BioMed Research International

BioMed Research International / 2016 / Article

Research Article | Open Access

Volume 2016 |Article ID 9706429 | 10 pages | https://doi.org/10.1155/2016/9706429

Effects of the Aqueous Extract of Eremomastax speciosa (Acanthaceae) on Sexual Behavior in Normal Male Rats

Academic Editor: Kota V. Ramana
Received18 Mar 2016
Revised12 May 2016
Accepted17 May 2016
Published20 Jul 2016

Abstract

Objective. We studied prosexual effects of Eremomastax speciosa aqueous extract in male adult rats. Materials and Methods. 100 and 500 mg/kg of extract were administered orally (days 0, 1, 4, 7, 14, and 28 (posttreatment)). The sexual behavior of rats receiving a single dose (500 mg/kg) was also evaluated after pretreatment with Lω-NAME (10 mg/kg), haloperidol (1 mg/kg), or atropine (5 mg/kg). Controls received distilled water or testosterone enanthate (20 mg/kg/day/3 days (s.c.) before the test). Results. The extract (days 1–14) had no significant effect on mount, intromission, and ejaculation frequencies but on day 28 (14 days after treatment), it increased frequency of mounts and intromissions at 500 mg/kg. Mount, intromission, and ejaculation latencies reduced and postejaculatory intervals decreased but the effect did not persist 2 weeks after treatment. Extract prosex effects were greatly reduced by atropine and completely abolished by haloperidol, while Lω-NAME increased mount latency and potentiated extract effect on intromission and ejaculation latencies. Conclusion. In summary, E. speciosa extract can have positive effects on male sexual motivation and performance when administered for two weeks at the dose of 500 mg/kg. The effects (dopaminergic and/or cholinergic dependent) tend to appear during the posttreatment period.

1. Introduction

The male reproductive capacity is deficient in more than 50% of infertile couples. The causes of this decline in male reproductive capacity are numerous. Sexual disorders are among the most abundant; in addition, we can mention erectile dysfunction. Erectile dysfunction is sometimes called impotence; this clinical term is retained to describe the inability to achieve and maintain penile erection sufficiently rigid to permit satisfactory sexual intercourse [1]. On the organic origin, psychogenic, erectile dysfunction is widespread and affects men of all ages (mainly 40–70 years), all occupational groups, and all sociocultural levels [2]. Diabetes, hypertension, alcoholism, smoking, and prostatic diseases are the risk factors of this sexual disorder [3]. About 150 million people worldwide suffer from erectile dysfunction [4]. This problem is also likely to seriously hamper relations within a couple sometimes leading to divorce. Because of the multifactorial etiology and investigation methods increasingly sophisticated regimens of erectile dysfunction are more and different depending on the standard of living. In developed countries, the therapy involves the implantation of penile prostheses, intracavernous injections, and the use of certain pharmaceutical products (phosphodiesterase type V inhibitors) [5]. These pharmaceuticals also favor the persistence of smooth muscle relaxation and therefore the maintenance of erection [6]. In developing countries, by cons because of the influence of the economic crisis, modern health infrastructure, high cost of drugs, and respect for customs, about 80% of the population use medicinal plants for treatment. Many plants (Montanoa tomentosa, Syzygium aromaticum, Massularia acuminata, and Fadogia agrestis) have the reputation of being an aphrodisiac. The aphrodisiac activity of these plants is attributed to the presence of one or more phytoconstituents such as sterols, phenols, alkaloids, amino acid, and saponin responsible for improving sexual function through the regulation of neurotransmitters and relaxation smooth muscle of the corpora cavernosa [7, 8]. This is the case of E. speciosa, widely distributed in tropical Africa [9]. The plant is a robust, polymorphous shrub growing to a height of 2 m. The stem is quadrangular, and the leaves are purple on the underside. Several constituents already have been approved, such as flavonoids, alkaloids, triterpenoids, and sterol [10]. E. speciosa is cited for its various beneficial effects, which include stomach complaints, dysentery, hemorrhoids, urinary tract infection, painful menstruation, diarrhea, and male and female infertility [1118] and is commonly referred to as “blood plant” since it is also widely used to treat cases of anemia. In addition to this investigation, little or no information on copulatory activity is available. The present study was designed to study the aphrodisiac activity of aqueous extract of E. speciosa in male rat.

