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- Complementary Medicine -

Effects of Boesenbergia rotunda (L.) Mansf. on sexual behaviour of male rats

Paiwan Sudwan^1,2, Kanokporn Saenphet¹, Salika Aritajat¹, Narit Sitasuwan¹

¹Department of Biology, Faculty of Science, ²Department of Anatomy, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand

Abstract

Aim: To study the effects of Boesenbergia rotunda (Krachai) on sexual behaviour in male albino rats. Methods: Thirty-two male Wistar rats were equally divided into four groups: experimental groups were gavaged with the ethanolic extract of the rhizome of B. rotunda at doses of 60, 120 and 240 mg/kg and a control group received distilled water, for 60 days. Sexual behaviour, reproductive organs, diameter of seminiferous tubule, epididymal sperm density, and androgenic hormones were evaluated. Results: Within 30-min observation, there was no significant difference of courtship behaviour, mount frequency (MF), intromission frequency (IF), mount latency (ML), intromission latency (IL), copulatory efficiency or intercopulatory interval in male rats. In three 10-min intervals over a 30-min period, courtship behaviour and MF during the first 10-min were significantly higher than those in the second and third 10-min observation in all groups, whereas IF had no significant difference. All doses of B. rotunda extract significantly increased the relative testicular weight and the diameter of the seminiferous tubules. The dose of 60 mg/kg also significantly increased the relative weight of the seminal vesicle. Nevertheless, the sperm density, serum testosterone and androstenedione levels were not affected by the B. rotunda extract. Conclusion: B. rotunda does not affect sexual behaviour nor serum androgenic levels. (Asian J Androl 2007 Nov; 9: 849_855)

Keywords: Boesenbergia rotunda; sexual behaviour; testosterone; androstenedione; reproductive organ; sperm density

Correspondence to: Dr Paiwan Sudwan, Department of Anatomy, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand.
Tel: +66-53-945-312 ext. 208, +66-081-366-1526
Fax: +66-53-945-304
E-mail: pasudwan@mail.med.cmu.ac.th
Received 2006-06-22 Accepted 2006-11-08

DOI: 10.1111/j.1745-7262.2007.00255.x

1 Introduction

Boesenbergia rotunda (L.) Mansf., called "Krachai" in Thai, is a herb of the Zingiberaceae family. The fresh rhizomes are commonly used in Southeast and South Asia as a food ingredient. In Thailand, they are also used as a folk medicine for health-promotion, antiflatulence, stomach discomfort, diuresis, leucorrhea, treatment of oral diseases and antidysentery [1] without acute toxi-city [2]. The rhizomes of B. rotunda were found to contain 1,5-Cineol, Boesenbergin A, dl-Pinostrobin Corphor, flavonoid, Chromene [1], panduratin C, panduratin A, hydroxypanduratin A, helichrysetin, 2',4',6'-trihydroxyhydrochalcone and uvangoletin [3]. In addition to the purposes of primary health care, the rhizomes have been reported as having aphrodisiac properties [4_7]. It is sometimes referred to as "Thai ginseng" [4] and has long been used among Thai men for sexual enhancement by using it as an ingredient of traditional remedies for impotency [5] and a sexual enhancing herb [4_8]. Nevertheless, there is no animal model to confirm or support these properties.

In the present study, we investigated the effect of ethanolic extract from the rhizomes of B. rotunda on sexual behaviour, reproductive organs, diameter of seminiferous tubule, sperm density and sex hormones in male albino rats to evaluate its properties.

2 Materials and methods

2.1 Animals

Thirty-two male and 20 female Wistar rats (Rattus norvegicus), weighing 200_240 g and 6 weeks of age were purchased from the National Laboratory Animal Centre, Salaya, Nakhorn Pathom, Thailand. The animals were housed in groups (two rats per cage) under standard conditions (inverted 12 h : 12 h light : dark cycle) at 25 ± 2ºC and with free access to pelleted food and water at the Animal Facility Unit, Department of Biology, the Faculty of Science, Chiang Mai University. They were accustomed to the housing conditions for at least 1 week before studying. All experimental procedures were in accordance with institutional regulations for Animal Care and Use (No. RE 001/06), Department of Biology, Faculty of Science, Chiang Mai University.

