Effect of Chlorophytum borivilianum on Fluoxetine Induced Sexual Dysfunction in Female Rats

 

Neeraj Vyawahare, Virendra Kagathara*, Rohini Pujari, Manoj Patil, Imtiyaz Ansari and Amol Bhandare

AISSMS College of Pharmacy, Kennedy Road, Nr. RTO, Pune-411001, Maharashtra, India.

 

ABSTRACT

Treatment with selective serotonin reuptake inhibitors (SSRI’s) has been shown to cause reduced libido in women. A large body of evidence suggests that serotonin may influence sexual behavior in estradiol + progesterone primed, ovariectomized female rats. In the present study, the effect of 2 weeks of fluoxetine administration (10 mg/kg daily) and co administration of fluoxetine (same dose) and hydroalcoholic extract of Chlorophytum borivilianum (CB) (100, 300 and 500 mg/kg daily) on copulatory behavior in hormone primed ovariectomized rats was investigated. Fluoxetine significantly reduced various proceptive and receptive behaviors of female rats as compared to normal rats. In contrast, these behavioral parameters were significantly increased by co administration of various doses of CB with fluoxetine as compared to fluoxetine treated rats. The results point towards the potential role and probable use of CB in females with antidepressant induced reduced libido.

 

KEY WORDS: Chlorophytum borivilianum; fluoxetine; libido; ovariectomized; proceptive; receptive

 

INTRODUCTION

The selective serotonin reuptake inhibitors (SSRIs) have become the most frequently prescribed drugs for the treatment of depression1. Fluoxetine is one among these, prescribed for depression as well as for a variety of other disorders such as premenstrual dysphoria, anxiety and anorexia which are more prevalent in females than in males2. Treatment with SSRIs has been reported to reduce libido in both sexes, to cause anorgasmia in women and to increase ejaculation latency in men. Particularly when the SSRIs are used for prophylactic purposes in patients that have recovered from depression, and when they are used for psychiatric conditions not associated with a reduction in libido (such as panic disorder, obsessive compulsive disorder, and premenstrual dysphoria), sexual dysfunction is probably the most cumbersome of the SSRI-associated side effects3. It has been suggested that onset of disruptions in sexual functioning can occur as early as 7 days after initiation of antidepressant treatment4. Yet, as much as 32% of female patients may experience SSRI-induced sexual dysfunction, the mechanisms responsible for such drug-induced sexual dysfunction in females have been difficult to identify, perhaps due to the complexity of the female reproductive cycle and the number of neural and endocrine loops involved2. Given the fact that all serotonin reuptake inhibitors, despite marked differences in chemical structure, induce similar sexual side effects, it is likely that these effects are, indeed, attributable to inhibition of the serotonin transporter and to a subsequent increase in the synaptic concentrations of serotonin3.

 

Chlorophytum borivilianum San. F. (Liliaceae) is a traditional perennial herbaceous medicinal plant commonly known as safed musli5. Tribals in India have used safed musli since ages for enhancing their virility6. It contains proteins (8-9%), carbohydrates (41%), root fibers (4%), saponins (2- 17%), minerals and vitamins.

Saponin is the chief medicinal compound present in the roots. Saponins and alkaloids present in the plant are the primary source of its significant medicinal properties5.  It is scientifically documented for its antistress7, antimicrobial8, analgesic9, anti-inflammatory10 and immunomodulatory11 activities. Also, it has been traditionally acclaimed and advocated for its aphrodisiac activity12, 13. However its effect on libido in females has not been studied.

 

Intact female rats in the estrous phase—as well as ovariectomized females primed with estradiol and progesterone— respond to male mounting with a characteristic dorsiflexion of the back that can be easily registered, so called lordosis behavior. In addition, the female solicits male sexual activity by distinct presenting postures called proceptivity, such as darting (run of several steps followed by assumption of crouching posture), hopping (a short leap or jump in which female lands on all four paws), and ear wiggling (a distinctive vibrations of ear). Thus, examination of a female rat exposed to a sexually active male can easily assess her sexual receptivity and proceptivity3. Hence the present investigation was carried out to study the effect of hydroalcoholic extract of Chlorophytum borivilianum on fluoxetine induced sexual dysfunction in female rats.