2. Material and Methods

2.1. Plant Material

The fresh leaves of Eremomastax speciosa (Hochst.) Cufod. (Acanthaceae) were harvested between the months of August-September 2014 in Yaoundé, Cameroon political capital, specifically in common Emana and Messassi. A sample of this plant was authenticated by Paul Mezili. A specimen of this plant is kept in the National Herbarium of Cameroon, IRAD, Yaoundé, under the number HNC/136984.

2.2. Preparation of Water Extract

Eremomastax speciosa aerial parts were cut into pieces and dried outdoors in the shade at room temperature and then ground using a blender to obtain a powder. Using a spatula, 560 g of this powder was mixed in 5.6 liters of boiled water for 15 minutes. The extract solution was filtered with a filter paper (Whatman number 3). The filtrate obtained was finally dried in an oven at ventilation at 40°C. This yielded 56.20 g of dry extract, which corresponds to a yield of 10.03%.

2.3. Animal Material

Older adult male rats (Rattus norvegicus) of 3.5–4 months, weighing between 200 and 230 g, were used for the experiments on copulatory activity. These animals (males and females) were from the animal facility of the Faculty of Sciences of the University of Yaounde I, Cameroon. They were raised in rooms at room temperature. In these premises, the photoperiod was 12 hours and humidity 50%. The animals had ad libitum access to water and food (66.87% corn flour, 30.85% fish meal, 1.03% shell powder, 1.03% of salt, 0.11% peanut oil, and 0.11% of multivitamin). The ethics committee of the Cameroon Ministry of Scientific Research and Innovation (MINRESI) approved all experimental procedures.

2.4. Animal Grouping and Extract Administration

24 rats gonado-intact and sexually experienced were randomly assigned to one of the following groups: group 1 receiving distilled water (1 mL/kg) and serving as a neutral control group, group 2 or standard group treated by a subcutaneous injection of testosterone enanthate (20 mg/kg/day) for 3 days before the start of copulatory tests [19], and groups 3 and 4, respectively, treated by the aqueous extract of E. speciosa at doses of 100 and 500 mg/kg. In rats, distilled water and the extract were orally administered once a day between 20 h and 20 h 30 local time and for a period of 14 days. On days 0, 1, 4, 7, and 14 of treatment and day 28 (posttreatment), the sexual behavior of animals was analyzed in a quiet enclosure for one hour.

In a complementary study, the impact of a dose of 500 mg/kg extract of E. speciosa on dopaminergic, cholinergic, and nitergic systems was studied. 30 gonado-intact rats were used in this study and divided into 6 groups of 5 animals each. Prior to administration of the extract of E. speciosa (500 mg/kg), the rats received, as appropriate, intramuscular injection of atropine (5 mg/kg) (CC Pharma, Belgium) or haloperidol (1 mg/kg) (Janssen-Cilag, France) or an intraperitoneal injection of Lω-NAME (10 mg/kg) (Sigma, USA) 1 h before the coupling test. The doses of these substances were chosen based on preliminary work. Control animals were treated with diluents solvent (5 mL/kg of Tween 80; 0.25% in 0.9% NaCl) intraperitoneally or intramuscularly.

2.5. Male Rat Sexual Behavior: Test Procedure

After 30 minutes of acclimatization of each male in copulation cage, an ovariectomized female [20] made receptive by subcutaneous and sequential injections of 30 micrograms of estradiol benzoate (Sigma, USA) and 500-microgram progesterone (Bayer Pharma AG, Germany) 48 pm and 6 am, respectively, before the start of the test, was introduced in the cage. The following copulatory parameters were recorded for 1 h with reference to standard methods [2123]: mounted frequency (FM) or the total number of mounts during the observation period; frequency interferences (FI) or the total number of interferences during the hour of study; frequency of ejaculations (FE) which is the total number of ejaculations; mount latency (ML) and intromission latency (IL) which are the time from intromission of a female in the cage and the first intromission and mounts, respectively; ejaculation latency which is the time between the first ejaculation and the first intromission; postejaculatory interval which is the time between the first ejaculation and the new intromission. Some additional male sexual behavior parameters computed include % mounted = (number mounted/number paired) × 100; % intromitted = (number of rats that intromitted/number paired) × 100; % index of libido = (number mated/number paired) × 100; % ejaculation = (number of rats that ejaculated/number paired) × 100; copulatory efficiency = (IF divided by MF + IF) × 100; inter-copulatory efficiency = average time between intromissions (calculated as ejaculated latency divided by intromission frequency).

