3. Results
3.1. Effects of b-carotene either in DMSO or THF on progesterone production Luteal cells were cultured for 7 days in the absence or presence of b-carotene
dissolved in organic solvents. Each treatment consisted of six separate cell wells. Ž
. Treatment of cells with 1 DMSO alone or with b-carotene 5 mmolrl in DMSO both
Ž .
resulted in significant P - 0.01
stimulation. However, a higher concentration of Ž
. Ž
. b-carotene 50 mmolrl in DMSO did not affect progesterone production Fig. 1a . A
5-mmolrl b-carotene in THF did not alter progesterone production but 50 mmolrl in Ž
. Ž
. THF resulted in significant inhibition P - 0.02 on days 3 and 7 Fig. 1b .
3.2. HDL and b-carotene The b-carotene concentrations of HDL isolated from serum containing high or low
b-carotene were 12.4 and 0.44 mgrmg cholesterol, respectively. Mean b-carotene
Ž . Fig. 1. a Effect of b-carotene dissolved in DMSO on progesterone production by luteal cells in culture. Cells
Ž .
Ž .
Ž were cultured in medium under basal conditions I , with 1 DMSO dotted square , 5 mmolrl square with
. Ž
. three jagged diagonal lines from top right to bottom left or 50 mmolrl checkered square b-carotene in 1
Ž . DMSO. b Effect of b-carotene dissolved in THF on progesterone production by luteal cells in culture. Cells
Ž .
Ž were cultured in medium under basal conditions I , with 0.1 THF square with three jagged diagonal lines
. Ž
. from top left to bottom right , 5 mmolrl square with one vertical line in the middle or 50 mmolrl b-carotene
Ž .
Ž .
B in 0.1 THF. Within each day, groups with different letters are significantly different P - 0.05 .
Table 1 Uptake and depletion of b-carotene by cultured luteal cells
Ž The cells were incubated with or without HDL containing high b-carotene concentration 50 mg cholesterolrml;
. Ž
. 620 mg b-carotenerml up to 6 days. Cells were treated with HDL on days 1 and 2 analysed on day 3 or 3
Ž .
and 5 analysed on day 6 . Results are the meansSEM of three independent experiments. Different
Ž .
superscripts denote significant differences between groups P - 0.01 within columns.
6
Ž .
b-Carotene content of luteal cells ngr10 cells SEM Control
HDL
a a
Day 0 373.183
373.183
b c
Day 3 151.439
1654.4126
d e
Day 6 49.98.5
2030.3171
Ž .
concentration of bovine corpus luteum was 52.13 mgrg n s 39 . b-Carotene content was quite different from animal to animal and ranged from 7.5 to 200 mgrg. This
variation appeared to be correlated with time of year in which the samples were Ž
. collected Arkan and Rodway, in preparation .
3.3. Uptake and depletion of b-carotene by luteal cells in culture As seen in Table 1, uptake and depletion of b-carotene by luteal cells changed in
parallel with increased incubation time. b-Carotene concentration in cells increased 5.5-fold by day 6 when compared with the initial level. In contrast, the concentration in
Ž .
control cells decreased to 14 of starting values during the same period P - 0.01 . 3.4. Effect of b-carotene associated with HDL on progesterone production
Luteal cells were incubated for 11 days in medium supplemented with bovine HDL Ž
. preparations containing equal concentrations of cholesterol 25 mgrml but high or low
Fig. 2. Effect of b-carotene associated with HDL on progesterone secretion by luteal cells in culture. Luteal Ž
. Ž
. Ž
. cells were incubated without I or with HDL 25 mg cholesterolrml containing low checkered square or
Ž .
high B b-carotene concentrations. Treatment was started on day 3. Within each day, groups with different Ž
. letters are significantly different P - 0.05 .
Ž .
b-carotene 12.4 or 0.44 mgrmg of cholesterol . Both HDLs significantly stimulated Ž
. progesterone production
P - 0.01 but the high b-carotene HDL was significantly Ž
. Ž
. P - 0.02 more effective than the low b-carotene HDL by day 11 Fig. 2 . Both
Ž .
dbcAMP and bLH alone significantly P - 0.01 stimulated progesterone production.
This stimulation was increased when either high or low b-carotene HDL was included. Ž
. However, the high b-carotene HDL gave significantly
P - 0.01 less additional
Ž .
stimulation than did the low Fig. 3 . 3.5. Effect of bLH and dbcAMP on depletion of b-carotene by luteal cells
Ž .
Depletion of b-carotene in the luteal cells was significantly higher P - 0.05 in
Ž .
bLH- and dbcAMP-treated cells than the control cells in both groups Table 2 .
However, depletion was faster in bLH-treated cells than dbcAMP-treated cells. b-Caro-
Ž . Fig. 3. a Effect of b-carotene with or without bLH on progesterone production by luteal cells. Cells were
Ž .
Ž . Ž
. Ž
. incubated without I or with bLH 100 ngrml
dotted square , bLHqHDL 25 mg cholesterolrml Ž
. Ž
containing low square with three jagged diagonal lines from top right to bottom left or high checkered .
Ž . Ž
. Ž
. Ž square b-carotene concentrations. b Cells were incubated without I or with dbcAMP 1 mmolrl square
. Ž
with three jagged diagonal lines from top left to bottom right , dbcAMPqHDL containing low square with .
Ž .
one horizonal line in the middle or high B b-carotene concentrations. Treatment was started on day 3. Ž
. Within each day, groups with different letters are significantly different P - 0.05 .
Table 2 Effect of bLH and dbcAMP on depletion of b-carotene by luteal cells
Ž .
Cells were pre-cultured with HDL containing high b-carotene concentrations 50 mg cholesterolrml for
Ž .
Ž .
either 2 or 4 days incubated then with or without dbcAMP 1 mmolrl or LH 100 ngrml for a further 2 days. b-Carotene content of cells was measured by HPLC. Results are the meansSEM of three independent
Ž .
experiments. Different superscripts denote significant differences between groups P - 0.05 within columns.
6
Ž .
b-Carotene content of luteal cells ng per 10 cells SEM Days of b-carotene treatment
2 4
a c
Control 939.1829
1174.4152
ab a
dbcAMP 807.2671
934.7543
b ab
LH 713.8528
831.0371
tene content was also effected by treatment time. Content of b-carotene was higher in Ž
. the control group treated for 4 days than the control group treated for 2 days P - 0.02 .
4. Discussion
Kategori