 

MATERIALS AND METHODS:

Plant material:

The hydroalcoholic extract of tubers of Chlorophytum borivilianum was received as a gift sample (SME/8006) from Green Chem., Bangalore, India.

 

Chemicals and drugs:

Fluoxetine (Prodep®) capsule, ketamine injection (Ketamin), sesame oil and propylene glycol were purchased from the local market. Estradiol benzoate AR and Progesterone AR were purchased from the Rajesh Chemicals, Mumbai.

 

Animals:

Healthy male and female wistar rats (150-200g) and male swiss albino mice (18-22 g) were obtained from Yash Farms, Pune and were housed in CPCSEA approved animal house in groups of six in polypropylene cages. They were maintained at 25 ± 2° C and relative humidity of 45 to 55% and under standard environmental conditions (12 hrs light 12 hrs dark cycle). The animals had free access to food (Chakan Oil Mills, Pune, India) and water ad libitum. All the procedures were performed in accordance with the Institutional Ethical Committee constituted as per the directions of the CPCSEA (CPCSEA/IAEC/PC-05/07-2K8).

 

Acute toxicity test:

Acute toxicity study was performed in healthy adult male albino mice (18-22 g) as per guidelines (AOT 425) suggested by the Organization for Economical Co-operation and Development. The mice were observed continuously for 2 hrs for behavioral and autonomic profiles and for any other sign of toxicity or mortality up to a period of seven days.

 

Surgery:

All female rats were ovariectomised (OVX) 30 days prior to testing using standard aseptic surgical techniques and under deep anesthesia, induced by intraperitonial administration of 100 mg/kg ketamine, in a volume of 0.1ml/kg. All females received at least one week of postoperative care prior to initiation of experiment.

 

Induction of behavioral estrus:

For induction of behavioral estrus, OVX female rats were subcutaneously (SC) administered with 25 µg estradiol benzoate (EB; in 0.1 ml sesame oil) 48 h prior to behavioral testing and 500 µg of progesterone (P; in 0.1 ml propylene glycol) 5 h before testing14.

 

Training of male rats for sexual experience:

To make sexually experienced, male rats were given 4 training sessions (twice a week for 2 weeks) with receptive females for the period of 30 min. Only males displaying at least 2 ejaculations during the 4 training test sessions were included in the study. The females used for the sexual training of the male were not used for the further experiment15.

 

Statistical analysis:

The results are expressed as mean ± SEM. Comparison between the groups were made by one way analysis of variance (ANOVA) followed by Dennett’s ‘t’ test.

 

EXPERIMENTAL PROTOCOL:

OVX female rats were divided into 5 groups (n=6) as control, FLX, FLX+CB-100, FLX+CB-300 and FLX+CB-500 group. Rats in first and second group received saline (0.2 ml) and fluoxetine (10 mg/kg, i.p.) dissolved in saline (given volume: 2 ml/kg) respectively, while those in third, fourth and fifth group were treated with same doses of fluoxetine along with 100, 300 and 500 mg/kg of Chlorophytum borivilianum for 14 days. On 14th day, 1h after the respective treatments, all the female rats in behavioral estrus phase were individually paired with single sexually experienced male rat in copulatory arena for the period of 30 min and various female proceptive and receptive behaviors were observed.

 

RESULTS:

Acute oral toxicity test:

All mice were free of any toxicity as per acceptable range given by the OECD guidelines up to the dose of 2000 mg/kg. From this data and pilot study reports; three different doses 100, 300 and 500 mg/kg were selected for this study.

