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Biology of Reproduction, 2000
The potential involvement of somatostatin (SRIF) in testicular function was studied by using as a... more The potential involvement of somatostatin (SRIF) in testicular function was studied by using as a model primary cultures of purified immature porcine Sertoli cells. In the present report we show that Sertoli cells express mRNA for sst2 SRIF receptor and display SRIF-sensitive adenylyl cyclase. Sensitivity of adenylyl cyclase to SRIF and its analogues is compatible with the pharmacological profile of this receptor type. Relevant cAMP production is similarly inhibited by SRIF in both basal and stimulated (by gonadotropin FSH or by forskolin) conditions. Moreover, the observed SRIF actions on Sertoli cells require functional coupling of specific membrane receptors to adenylyl cyclase via Gi proteins because pertussis toxin prevents SRIFdependent inhibition of adenylyl cyclase in either basal or FSHstimulated conditions. Given the potent antiproliferative actions of SRIF in other cell types, we further assessed the possible SRIFdependent modulation of [ 3 H]thymidine incorporation by Sertoli cells. Our data point to SRIF-mediated inhibition of both basal and FSH-stimulated [ 3 H]thymidine uptake. This inhibition of Sertoli cell proliferation is, at least in basal conditions, also blocked by pertussis toxin pretreatment. Altogether, these data suggest that SRIF may play a role as an (local) inhibitor of FSH actions in testicular development.
Molecular and cellular …, 1996
Using primary cultures of porcine Sertoli cells as a model, the effects of ovine prolactin (oPRL)... more Using primary cultures of porcine Sertoli cells as a model, the effects of ovine prolactin (oPRL) on Sertoli cell function were investigated through FSH binding. PRL treatment (0.3-S ng/ml) induced a dose-dependent increase (ED,, = 5.10-" M) of '251-FSH binding to Sertoli cells to a maximal stimulation (about 2.5-fold increase). This effect was time-dependent, being detected within 2 h (P < 0.02) after oPRL treatment and was maximal after 24 h. The effect of oPRL is probably mediated via specific PRL receptors identified by different approaches such as immunohistochemistry, binding assays and cross-linking experiments. Immunohistochemical experiments were performed using two antibodies directed against the PRL receptor. Immunoreactivity was detected both in the Sertoli cell cytoplasm and in the perinuclear area. Scatchard plots of binding studies revealed the presence of specific binding sites for PRL both in the Sertoli cell membranes and nuclear fractions with high affinity constants (Kd = 0.8 and 1.4 nM, respectively). Affinity labeling of these receptors by covalently binding to '251-oPRL and subsequent electrophoretic analysis of the labeled complexes revealed for the cell membranes, two major labeled bands of 74 and 64 kDa and three other faintly labeled bands of 190, 150 and 140 kDa. For the nuclear fractions, three major labeled bands with high molecular weights of 190, 150 and 140 kDa were observed. Taken together, the present findings suggest that Sertoli cells are potential targets for prolactin action in the porcine testis.
Biology of Reproduction, 2000
The potential involvement of somatostatin (SRIF) in testicular function was studied by using as a... more The potential involvement of somatostatin (SRIF) in testicular function was studied by using as a model primary cultures of purified immature porcine Sertoli cells. In the present report we show that Sertoli cells express mRNA for sst2 SRIF receptor and display SRIF-sensitive adenylyl cyclase. Sensitivity of adenylyl cyclase to SRIF and its analogues is compatible with the pharmacological profile of this receptor type. Relevant cAMP production is similarly inhibited by SRIF in both basal and stimulated (by gonadotropin FSH or by forskolin) conditions. Moreover, the observed SRIF actions on Sertoli cells require functional coupling of specific membrane receptors to adenylyl cyclase via Gi proteins because pertussis toxin prevents SRIFdependent inhibition of adenylyl cyclase in either basal or FSHstimulated conditions. Given the potent antiproliferative actions of SRIF in other cell types, we further assessed the possible SRIFdependent modulation of [ 3 H]thymidine incorporation by Sertoli cells. Our data point to SRIF-mediated inhibition of both basal and FSH-stimulated [ 3 H]thymidine uptake. This inhibition of Sertoli cell proliferation is, at least in basal conditions, also blocked by pertussis toxin pretreatment. Altogether, these data suggest that SRIF may play a role as an (local) inhibitor of FSH actions in testicular development.
Molecular and cellular …, 1996
Using primary cultures of porcine Sertoli cells as a model, the effects of ovine prolactin (oPRL)... more Using primary cultures of porcine Sertoli cells as a model, the effects of ovine prolactin (oPRL) on Sertoli cell function were investigated through FSH binding. PRL treatment (0.3-S ng/ml) induced a dose-dependent increase (ED,, = 5.10-" M) of '251-FSH binding to Sertoli cells to a maximal stimulation (about 2.5-fold increase). This effect was time-dependent, being detected within 2 h (P < 0.02) after oPRL treatment and was maximal after 24 h. The effect of oPRL is probably mediated via specific PRL receptors identified by different approaches such as immunohistochemistry, binding assays and cross-linking experiments. Immunohistochemical experiments were performed using two antibodies directed against the PRL receptor. Immunoreactivity was detected both in the Sertoli cell cytoplasm and in the perinuclear area. Scatchard plots of binding studies revealed the presence of specific binding sites for PRL both in the Sertoli cell membranes and nuclear fractions with high affinity constants (Kd = 0.8 and 1.4 nM, respectively). Affinity labeling of these receptors by covalently binding to '251-oPRL and subsequent electrophoretic analysis of the labeled complexes revealed for the cell membranes, two major labeled bands of 74 and 64 kDa and three other faintly labeled bands of 190, 150 and 140 kDa. For the nuclear fractions, three major labeled bands with high molecular weights of 190, 150 and 140 kDa were observed. Taken together, the present findings suggest that Sertoli cells are potential targets for prolactin action in the porcine testis.