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A couple of quick saw palmetto studies of interest


#1

1: Prostate. 2006 Feb 1;66(2):115-23. Links

Saw palmetto is an indirectly acting sympathomimetic in the rat-isolated prostate gland.
Cao N,
Haynes JM,
Ventura S.
Prostate Research Co-Operative, Faculty of Pharmacy, Monash University, Parkville, Victoria, Australia.

BACKGROUND: To investigate whether saw palmetto that inhibits alpha1-adrenoceptor binding in vitro affects contractility of the rat prostate gland. METHODS: The effects of a commercially available saw palmetto extract were examined on the contractility of rat-isolated prostate glands. The extract was tested in the presence and absence of phentolamine, prazosin, yohimbine, propranolol, hexamethonium, cocaine, desipramine, nifedipine, guanethidine, atropine, and alpha,beta-methylene ATP to evaluate the mechanism of action. Isolated preparations of rat vas deferens and bladder were used for comparison. RESULTS: Unexpectedly, saw palmetto extract caused contractions of the rat prostate gland that could be attenuated by prazosin, phentolamine, nifedipine, guanethidine, cocaine, and desipramine but not by any of the other pharmacological tools. Similar contractile effects were observed in rat-isolated vas deferens preparations but not in rat-isolated bladder preparations. CONCLUSIONS: In the rat prostate gland, saw palmetto extract causes indirect alpha1-adrenoceptor-mediated contractions via the release of noradrenaline from sympathetic neurons. Copyright 2005 Wiley-Liss, Inc.

PMID: 16114061 [PubMed - indexed for MEDLINE]

: Prostate. 1999 Feb 15;38(3):208-15. Links

Saw palmetto extracts potently and noncompetitively inhibit human alpha1-adrenoceptors in vitro.
Goepel M,
Hecker U,
Krege S,
Rubben H,
Michel MC.
Department of Urology, University of Essen, Germany. mark.goepel@uni-essen.de

BACKGROUND: We wanted to test whether phytotherapeutic agents used in the treatment of lower urinary tract symptoms have alpha1-adrenoceptor antagonistic properties in vitro. METHODS: Preparations of beta-sitosterol and extracts of stinging nettle, medicinal pumpkin, and saw palmetto were obtained from several pharmaceutical companies. They were tested for their ability to inhibit [3H]tamsulosin binding to human prostatic alpha1-adrenoceptors and [3H]prazosin binding to cloned human alpha1A- and alpha1B-adrenoceptors. Inhibition of phenylephrine-stimulated [3H]inositol phosphate formation by cloned receptors was also investigated. RESULTS: Up to the highest concentration which could be tested, preparations of beta-sitosterol, stinging nettle, and medicinal pumpkin were without consistent inhibitory effect in all assays. In contrast, all tested saw palmetto extracts inhibited radioligand binding to human alpha1-adrenoceptors and agonist-induced [3H]inositol phosphate formation. Saturation binding experiments in the presence of a single saw palmetto extract concentration indicated a noncompetitive antagonism. The relationship between active concentrations in vitro and recommended therapeutic doses for the saw palmetto extracts was slightly lower than that for several chemically defined alpha1-adrenoceptor antagonists. CONCLUSIONS: Saw palmetto extracts have alpha1-adrenoceptor-inhibitory properties. If bioavailability and other pharmacokinetic properties of these ingredients are similar to those of the chemically defined alpha1-adrenoceptor antagonists, alpha1-adrenoceptor antagonism might be involved in the therapeutic effects of these extracts in patients with lower urinary tract symptoms suggestive of benign prostatic obstruction.

PMID: 10068345 [PubMed - indexed for MEDLINE]


#2

Muscarinic and alpha 1-adrenergic receptor binding characteristics of saw palmetto extract in rat lower urinary tract

Urology. 2007 Jun;69(6):1216-20

OBJECTIVES:
To elucidate the in vitro and ex vivo effects of saw palmetto extract (SPE) on autonomic receptors in the rat lower urinary tract.

METHODS:
The in vitro binding affinities for alpha 1-adrenergic, muscarinic, and purinergic receptors in the rat prostate and bladder were measured by radioligand binding assays. Rats received vehicle or SPE (0.6 to 60 mg/kg/day) orally for 4 weeks, and alpha 1-adrenergic and muscarinic receptor binding in tissues of these rats were measured.

