Arachidonic acid mobilizes calcium and stimulates prolactin secretion from GH3 cells.

Because arachidonic acid and/or its metabolites may be intracellular effectors of calcium-mediated secretion, we studied whether arachidonic acid added exogenously mobilizes calcium and stimulates prolactin secretion from GH3 cells, cloned rat pituitary cells. Arachidonic acid caused efflux of 45Ca from preloaded cells and stimulated prolactin secretion. The concentration dependencies of these effects were similar; stimulation was attained with 3 microM arachidonic acid. To determine indirectly whether these effects may be caused by arachidonic acid itself, not via conversion to metabolites, two experimental approaches were used. First, inhibitors of arachidonic acid metabolism, eicosatetraynoic acid and indomethacin, did not inhibit arachidonic acid-induced prolactin secretion. And second, alpha-linolenic acid, which cannot be converted to arachidonic acid, and linoleic acid, but not saturated fatty acids of equal chain length, stimulated 45Ca efflux and prolactin secretion. These data demonstrate that arachidonic acid added exogenously causes Ca2+ mobilization and prolactin secretion from GH3 cells and suggest that arachidonic acid itself, not via metabolism, may be a cellular regulator of prolactin secretion.

Thyrotropin (TSH)-releasing hormone decreases phosphatidylinositol and increases unesterified arachidonic acid in thyrotropic cells: possible early events in stimulation of TSH secretion.

TRH stimulated the metabolism of lipids of the phosphatidylinositol (PI)-phosphatidic acid (PA) cycle and caused an increase in the level of free or unesterified arachidonic acid in mouse pituitary thyrotropic tumor (TtT) cells. In cells labeled with [32P]orthophosphate for 45 min, TRH caused a rapid specific increase in [32P]PA to 190 +/- 8% (+/- SE) of the control value at 15 sec (P less than 0.005) and in [32P]PI to 158 +/- 8% at 2 min (P less than 0.005). In cells labeled to isotopic steady state with [3H]inositol, TRH caused a decrease in [3H]PI to 92 +/- 1.8% of the control value at 1 min (P less than 0.01) and increased the level of [3H]inositolmonophosphate. In cells labeled to isotopic steady state with [14C]stearic acid, TRH caused a transient rise in [14C]diacylglycerol and a more prolonged increase in [14C]PA. In cells labeled to isotopic steady state with [3H]arachidonic acid, TRH stimulated a rise in free [3H]arachidonic acid to 210 +/- 8% of the control value at 15 sec (P less than 0.001), with a return to a level of 125 +/- 2% of the control value by 5 min. Arachidonic acid added exogenously caused efflux of 45Ca2+ from prelabeled cells and stimulated TSH secretion. Hence, in TtT cells, TRH 1) rapidly stimulated a decrease in the level of PI and increased inositolmonophosphate, diacylglycerol, and PA; and 2) caused a rapid increase in the level of free arachidonic acid. These effects may be important in stimulation of TSH secretion by TRH. Because arachidonic acid, when added exogenously, mobilized cellular Ca2+ and stimulated TSH secretion, arachidonic acid may mediate, at least in part, TRH-stimulated TSH secretion. The action of TRH on lipid metabolism in TtT cells is different from that in mammotropic pituitary cells, since TRH does not cause an increase in the level of free arachidonic acid in GH3 cells.

Copper levels in cervical mucus during normal menstrual cycles.

PIP: To establish the pattern of copper levels in cervical mucous, individual samples were taken from 10 normal women (aged 23-46), 2-3 times per week during the cycle. Analysis using a modification of the Stoner and Dasler wet ash microtechnique showed the lowest amounts of copper per 100 mg of dried ash (mean-3.2 mcg) in the ovulatory phase. The highest amount of copper was found in the secretory phase (mean 19.4 mcg). The copper level seemed to vary directly with the level of endogenous progesterone and inversely with the level of endogenous estrogen. No significant correlation between age and amount of copper secreted could be established because of the small size of the study.^ieng

Copper levels in cervical mucus of women with copper-bearing and noncopper-bearing intrauterine devices.

PIP: The copper content of individual cervical mucus samples from 50 women using conventional plastic intrauterine devices (IUDs) and from 50 women using copper-bearing IUDs containing 200 sq. mm copper wire were determined. Both groups of women showed the same pattern of copper levels as normal controls with the lowerst level of copper at ovulation. The women using the copper-bearing IUDs showed a significantly higher copper content in all phases of the cycle. Prolonged use of the copper IUD (7 weeks - 2 years) was associated with a drop in copper levels of the cervical mucus to approximately the levels in women wearing a plastic IUD. It is concluded that changes in cervical mucus copper content are due to local effects of the devices on the reproductive tract.^ieng

Variations in seminal plasma constituents from fertile, subfertile, and vasectomized azoospermic men.

PIP: Freshly ejaculated semen specimens from 20 normal fertile, 11 subfertile, and 20 vasectomized men whose semen analyses had reached complete azoospermia were compared. The mean levels of seminal acid phosphatase were significantly higher in the vasectomized men. The mean values of sialic acid in normal and postvasectomy seminal plasmas were similar, in contrast to the lower values in oligospermic men. No significant differences were observed in seminal plasma proteins, alkaline phosphatase, and fructose levels. No correlation was found between seminal alkaline phosphatase and fructose levels and sperm concentration. Azoospermia occurring after vas ligation was attributed to high phosphatase values.^ieng