I see no citation. Where is this studdy published? I have found little data to support beta blockers lower T, and some studies suggest they may increase T:
Horm Metab Res. 2000 Jul;32(7):259-64. Links
Propranolol stimulates histone phosphorylation by a putative PK-C in partially purified homogenate of rat testicular interstitial cells. A possible mechanism for increased testosterone secretion by propranolol.
* Wanderley MI,
* Udrisar DP,
* Martins MC,
* Antunes-Rodrigues J.
Departamento de Fisiologia e Farmacologia, Universidade Federal de Pernambuco, Recife, Brasil.
miw@npd.ufpe.br
The beta-adrenoceptor blocker propranolol stimulated testosterone secretion by rat testicular interstitial cells (Leydig cell-enriched preparation) in vitro at concentrations ranging from 10(-5) M to 10(-4) M. Treatment of these cells with H7 (20 microM), an inhibitor of protein kinase C, reduced the stimulatory effect of L-propranolol on testosterone secretion by about 5-fold. At concentrations ranging from 31.25 microM to 1000 microM, L-propranolol reduced [3H]phorbol 12,13-dibutyrate binding (IC50 = 75 microM) to rat testicular interstitial cells. At similar concentrations, L-propranolol displaced the binding of [3H]phorbol 12,13-dibutyrate to the homogenate of these cells by only 5%. These findings suggest that the effect of L-propranolol on [3H]phorbol 12,13-dibutyrate binding could be indirect, possibly by increasing the concentration of a chemical mediator interacting with the regulatory domain of protein kinase C. At even lower concentrations (10(-9) M to 10(-7) M), propranolol added directly to the reaction mixture with protein kinase C partially purified from rat testicular interstitial cells increases the phosphorylation of histone. This phosphorylation was comparable to that obtained with (25 microg/ml) phosphatidylserine. The D- and L-stereoisomers of propranolol were equally active. A complete reversal of this propranolol effect on histone phosphorylation was achieved with (20 microM) H-7. In the absence of Ca2+, propranolol was not able to phosphorylate the histone. Taken together, these results suggest that protein kinase C could be the putative kinase involved in this reaction and that its activation by propranolol may be due to interaction of the drug with the regulatory domain of the enzyme at a site differing from the site of interaction with phorbol 12,13-dibutyrate. The ability of propranolol to activate the putative protein kinase C could be related to its stimulatory effect on testosterone secretion by Leydig cells.
and
1: Braz J Med Biol Res. 1996 Nov;29(11):1567-71. Links
Propranolol stimulates testicular interstitial fluid formation and testosterone secretion in rats.
* Martins MC,
* Udrisar DP,
* Wanderley MI.
Departamento de Fisiologia, Universidade Federal do Piaui Teresina, Brasil.
We investigated the effect of intratesticularly injected propranolol on testicular interstitial fluid (TIF) formation and on testosterone levels in the TIF of intact adult male Wistar rats (4-9 rats per group). dl-propranolol at doses of 0.6, 1.2, or 6.0 mg/kg was injected into the left (L) testis whereas the right (R) testis (control testis) received vehicle. dl-propranolol (6.0 mg/kg) caused a significant increase in both TIF volume (329%) and TIF levels of testosterone (257%) in the L testis but not in the R (control) testis 3 h post-injection. In rats treated simultaneously with human chorionic gonadotropin (hCG, 5 IU/rat, sc) the same dose or propranolol (6.0 mg/kg) significantly increased the stimulatory effect of hCG on testosterone secretion by 1.8-fold, but hCG did not modify the stimulatory effect of propranolol on TIF volume. These results demonstrate a direct stimulatory effect of propranolol on TIF volume and testosterone secretion, both under basal and hCG-stimulated conditions.
and
Andrologia. 1997 Mar-Apr;29(2):109-14. Links
Propranolol treatment affects ventral prostate blood vessels and serum testosterone concentrations in adult rats.
* Plecas B,
* Glavaski A,
* Solarovic T.
Department of Physiology, Faculty of Pharmacy, Belgrade, Yugoslavia.
The influence of prolonged beta-adrenergic receptor blockade on stereologic parameters of the ventral prostate and serum testosterone concentrations was examined in adult rats injected with propranolol (0.1 or 0.4 mg kg-1/day) for 15 or 30 consecutive days. Both doses of propranolol reduced the relative and absolute volume of the ventral prostate blood vessels. This effect was prevented by simultaneous administration of urapidil, an alpha 1-adrenergic receptor antagonist, indicating that a compensatory vasoconstriction took place as a consequence of propranolol treatment. Serum testosterone concentration was significantly increased following the 30-day application of the lower dose of the drug. These results show that prolonged administration of propranolol, although not affecting the epithelial component of the gland, may indirectly influence prostatic function by reducing the blood flow to the gland.
Bottom line is that it's unclear if beta blockers lower T at this time and studies are lacking and or conflicting.