RESULTS:
Saw palmetto extract inhibited specific binding of [3H]prazosin and [N-methyl-3H]scopolamine methyl chloride (NMS) but not alpha, beta-methylene adenosine triphosphate [2,8-(3)H]tetrasodium salt in the rat prostate and bladder.

The binding activity of SPE for muscarinic receptors was four times greater than that for alpha 1-adrenergic receptors. Scatchard analysis revealed that SPE significantly reduced the maximal number of binding sites (Bmax) for each radioligand in the prostate and bladder under in vitro condition.

Repeated oral administration of SPE to rats brought about significant alteration in Bmax for prostatic [3H]prazosin binding and for bladder [3H]NMS binding. Such alteration by SPE was selective to the receptors in the lower urinary tract.

CONCLUSIONS:
Saw palmetto extract exerts significant binding activity on autonomic receptors in the lower urinary tract under in vitro and in vivo conditions.


#3

» Muscarinic and alpha 1-adrenergic receptor binding characteristics of
» saw palmetto extract in rat lower urinary tract

»
» Urology. 2007 Jun;69(6):1216-20
»
» OBJECTIVES:
» To elucidate the in vitro and ex vivo effects of saw palmetto extract
» (SPE) on autonomic receptors in the rat lower urinary tract.
»
» METHODS:
» The in vitro binding affinities for alpha 1-adrenergic, muscarinic, and
» purinergic receptors in the rat prostate and bladder were measured by
» radioligand binding assays. Rats received vehicle or SPE (0.6 to 60
» mg/kg/day) orally for 4 weeks, and alpha 1-adrenergic and muscarinic
» receptor binding in tissues of these rats were measured.
»
» RESULTS:
» Saw palmetto extract inhibited specific binding of [3H]prazosin and
» [N-methyl-3H]scopolamine methyl chloride (NMS) but not alpha,
» beta-methylene adenosine triphosphate [2,8-(3)H]tetrasodium salt in the rat
» prostate and bladder.
»
» The binding activity of SPE for muscarinic receptors was four times
» greater than that for alpha 1-adrenergic receptors. Scatchard analysis
» revealed that SPE significantly reduced the maximal number of binding sites
» (Bmax) for each radioligand in the prostate and bladder under in vitro
» condition.
»
» Repeated oral administration of SPE to rats brought about significant
» alteration in Bmax for prostatic [3H]prazosin binding and for bladder
» [3H]NMS binding. Such alteration by SPE was selective to the receptors in
» the lower urinary tract.
»
» CONCLUSIONS:
» Saw palmetto extract exerts significant binding activity on autonomic
» receptors in the lower urinary tract under in vitro and in vivo conditions.

HS Admin, can you at least focus on experiements that were done in humans? By now we all know that experiments done in mice mean nothing. It has to be human trials that count.


#4

» » Muscarinic and alpha 1-adrenergic receptor binding characteristics of
» » saw palmetto extract in rat lower urinary tract

» »
» » Urology. 2007 Jun;69(6):1216-20
» »
» » OBJECTIVES:
» » To elucidate the in vitro and ex vivo effects of saw palmetto extract
» » (SPE) on autonomic receptors in the rat lower urinary tract.
» »
» » METHODS:
» » The in vitro binding affinities for alpha 1-adrenergic, muscarinic, and
» » purinergic receptors in the rat prostate and bladder were measured by
» » radioligand binding assays. Rats received vehicle or SPE (0.6 to 60
» » mg/kg/day) orally for 4 weeks, and alpha 1-adrenergic and muscarinic
» » receptor binding in tissues of these rats were measured.
» »
» » RESULTS:
» » Saw palmetto extract inhibited specific binding of [3H]prazosin and
» » [N-methyl-3H]scopolamine methyl chloride (NMS) but not alpha,
» » beta-methylene adenosine triphosphate [2,8-(3)H]tetrasodium salt in the
» rat
» » prostate and bladder.
» »
» » The binding activity of SPE for muscarinic receptors was four times
» » greater than that for alpha 1-adrenergic receptors. Scatchard analysis
» » revealed that SPE significantly reduced the maximal number of binding
» sites
» » (Bmax) for each radioligand in the prostate and bladder under in vitro
» » condition.
» »
» » Repeated oral administration of SPE to rats brought about significant
» » alteration in Bmax for prostatic [3H]prazosin binding and for bladder
» » [3H]NMS binding. Such alteration by SPE was selective to the receptors
» in
» » the lower urinary tract.
» »
» » CONCLUSIONS:
» » Saw palmetto extract exerts significant binding activity on autonomic
» » receptors in the lower urinary tract under in vitro and in vivo
» conditions.
»
» HS Admin, can you at least focus on experiements that were done in humans?
» By now we all know that experiments done in mice mean nothing. It has to
» be human trials that count.

