Effect of a dopamine agonist on luteinizing hormone receptors, cyclic AMP production and steroidogenesis in rat Leydig cells

Paternal exposure to bupropion affects postnatal development in the offspring

The aim of this study was to evaluate whether paternal exposure to bupropion hydrochloride (BUP), an inhibitor of dopamine and noradrenaline reuptake, would affect the postnatal development of offspring. Male mice were divided into a BUP-treated (40mgkg-1day-1 by gavage, 45 days) or control (saline by gavage, 45 days) group (n=20 in each group). From Day 35 to Day 45 of treatment, males were allowed to mate with drug-naïve female mice. Postnatal development of the offspring (both sexes) was evaluated from Postnatal day (PND) 1 to PND60. Physical development parameters (weight gain, body length, incisor eruption, pinna detachment), anogenital distance, vaginal opening, reflexes (palmar grasp, surface righting, negative geotaxis and adult gait) and some behavioural parameters (locomotor activity and anxiety-like behaviour) were altered in the offspring of BUP-treated males. The results demonstrate that paternal exposure to BUP induces long-lasting changes in the postnatal development of the offspring.

Bupropion promotes alterations in the spermatogenesis of mice and congenital malformations in the offspring

Bupropion hydrochloride (BUP) has been associated with male sexual dysfunction. The aim of this study was to evaluate the effects of BUP on the reproductive function of male mice and to evaluate offspring development. The mice were distributed into BUP group (40 mg kg−1) and control group (saline). On Day 35 of treatment the males were placed to mate with females and then killed on Day 46 for evaluation of reproductive function. On Day 18 of pregnancy, pregnant females were killed for evaluation of congenital malformations in the offspring. The BUP group showed a decrease in the Johnsen score (Control, 9.354 ± 0.092; BUP, 7.615 ± 0.147), Sertoli (Control, 5.623 ± 0.184; BUP, 4.215 ± 0.097) and Leydig (Control, 11.430 ± 0.817; BUP, 7.531 ± 0.213) cell counts, testosterone levels (Control, 783.5 ± 154.2 ng dL−1; BUP, 201.4 ± 54.8 ng dL−1) and sperm production (Control, 2.852 ± 0.211; BUP, 1.988 ± 0.116) and increased morphological alterations of the sperm head (Control, 8.134%; BUP, 10.423%) and tail (Control, 4.96%; BUP, 16.211%). The congenital malformations observed in BUP-derived offspring were: kyphosis (Control, 0.00%; BUP, 5.26%), retroverted rear legs (Control, 14.43%; BUP, 53.68%), incomplete ossification of the supraoccipital and exoccipital (Control, 21.82%; BUP, 86.00%) and sternum (Control, 25.45%; BUP, 82.00%). BUP had toxic effects on testicular function and teratogenic potential.

Mechanisms of digoxin and digitoxin on the production of corticosterone in zona fasciculata-reticularis cells of ovariectomized rats

Previous studies have indicated that digoxin (DG) inhibits testosterone production by rat testicular interstitial cells through both in vivo and in vitro experiments. DG and digitoxin (DT), but not ouabain, inhibit the progesterone, pregnenolone, and corticosterone secretion by rat granulosa cells, luteal cells, and zona fasciculata-reticularis (ZFR) cells, respectively. However, the effect of DG and DT on the enzyme kinetics of cytochrome P450 side chain cleavage enzyme (P450scc), the protein expression of P450scc and steroidogenic acute regulatory protein (StAR), and mRNA expression of StAR are unclear. ZFR cells were prepared from adrenocortical tissues of ovariectomized rats, and then challenged with adrenocorticotropin (ACTH), 8-Br-cAMP, forskolin, A23187, cyclopiazonic acid (CPA), nicotinic acid adenine dinucleotide phosphate (NAADP), trilostane, 25-OH-Cholesterol, progesterone, or deoxycorticosterone in the presence of DG, DT, or ouabain for 1 h. Enzyme kinetics of P450scc, protein expression of acute regulatory protein (StAR) and P450scc, and mRNA expression of StAR were investigated. DG and DT but not ouabain suppressed basal and other evoked-corticosterone release significantly. DG and DT also inhibited pregnenolone production. The Vmax of the DG and DT group was the same as the control group, but the Km was higher in DG- and DT-treated group than in control group. DT and ouabain significant suppressed mRNA expression of StAR. DG and DT had no effect on the P450scc and StAR protein expression at basal state, but diminished ACTH-induced StAR protein expression to basal level. These results indicated that DG and DT have an inhibitory effect on corticosterone production via a Na+, K+-ATPase-independent mechanism by diminishing actions on cAMP-, Ca2+-pathway, competitive inhibition of P450scc enzyme and reduction of StAR mRNA expression.

