Effects of γ-Aminobutyric Acid on the Erectogenic Properties of Sildenafil

Adefegha S. A., Oyeleye S. I., Oboh G.


Erectile dysfunction (ED) is a disorder of increasing socio-economic burden. Therapeutic drugs such as sildenafil have
been in use for the treatment of ED, but with their associated side effects. γ-aminobutyric acid (GABA) is a
neurotransmitter with possible vasodilatory properties. In this study, the effect of GABA on the erectogenic properties of
sildenafil was investigated. Aqueous solution of GABA and sildenafil (1 mM) was separately prepared as well as the
mixtures of both (75% GABA + 25% sildenafil; 50% GABA + 50% sildenafil; 25% GABA + 75% sildenafil).
Thereafter, the in vitro effects of all the studied samples on the activities of arginase, angiotensin-I converting enzyme
(ACE) and acetylcholinesterase (AChE) were investigated. The results revealed that all the samples inhibited arginase,
ACE and AChE activities. Considering the various combinations, 25% GABA + 75% sildenafil had the highest arginase
inhibitory effect, 50% GABA + 50% sildenafil showed the highest ACE inhibiting effect, while 25% GABA + 75%
sildenafil exhibited the highest AChE inhibitory effect. Therefore, the observed enzyme inhibiting effect of sildenafil,
GABA and their various combinations on rat penile arginase, ACE and AChE activities could be part of the mechanism
by which they elicit their erectogenic properties. The various combinations could thus serve as therapeutic intervention
for the management of ED with a possible reduction in the side effects associated with the use of sildenafil; nevertheless,
the combination of 75% GABA with 25% sildenafil exhibited the highest erectogenic potential.


Erectile dysfunction; γ-aminobutyric acid; sildenafil; arginase; ACE, AChE.

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DOI: https://doi.org/10.25258/ijtpr.v9i03.9077


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