Hairsite admin means well ,

poor mice though, being forced to take saw palmetto,


#5

» CONCLUSIONS: Saw palmetto extracts have alpha1-adrenoceptor-inhibitory
» properties.
If bioavailability and other pharmacokinetic properties of
» these ingredients are similar to those of the chemically defined
» alpha1-adrenoceptor antagonists, alpha1-adrenoceptor antagonism might be
» involved in the therapeutic effects of these extracts in patients with
» lower urinary tract symptoms suggestive of benign prostatic obstruction.

Does saw palmetto give same sides as propecia? I’m thinking of starting 320mg SP but not sure about the sideeffects.


#6

A very recent study —

A detailed safety assessment of a saw palmetto extract

Complement Ther Med. 2008 Jun;16(3):147-154

BACKGROUND:
Saw palmetto is commonly used by men for lower-urinary tract symptoms. Despite its widespread use, very little is known about the potential toxicity of this dietary supplement.

METHODS:
The Saw palmetto for Treatment of Enlarged Prostates (STEP) study was a randomized clinical trial performed among 225 men with moderate-to-severe symptoms of benign prostatic hyperplasia, comparing a standardized extract of the saw palmetto berry (160mg twice daily) with a placebo over a 1-year period. As part of this study, detailed data were collected on serious and non-serious adverse events, sexual functioning, and laboratory tests of blood and urine. Between-group differences were assessed with mixed-effects regression models.

RESULTS:
There were no significant differences observed between the saw palmetto and placebo-allocated participants in the risk of suffering at least one serious adverse event (5.4% vs. 9.7%, respectively; p=0.31) or non-serious symptomatic adverse event (34.8% vs. 30.1%, p=0.48). There were few significant between-group differences in sexual functioning or for most laboratory analyses, with only small differences observed in changes over time in total bilirubin (p=0.001), potassium (p=0.03), and the incidence of glycosuria (0% in the saw palmetto group vs. 3.7% in the placebo group, p=0.05).

CONCLUSIONS:
Despite careful assessment, no evidence for serious toxicity of saw palmetto was observed in this clinical trial. Given the sample size and length of this study, however, these data do not rule out potential rare adverse effects associated with the use of saw palmetto.


#7

» » CONCLUSIONS: Saw palmetto extracts have
» alpha1-adrenoceptor-inhibitory
» » properties.
If bioavailability and other pharmacokinetic properties
» of
» » these ingredients are similar to those of the chemically defined
» » alpha1-adrenoceptor antagonists, alpha1-adrenoceptor antagonism might
» be
» » involved in the therapeutic effects of these extracts in patients with
» » lower urinary tract symptoms suggestive of benign prostatic
» obstruction.
»
» Does saw palmetto give same sides as propecia? I’m thinking of starting
» 320mg SP but not sure about the sideeffects.

no it does not,
prop actually decreases serum blood levels of DHT , while Saw Palmetto has been shown to not affect these levels

this may be why prop has all the nasty side effects


#8

» no it does not,
» prop actually decreases serum blood levels of DHT , while Saw Palmetto has
» been shown to not affect these levels
»
» this may be why prop has all the nasty side effects

it won’t have any sideeffects if it only binds to scalp receptors but how does it differentiate between scalp receoptors and others?


#9

» » no it does not,
» » prop actually decreases serum blood levels of DHT , while Saw Palmetto
» has
» » been shown to not affect these levels
» »
» » this may be why prop has all the nasty side effects
»
» it won’t have any sideeffects if it only binds to scalp receptors but how
» does it differentiate between scalp receoptors and others?

somehow it interferes with the binding process of DHT to both the androgen receptors at the base of hair follicles…as well as androgen receptors on the prostate gland