2.2 Plants and extract preparation

The rhizomes of B. rotunda were collected from Chiang Mai Province, Thailand and identified by Dr Charun Maknoi, the Botany Section, Queen Sirikit Botanic Garden, Ministry of Natural Resources and Environment, Mae Rim, Chiang Mai, Thailand (voucher specimen No. 06-051718). They were sliced, dried in an oven at 60ºC, ground, extracted with 50% ethanol in a soxhlet apparatus and evaporated by rotary evaporation. This extract was stored at 4ºC till use. All doses of B. rotunda extract were diluted in distilled water at a low dosage (60 mg/kg BW), at the amount equivalent to the quantity of daily traditional use in humans (120 mg/kg BW) and at a high dose (240 mg/kg BW). The amount of 120 mg/kg BW was used by referring to Hem-hongsa and Chaophya Abhaibhubejhr Hospital (Muang, Prachinburi, Thailand) [1, 9].

2.3 Experimental design

The animals were divided into three groups (n = 8) of male rats that were given the B. rotunda extract at doses of 60, 120 and 240 mg/kg BW by oral administration for 60 days and a control group (n = 8), which received distilled water at 1 mL/day. Sexual behaviours were tested twice in each of the 32 male rats between days 26_30 and between days 56_60 of the B. rotunda application by introducing a receptive female with estrous phase into the observation cage. At day 61, the animals were anesthetized and blood was collected for hormone assay by cardiac puncture from the left ventricle. The testis, cauda epididymis, seminal vesicle and prostate gland were removed, trimmed of fat, and weighed. After weights were recorded, the cauda epididymis was cut into small pieces, homogenized in 10 mL of 0.9% NaCl and the sperm number was estimated in duplicate using a hemocytometer (Improved Neubauer, Boeco, Germany).

2.4 Measurement of seminiferous tubule diameter

The left testis from each animal was fixed in Bouin's solution for paraffin work and sectioned at 6 μm, stained with hematoxylin and eosin (H&E) and periodic acid-Schiff (PAS), and examined with a light microscope. Approximately 20 (per testis) cross-sections of seminiferous tubules with an apparent lumen were sampled. The diameter of round tubules or the short axis of elliptical tubules was measured using an ocular micrometer coupled to a 40 × objective lens.

2.5 Sexual behaviour testing procedure

The totals of 32 male rats were individually tested for sexual behaviour in a rectangular glass observatory cage and were given a 10-min accommodation for adaptation period. Thereafter, an estrous female was introduced and sexual behaviour was recorded along 30 min. Video recordings were made throughout the whole period for following behavioural parameters: courtship behaviour, sniffing, rubbing against or moving under or over the female's torsal [10]; mount frequency (MF), the number of mounts; intromission frequency (IF), the number of intromissions; mount latency (ML), time from introduction of the female to the first mount with pelvic thrusting; intromission latency (IL), time from introduction of the female to the first mount with pelvic thrusting and vaginal penetration (intromission) [11]. Courtship behaviour and latencies were recorded in seconds.

The following parameters were calculated: % courtship behaviour, % mount, % intromission, copulatory efficiency (number of intromissions/number of mounts) and intercopulatory interval (average time between intromissions) [12].

2.6 Hormone tests

Serum was prepared for the electrochemiluminescence immunoassay (ECLIA) and the radioimmunoassay (RIA). The testosterone levels were determined by using Elecsys Testosterone reagent kit (Roche Diagnostics GmbH, Indianapolis, IN, USA) for the Elecsys 2010 immunoassay analyzer and androstenedione was determined by using a Coat-A-Count Direct Androstenedione kit (Diagnostic Products Corporation, Los Angeles, CA, USA) for Gamma counter with the cooperation of the Reproductive Medicine Laboratory, Department of Obstetrics and Gynecology, Faculty of Medicine, Chiang Mai University.