Season of the year influences testosterone secretion in bulls administered luteinizing honrmone

The objective of the present study was to evaluate the secretion of testosterone (T) in bulls in response to the administration of varying doses of bovine LH (bLH) during the four seasons of the year. Five adult bulls (4 yr of age) were treated with an amount of bLH that was estimated to induce a 5 ng/mL amplitude pulse of LH in blood serum on five consecutive days around the spring equinox, summer solstice, fall equinox, and winter solstice. Five hours after this dose, bulls were treated with bLH in amounts that were estimated to induce a 0.25, 0.5, 1, 2, or 4 ng/mL amplitude LH pulse in blood serum in a Latin square design. Blood samples were collected for 5 h after administration of a dose of bLH that was estimated to induce the 5-ng amplitude LH pulse, and for 3 h after administration of the variable doses of bLH, and were then assayed for concentrations of T. Average concentrations and amplitude of T release after doses of bLH that were estimated to induce the 5-ng amplitude LH pulses were greater during the spring and summer than during the winter (P < 0.05). The area under the release curve (AUC) was greater during the spring than during the winter (P < 0.05). During the 3 h after treatment with the variable doses of bLH, T response was affected by dose (P < 0.001) and season (P < 0.001), but there was no dose x season interaction. Testosterone response increased in a dose-dependent fashion for all variables studied. The greatest average concentrations of T and AUC were observed in the spring compared with the fall and winter (P < 0.05). These data support our working hypothesis that testes of bulls are more responsive in releasing T in response to bLH stimulation in the spring and summer compared with the winter; however, there were no changes in sensitivity of the testes to LH during different seasons of the year as indicated by the lack of a dose of bLH x season interaction.

Progesterone attenuates the inhibitory effects of cardiotonic digitalis on pregnenolone production in rat luteal cells

Previous studies have shown that digoxin decreases testosterone secretion in testicular interstitial cells. However, the effect of digoxin on progesterone secretion in luteal cells is unclear. Progesterone is known as an endogenous digoxin-like hormone (EDLH). This study investigates how digitalis affected progesterone production and whether progesterone antagonized the effects of digitalis. Digoxin or digitoxin, but not ouabain, decreased the basal and human chorionic gonadotropin (hCG)-stimulated progesterone secretion as well as the activity of cytochrome P450 side chain cleavage enzyme (P450scc) in luteal cells. 8-Br-cAMP and forskolin did not affect the reduction. Neither the amount of P450scc, the amount of steroidogenic acute regulatory (StAR) protein, nor the activity of 3beta-hydroxysteroid dehydrogenase (3beta-HSD) was affected by digoxin or digitoxin. Moreover, in testicular interstitial and luteal cells, progesterone partially attenuated the reduction of pregnenolone by digoxin or digitoxin and the progesterone antagonist, RU486, blocked this attenuation. These new findings indicated that (1) digoxin or digitoxin inhibited pregnenolone production by decreasing the activity of P450scc enzyme, but not Na(+)-K(+)-ATPase, resulting in a decrease on progesterone secretion in rat luteal cells, and (2) the inhibitory effect on pregnenolone production by digoxin or digitoxin was reversed partially by progesterone. In conclusion, digoxin or digitoxin decreased progesterone production via the inhibition of pregnenolone by decreasing P450scc activity. Progesterone, an EDLH, could antagonize the effects of digoxin or digitoxin in luteal cells.

Direct inhibitory effect of digitalis on progesterone release from rat granulosa cells

Digoxin (10(-7) - 10(-5) M) or digitoxin (10(-7) - 10(-5) M) decreased the basal and human chorionic gonadotropin (hCG)-stimulated release of progesterone from rat granulosa cells. Digoxin (10(-5) M) or digitoxin (10(-5) M) attenuated the stimulatory effects of forskolin and 8-bromo-cyclic 3' : 5'-adenosine monophosphate (8-Br-cAMP) on progesterone release from rat granulosa cells. Digoxin (10(-5) M) or digitoxin (10(-5) M) inhibited cytochrome P450 side chain cleavage enzyme (cytochrome P450(scc)) activity (conversion of 25-hydroxyl cholesterol to pregnenolone) in rat granulosa cells but did not influence the activity of 3beta-hydroxysteroid dehydrogenase (3beta-HSD). Neither progesterone production nor P450scc activity in rat granulosa cells was altered by the administration of ouabain. Digoxin (10(-5) M) or digitoxin (10(-5) M), but not ouabain, decreased the expression of P450scc and steroidogenic acute regulatory (StAR) protein in rat granulosa cells. The present results suggest that digoxin and digitoxin decrease the progesterone release by granulosa cells via a Na(+),K(+)-ATPase-independent mechanism involving the inhibition of post-cyclic AMP pathway, cytochrome P450scc and StAR protein functions.

Inhibition of salmon calcitonin on secretion of progesterone and GnRH-stimulated pituitary luteinizing hormone

The effects of salmon calcitonin (sCT) on the production of progesterone and secretion of luteinizing hormone (LH) were examined in female rats. Diestrous rats were intravenously injected with saline, sCT, human chorionic gonadotropin (hCG), or hCG plus sCT. Ovariectomized (Ovx) rats were injected with saline or sCT. In the in vitro experiments, granulosa cells and anterior pituitary glands (APs) were incubated with the tested drugs. Plasma LH levels of Ovx rats were reduced by sCT injection. Administration of sCT decreased the basal and hCG-stimulated progesterone release in vivo and in vitro. 8-Bromo-cAMP dose dependently increased progesterone production but did not alter the inhibitory effect of sCT. H-89 did not potentiate the inhibitory effect of sCT. Higher doses of 25-hydroxycholesterol and pregnenolone stimulated progesterone production and diminished the inhibitory effects of sCT. sCT did not decrease basal release of LH by APs, but pretreatment of sCT decreased gonadotropin-releasing hormone (GnRH)-stimulated LH secretion. These results suggested that sCT inhibits progesterone production in rats by preventing the stimulatory effect of GnRH on LH release in rat APs and acting directly on ovarian granulosa cells to decrease the activities of post-cAMP pathway and steroidogenic enzymes.