Inhibitory effect of digoxin on testosterone secretion through mechanisms involving decreases of cyclic AMP production and cytochrome P450<sub>scc</sub> activity in rat testicular interstitial cells

H, Lin; Wang, Shyi Wu; Tsai, Shau‐Wei; Chen, Jiann Jong; Chiao, Yu Chung; Lu, Chien Chen; Huang, William J.S.; Wang, Guei Jane; Chen, Chieh Fu; Wang, Paulus S.

doi:10.1038/sj.bjp.0702229

Cited by 34 publications

(29 citation statements)

References 23 publications

(24 reference statements)

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“…The water bath chamber was kept saturated with 95% O 2 and 5% CO 2 . Each preparation contained approximately 20% Leydig cells [Lin et al, 1998]. …”

Section: Preparation Of Ticsmentioning

confidence: 99%

Role of testicular interstitial macrophages in regulating testosterone release in hyperprolactinemia

Huang¹,

Yeh²,

Kan³

et al. 2002

J of Cellular Biochemistry

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Hyperprolactinemia-induced hypogonadism has been linked to a dysfunction of the hypothalamus-pituitary-testis axis. The direct inhibitory effects of prolactin on the testicular release of testosterone have also been demonstrated, though their mechanisms remain unclear. Incubation of rat testicular interstitial cells (TICs) with prolactin stimulated the release of testosterone. TICs from rats with anterior pituitary-grafting-induced hyperprolactinemia release lower amounts of testosterone than controls. However, Leydig cells isolated from anterior pituitary-grafted rats release a greater amount of testosterone. These paradoxical observations have remained unexplained. This study examined the roles of testicular interstitial macrophages and of their product, tumor necrosis factor-alpha (TNF-alpha), in regulating Leydig cells under condition of hyperprolactinemia. Hyperprolactinemia was induced by grafting two anterior pituitary glands of rats under the renal capsule. Control animals were grafted with rat cortex tissue. The rats were sacrificed 6 weeks later. TICs and macrophages, and Leydig cells were isolated for in vitro incubation and drugs challenge. Testosterone released by testicular interstitial or Leydig cells was measured by radioimmunoassay. TNF-alpha concentration in the medium of TICs or macrophages was measured by enzyme-linked immunosorbent assay (ELISA). A dose-dependent stimulation of TNF-alpha secretion in the medium of TICs or macrophages by the prolactin challenge was observed. Higher amounts of TNF-alpha were released by TICs in the anterior pituitary-grafted rats than in the control group. In contrast, the release of TNF-alpha by testicular interstitial macrophages isolated from the anterior pituitary- and cortex-grafted groups was quantitatively similar. Challenge with human chorionic gonadotropin did not modify the TNF-alpha release by testicular interstitial macrophages in either group. Challenge of Leydig cells with TNF-alpha inhibited their release of testosterone stimulated by human chorionic gonadotropin, but not their basal testosterone release. These different patterns of testosterone release in TICs versus Leydig cells cultures in anterior pituitary-grafted rats may be due to the influence of testicular interstitial macrophages. These observations correlate with in vivo conditions, where prolactin increases the release of TNF-alpha by testicular interstitial macrophages, which, in turn, decreases the human chorionic gonadotropin-stimulated release of testosterone by Leydig cells. In summary, hyperprolactinemia-induced hypogonadism involves a mechanism of prolactin-originated, macrophage-mediated inhibitory regulation of testosterone release by Leydig cells. TNF-alpha, one of the cytokines secreted by macrophages, may play a key role in this mechanism.

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“…The water bath chamber was kept saturated with 95% O 2 and 5% CO 2 . Each preparation contained approximately 20% Leydig cells [Lin et al, 1998]. …”

Section: Preparation Of Ticsmentioning

confidence: 99%

Role of testicular interstitial macrophages in regulating testosterone release in hyperprolactinemia

Huang¹,

Yeh²,

Kan³

et al. 2002

J of Cellular Biochemistry

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“…The water bath chamber was kept saturated with 95% O 2 and 5% CO 2 . Each preparation was found to contain approximately 20% Leydig cells [Lin et al, 1998]. …”

