Taurine Enhances the Sexual Response and Mating Ability in Aged Male Rats - Advances in Experimental Medicine and Biology - page 327

in the corpora cavernosa (Mills et al. 1996 ; Lugg et al. 1995 ) . As mentioned above,
we found that taurine could increase the levels of testosterone and NO in aged rats.
In addition, a number of studies have reported that the level of taurine is decreased
in aged animals (Wallace and Dawson 1990 ; Dawson and Wallace 1992 ) . However,
the correlation between taurine deficiency and sexual function decline in the male
aged rats is still unknown. The primary aim of the present study was to investigate
the effect of taurine on sexuality and mating ability in aged male rats.

32.2 Methods

32.2.1 Experimental Animals and Treatments

Twenty-four aged male Wistar rats (20 months) were obtained from Kunming
Institute of Zoology, Chinese Academic Sinica. The rats were randomly divided into
three groups, eight in each. Rats in control group (Con) were given tap water, and rats
in the other two groups were given water containing 1% taurine (taurine group, Tau)
and 1% b -alanine ( b-alanine group, b-Ala). They were maintained in controlled light
(14-h light, 10-h dark) and temperature (22 ± 2°C), and were given free access to rat
chow and water. The study protocol was approved by our Ethical Committee and
conducted in compliance to the Helsinki Declaration.

32.2.2 Sexual Response and Mating Ability Examining

The sexual response was determined on the 60th day after taurine administration
according to the reported method by means of apomorphine (Sachs et al. 1994 ) . The
erection latency (EL) and erection frequency (ERF) were recorded. Mating ability
was examined on the 74th day in accordance with the previous method (Lumley and
Hull 1999 ). Mount latency (ML), mount frequency (MF), intromission frequency
(IF), and ejaculation frequency (EJF) were measured.

32.2.3 Sample Collection and Biochemical Analysis

Rats were killed after being treated for 110 days, and blood and penis were
collected. Blood was used for gonadotropin-releasing hormone (GnRH), LH,
follicle-stimulating hormone (FSH), and T and estradiol (E2) analysis. Penis was
homogenated in cold physiological saline, and then was used for total protein (TP),
NOS, and NO analysis. All the indicators were analyzed according to the intro-
duction of reagent kits (Beijing Chemclin Biotech Co., Ltd., China).