2.7 Data analysis

Data were expressed in mean ± SD. The mean values of sexual behaviour for both doses and durations were statistically analyzed by two-way analysis of variance (ANOVA) layout completely randomized design, followed by one-way ANOVA and subsequently least significant difference (LSD) multiple comparisons test. Mean values of other parameters were statistically analyzed by one-way ANOVA followed by LSD. The percentages were analyzed using Chi-squared test. The SPSS 6.0 and 10.0 (SPSS Inc., Chicago, IL, USA) was employed for all statistical analyses. Significance was inferred when P ≤ 0.05.

3 Results

3.1 Sexual behaviour

There were no significant changes in the whole 30-min period of % courtship behaviour, % mounting, % intromission, the time of courtship behaviour, IF, ML, IL, copulatory efficiency and intercopulatory interval in male rats (Tables 1, 2). However, the study of three 10-min intervals over a 30-min period revealed that the control and treated groups of rats had significantly higher courtship behaviour and MF during the first 10-min observation than in the second and third 10-min observation (Tables 3, 4), whereas both treated and control groups had no significant difference in three 10-min periods of IF during 30 min and they showed consistent frequency along 30 min (Table 5).

3.2 Organ weights

All groups of male rats receiving B. rotunda extract had significantly higher relative testis weight than the control group. B. rotunda extract at the dose of 60 mg/kg BW also significantly induced the relative weights of the seminal vesicles of the male rats (Figure 1). There were no significant differences in the caudal epididymis or prostate gland weights when compared with the control group.

3.3 Diameter of seminiferous tubule

For all groups of male rats receiving B. rotunda extract, the diameters of seminiferous tubule were larger than that the control group (Figure 2).

3.4 Sperm density

All doses of the ethanolic extract of B. rotunda did not significantly affect the sperm density when compared with the control (Figure 3).

3.5 Hormone levels

Serum testosterone and androstenedione levels were not affected by B. rotunda extract (Figure 4).

4 Discussion

This study used different doses and durations of B. rotunda extract to determine their effects on sexual behaviour in male rats. The results showed clearly that B. rotunda extract in all doses and durations did not affect sexual behaviour when compared with the control groups. Consequently, this research did not support the belief that B. rotunda could enhance sexual behaviour.

Nevertheless, B. rotunda extract caused an increase in the testicular weight and seminiferous tubular diameter of all treated groups and in the seminal vesicle weight of the lowest treated group. These weight gains may signify a selective effect of B. rotunda as reported in Lepidium meyenii [13]. Because B. rotunda extract did not change the weights of the other sexual organs, sperm density, serum testosterone or androstenedione levels after being treated for 60 days, it is difficult to conclude that ethanolic extract from B. rotunda could enhance sexual activity. This plant may have an opportunity to make itself fully apparent in other conditions as reported in the experiments with other plant species in various doses and times [14, 15], in various solvent extractions or with methods of extraction [16], or in sexual condition of male rats [11, 16_17]. Likewise, Watcho et al. [14, 15] found that the rats treated with Mondia whitei for 55 days and 1, 2, 4 and 6 h after treatments showed no changes in testosterone concentration, but an application of M. whitei for 8 days induced an increase in the testicular weight, testicular testosterone level and sperm density without affecting the accessory gland weights [15]. Another study in aphrodisiac herbs, Tribulus terrestris extract did not affect the sexual behaviours or intracavernous pressure in normal rats, but it improved those parameters in the castrated rats [17]. The study of T. terrestris was followed in humans and showed a lack of effect on testosterone and androstenedione levels in young men receiving the extract at 1, 3, 8, 20 and 24 days from the beginning of the supplementation [18]. Thus, B. rotunda will be needed to demonstrate the course and dose response relationship, animal conditions or ultrastructural changes of testis.

In conclusion, the ethanolic extract of B. rotunda, does not affect sexual behaviour or serum androgen levels, but it enhances seminiferous tubule, testis and seminal vesicle.

Acknowledgment

Thanks to the Scholarship of Commission on Higher Education, Ministry of Education, Faculty of Medicine and the research fund of Faculty of Science, Chiang Mai University, Thailand for financial support. We also would like to thank Mr Supap Saenphet, Mr Suluck Wutteeraphon, Ms Warunya Ittipunkul and Ms Siriporn Nunta, for their kind cooperation and technical assistance and to Ms Lucy Coombs for proofreading the manuscript.

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