate plasma membrane estrogen receptors and at high concentrations inhibit acetylcholine-induced catecholamine synthesis and secretion by inhibiting Na(+) and Ca(2+) influx in bovine adrenal medulla.

Stimulatory effect of nobiletin, a citrus polymethoxy flavone, on catecholamine synthesis through Ser19 and Ser40 phosphorylation of tyrosine hydroxylase in cultured bovine adrenal medullary cells.

We previously reported the dual effects of nobiletin, a compound of polymethoxy flavones found in citrus fruits, on catecholamine secretion in cultured bovine adrenal medullary cells. Here, we report the effects of nobiletin on catecholamine synthesis in the cells. Nobiletin increased the synthesis of (14)C-catecholamines from [(14)C]tyrosine in a time (20-30 min)- and concentration (1.0-100 µM)-dependent manner. Nobiletin (10-100 µM) also activated tyrosine hydroxylase activity. The stimulatory effect of nobiletin on (14)C-catecholamine synthesis was not observed when extracellular Ca(2+) was not present in the incubation medium. Protein kinase inhibitors including H-89, an inhibitor of cyclic AMP-dependent protein kinase, and KN-93, an inhibitor of Ca(2+)/calmodulin-dependent protein kinase II, suppressed the stimulatory effects of nobiletin on catecholamine synthesis as well as tyrosine hydroxylase activity. Nobiletin also induced the phosphorylation of tyrosine hydroxylase at Ser(19) and Ser(40). Nobiletin (1.0-100 µM) inhibited (14)C-catecholamine synthesis induced by acetylcholine. The present findings suggest that nobiletin, by itself, stimulates catecholamine synthesis through tyrosine hydroxylase phosphorylation at Ser(19) and Ser(40), whereas it inhibits catecholamine synthesis induced by acetylcholine in bovine adrenal medulla.

Pentazocine inhibits norepinephrine transporter function by reducing its surface expression in bovine adrenal medullary cells.

(±)-Pentazocine (PTZ), a non-narcotic analgesic, is used for the clinical management of moderate to severe pain. To study the effect of PTZ on the descending noradrenergic inhibitory system, in the present study we examined the effect of [(3)H]norepinephrine (NE) uptake by cultured bovine adrenal medullary cells and human neuroblastoma SK-N-SH cells. (-)-PTZ and (+)-PTZ inhibited [(3)H]NE uptake by adrenal medullary cells in a concentration-dependent (3-100 µM) manner. Eadie-Hofstee analysis of [(3)H]NE uptake showed that both PTZs caused a significant decrease in the V(max) with little change in the apparent K(m), suggesting non-competitive inhibition. Nor-Binaltorphimine and BD-1047, κ-opioid and σ-receptor antagonists, respectively, did not affect the inhibition of [(3)H]NE uptake induced by (-)-PTZ and (+)-PTZ, respectively. PTZs suppressed specific [(3)H]nisoxetine binding to intact SK-N-SH cells, but not directly to the plasma membranes isolated from the bovine adrenal medulla. Scatchard analysis of [(3)H]nisoxetine binding to SK-N-SH cells revealed that PTZs reduced the B(max) without changing the apparent K(d). Western blot analysis showed a decrease in biotinylated cell-surface NE transporter (NET) expression after the treatment with (-)-PTZ. These findings suggest that PTZ inhibits the NET function by reducing the amount of NET in the cell surface membranes through an opioid and σ-receptor-independent pathway.

Prenatal spontaneous disruption of the dividing membrane in monochorionic diamniotic twins detected at the time of fetoscopic laser photocoagulation.

Spontaneous antepartum rupture of the dividing membrane occurring in monochorionic diamniotic twins (MD twin) is an extremely rare complication and difficult to diagnose prenatally. We present a case of pseudo-monoamniotic twins derived from an MD twin gestation, which was suspected by ultrasound and was confirmed by antepartum fetoscopy. A 28-year-old woman, gravida 1, para 1 at 24 weeks of gestation was referred because of suspected polyhydroamnios in an MD twin. Ultrasound suggested twin-twin transfusion syndrome stage III, spontaneous rupture of the dividing membranes and cord entanglement. Fetoscopic laser photocoagulation (FLP) was performed using the Nd:YAG laser on 12 placental vascular connections. Fetoscopy revealed the spontaneous rupture of the dividing membrane and cord entanglement. The remainder of the pregnancy was managed as a monoamniotic twin gestation. Elective cesarean section was performed at 32 weeks of gestation following antenatal steroids and concordantly grown healthy male infants were delivered.

Low-grade endometrial stromal sarcoma recurring with multiple bone and lung metastases: report of a case.

BACKGROUND: Approximately 50% of patients with low-grade endometrial stromal sarcoma (ESS) develop recurrent disease, mainly in lung or pelvis. Bone metastasis of low-grade ESS is an extremely rare phenomenon. CASE: A 63-year-old Japanese female developed multiple bone and lung metastases 18 years after initial treatment for low-grade ESS. Bone scintigram showed a high uptake area at thoracic spine (Th6, Th8-9 and Th12), right 9th rib, iliac bone, and sacrum. Radiation therapy with Liniac of 4500cGy to the Th6 vertebra and Liniac of 4200cGy to sacrum was performed for the palliation of the pain. Radiotherapy was effective for the pain relief, although the size of recurrent tumor was unchanged. CONCLUSION: This is the first detailed reported case of multiple bone recurrence in a patient with low-grade ESS. The long-term follow-up after treatment is recommended.