Section: Preparation Of Rat Testicular Interstitial Cells (Tics)mentioning

confidence: 99%

Effects of hyperprolactinemia on testosterone production in rat Leydig cells

Huang

Yeh²,

Kan³

et al. 2000

J. Cell. Biochem.

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The pathogenesis of hyperprolactinemia (hyperPRL) induced hypogonadism has been suggested to be related with a dysfunction of hypothalamus-pituitary-testis axis. While the direct inhibitory effects of prolactin (PRL) on testosterone (T) release have been demonstrated, the mechanism is still unclear. Our previous study demonstrated a diminished T release in the testicular interstitial cells (TICs) from the anterior pituitary (AP)-grafted rats as compared with the control, and the pattern was in agreement with the in vivo model. However, TICs incubation cannot totally represent the response of the Leydig cells. Therefore, a Percoll gradient purified Leydig cell model was adopted to explore the response of T release under similar challenges in this study to investigate the effects of hyperPRL on the Leydig cells per se. HyperPRL in male rats was induced by grafting rat AP under the renal capsule. The control animals were grafted with rat brain cortex tissue (CX). Six weeks after grafting, the rats were sacrificed. Either TICs or Leydig cells were isolated, respectively, for in vitro incubation and challenge. Challenge drugs included human chorionic gonadotropin (hCG, 0.05 IU/ml), steroidogenic precursors (25-OH-cholesterol, 10(-6) M; pregnenolone, 10(-6) M), forskolin (an anenylyl cyclase activator, 10(-4) M) and 8-bromo-3':5' cyclic adenosine monophosphate (cAMP) (8-Br-cAMP 10(-4) M). T released by TICs or Leydig cells was determined by radioimmunoassay. The TICs from the AP-grafted rats showed lower levels of T release than the control group while the purified Leydig cells demonstrated a reverse pattern in response to challenges of hCG, steroidogenic precursors, forskolin and 8-Br-cAMP. In hyperPRL rats, a paradoxical pattern of T release between TICs and purified Leydig cells is observed. The purified Leydig cells from AP-grafted rats demonstrated a higher level amount of T release than the control after stimulation. The phenomenon can be attributed to the change of Leydig cell sensitivity to the stimulation after the effects of chronic hyperPRL. Moreover, another possibility is the role played by other interstitial cells to modulate steroidogenesis in Leydig cells.

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“…This inhibitory effect of bufalin is associated in part with a decrease of testicular cAMP accumulation and luteinizing hormone (LH) response to gonadotropin-releasing hormone (GnRH) . Third, we recently showed that digoxin inhibited testosterone production in rat testicular interstitial cells through attenuation of the activities of adenylyl cyclase and cytochrome P450scc [Lin et al, 1998]. In addition, digitoxin was shown to interfere the binding of dihydrotestosterone on rat ventral prostate [Pita et al, 1975] and estrogen on human uteri [Rifka et al, 1977].…”

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confidence: 98%

Inhibition of testosterone secretion by digitoxin in rat testicular interstitial cells

Wang¹,

Lin²,

Hwang³

et al. 1999

J. Cell. Biochem.

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Both in vivo and in vitro experiments were conducted to determined the effects of digitoxin on the secretion of testosterone, and its underlying mechanisms including testicular adenosine 3':5'-cyclic monophosphate (cAMP), and the activities of steroidogenic enzymes. Male rats were injected with digitoxin, human chorionic gonadotropin (hCG), or hCG plus digitoxin via a jugular catheter. Blood samples were collected immediately before and at 30 and 60 min after the challenge, and analyzed for testosterone by radioimmunoassay. In an in vitro study, rat testicular interstitial cells were isolated and incubated with digitoxin, hCG, 8-bromo-cAMP (8-Br-cAMP), digitoxin plus hCG, or digitoxin plus 8-Br-cAMP at 34 degrees C for 1 h. The media were collected and analyzed for testosterone. For studying cAMP accumulation, testicular interstitial cells were incubated for 1 h in the medium containing isobutyl-1-methylxanthine (IBMX) and different doses of digitoxin with the absence or presence of hCG. After incubation, cells were processed for determining cAMP content. Intravenous injection of digitoxin decreased hCG-stimulated, but not basal, plasma testosterone levels. Administration of digitoxin in vitro resulted in an inhibition of both basal and hCG- as well as 8-Br-cAMP-stimulated release of testosterone. In addition, digitoxin diminished hCG-stimulated cAMP accumulation in rat testicular interstitial cells. Furthermore, digitoxin inhibited the activity of cytochrome P450 side chain cleavage enzyme (P450scc) but failed to affect the activities of other steroidogenic enzymes. Taken together, these results suggest that the acute inhibitory effect of digitoxin on the testosterone production in testicular interstitial cells involves, at least partly, an inefficiency of post-cAMP events, and a decrease of P450scc activity.

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Inhibitory effect of digoxin on testosterone secretion through mechanisms involving decreases of cyclic AMP production and cytochrome P450_scc activity in rat testicular interstitial cells

Cited by 34 publications

References 23 publications

Role of testicular interstitial macrophages in regulating testosterone release in hyperprolactinemia

Role of testicular interstitial macrophages in regulating testosterone release in hyperprolactinemia

Effects of hyperprolactinemia on testosterone production in rat Leydig cells

Inhibition of testosterone secretion by digitoxin in rat testicular interstitial cells

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Inhibitory effect of digoxin on testosterone secretion through mechanisms involving decreases of cyclic AMP production and cytochrome P450scc activity in rat testicular interstitial cells

Cited by 34 publications

References 23 publications

Role of testicular interstitial macrophages in regulating testosterone release in hyperprolactinemia

Role of testicular interstitial macrophages in regulating testosterone release in hyperprolactinemia

Effects of hyperprolactinemia on testosterone production in rat Leydig cells

Inhibition of testosterone secretion by digitoxin in rat testicular interstitial cells

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Inhibitory effect of digoxin on testosterone secretion through mechanisms involving decreases of cyclic AMP production and cytochrome P450_scc activity in rat testicular interstitial cells