2.6. Statistical Analysis

The statistical analysis was performed using the GraphPad Prism software. The Student test Newman Keul was selected for the comparison of averages. The difference between two is said to be significant if .

3. Results

3.1. Prosexual Effects of E. speciosa Aqueous Extract on Some Parameters of Performance and Sexual Motivation in Gonad-Intact Male Rats

Treatment with the aqueous extract of E. speciosa (days 1–14) had no statistically significant effect on the frequencies of mounts, intromissions, and ejaculations compared with animals treated with distilled water. However, on day 28 (14 days posttreatment), there were significant increases in the frequency of mounts and of intromissions at the 500 mg/kg dose of extract compared with significant distilled water controls () and the positive controls () (Tables 1 and 2). Ejaculation frequencies remained unchanged up to day 14 of extract treatment and increased to and on day 28 compared with day 0 observations ( and ) (Table 3). On day 7, there were significant decreases in the mount latency, intromission latency, and ejaculation latency in rats receiving the extract at doses of 100 and 500 mg/kg () compared with day 0 and neutral control values (Tables 4, 5, and 6). On day 28 (posttreatment) mount latency decreased in rats given the extract and testosterone compared with day 0. Postejaculatory intervals decreased only for the 100 mg/kg dose on day 14 of treatment compared with days 0–7 but the effect did not persist 2 weeks after cessation of treatment (Table 7). The computed male sexual behavior parameters including percentages of intromissions and ejaculations and index of libido were higher in the extract-treated animals compared with the distilled water controls. In contrast, the extract reduced intercopulatory efficiency of the treated animals compared with the control animals. Copulatory efficiency decreased in rats receiving the extract at the dose of 100 mg/kg compared with the neutral controls (Table 8).


TreatmentDay of observation
D0D1D4D7D14D28

H2O (1 mg/kg)
Testosterone (20 mg/kg)
Extract (100 mg/kg)
Extract (500 mg/kg)

Values are expressed as mean ± SEM (). In the same column, ; versus negative control and versus testosterone control (frequency = number).

TreatmentDay of observation
D0D1D4D7D14D28

H2O (1 mg/kg bw)
Testosterone (20 mg/kg)
Extract (100 mg/kg)
Extract (500 mg/kg)

Values are expressed as mean ± SEM (). In the same column, versus negative control and versus testosterone control (frequency = number).

TreatmentDay of observation
D0D1D4D7D14D28

H2O (1 mg/kg)
Testosterone (20 mg/kg)
Extract (100 mg/kg)
Extract (500 mg/kg)

Values are expressed as mean ± SEM (). Frequency = number.

TreatmentDay of observation
D0D1D4D7D14D28

H2O (1 mg/kg)
Testosterone (20 mg/kg bw)
Extract (100 mg/kg)
Extract (500 mg/kg)

Values are expressed as mean ± SEM (). ML (seconds); different superscript letters in the same row refer to a significant difference; in the same column, ; versus neutral control and ; ; versus testosterone control.

TreatmentDay of observation
D0D1D4D7D14D28

H2O (1 mg/kg)
Testosterone (20 mg/kg bw)
Extract (100 mg/kg)
Extract (500 mg/kg)

Values are expressed as mean ± SEM (). IL (seconds); different superscript letters in the same row refer to a significant difference; in the same column, versus neutral control.

TreatmentDay of observation
D0D1D4D7D14D28

H2O (1 mg/kg)
Testosterone (20 mg/kg)
Extract (100 mg/kg)
Extract (500 mg/kg)

Values are expressed as mean ± SEM (). EL (seconds); different superscript letters in the same row refer to a significant difference; in the same column, ; ; versus neutral control and ; versus testosterone control.

TreatmentDay of observation
D0D1D4D7D14D28

H2O (1 mg/kg bw)
Testosterone (20 mg/kg)
Extract (100 mg/kg)