 

Fig 1: Effect of fluoxetine and CB extract on hop, dart, ear wiggling and solicitation. n=6, Comparison between control and FLX treated group was made by Student’s‘t’ test while between FLX and FLX + CB (100, 300 and 500 mg/kg) was made by one way analysis of variance (ANOVA) followed by Dunnett’s’ test. #P<0.05, ##p<0.01 against control and *P<0.05, **P<0.01 against FLX.

 

Effect of fluoxetine on sexual receptivity and proceptivity:

Fluoxetine affected adversely and significantly various receptive and proceptive sexual behaviors. Comparing rats of fluoxetine treated group with control group, it was found that fluoxetine significantly reduced various proceptive behaviors like hops (16.5 ± 0.4282 versus 20.33 ± 1.054 in controls), darts (17 ± 0.6325 versus 19.83 ± 0.7923 in controls), ear wiggling (14.83 ± 0.6009 versus 18.5 ± 0.8851 in control) and solicitation (1.5 ± 0.4282 versus 3.66 ± 0.333 in controls). Lordosis quotient (LQ) (the ratio of lordosis in response to mounting by male), as a measure of receptive behavior was also significantly reduced in fluoxetine treated group as compared to control (67.51 ± 2.276 versus 87.24 ± 1.714).

 

Effect of co administration of fluoxetine and Chlorophytum borivilianum on sexual behavior:

Co-administration of FLX with CB (300 and 500 mg/kg) showed significant increase in hops and darts as compared to FLX treated rats. However, CB-500 mg/kg was found to be more effective (p<0.01) as compared to CB-300 mg/kg (p<0.05). Ear wigglings and solicitations were also significantly increased by FLX+CB-500 mg/kg when compared against FLX treated rats. FLX + CB (300 and 500 mg/kg) groups showed significant increment (p<0.01) in lordosis quotient while CB-100 mg/kg was not significant in improving any of the aforementioned behavioral parameters.

 

DISCUSSION:

A large number of reports suggest that serotonin reuptake inhibitors may reduce libido in humans1, 3. The major purpose of this study was to investigate whether co-administration of hydroalcoholic extract of Chlorophytum borivilianum with fluoxetine has any influence on improving the reduced libido associated with fluoxetine.

 

Female rat sexual behavior is tightly linked to ovulation and the synchronous timing for both events is controlled by the hypothalamic–pituitary–gonadal (HPG) axis with estrogen as the ultimate conductor. Unlike primates, normally cycling female rats show sexual receptivity only during the proestrous (ovulatory) portion of the reproductive cycle. Removal of the ovaries leads to immediate cessation of sexual behavior which can be restored by treatment with estrogen and progesterone2. Thus in this study, various sexual behaviors were studied in OVX female rats primed with EB and P. Also, ovarectomizing the female rats was important, otherwise they would become pregnant and hence useless for use during the study. The study was essentially conducted between 9 a.m to 5 p.m to reduce any other variations.

 

After 2 weeks of administration, fluoxetine significantly reduced various sexual behaviors of OVX female rats primed with EB + P.  Fluoxetine induced a significant reduction in the lordosis quotient as well as in proceptive behaviors. In contrast, both of these parameters were significantly increased by co-administration of CB. The observation that a serotonin reuptake inhibitor reduced lordosis in ovariectomized rats primed with EB + P is well in line with previous studies, suggesting that serotonin exerts a predominantly inhibiting effect on this behavior.

 

The current findings lead to the suggestion that effects of fluoxetine on female sexual dysfunction may result from a disruption of the neuroendocrine axis and increased levels of serotonin. Co-administration of CB at dose level of 300 and 500 mg/kg with fluoxetine for 2 weeks showed significant improvement in various sexual dysfunctions which were induced by fluoxetine, suggesting the possible role of CB in maintaining the levels of serotonin. However, study needs further investigation to know the exact mechanism underlying the effect.

 

Fig 2: Effect of fluoxetine and CB extract on lordosis quotient. n=6, Comparison between control and FLX treated group was made by Student’s‘t’ test while between FLX and FLX + CB (100, 300 and 500 mg/kg) was made by one way analysis of variance (ANOVA) followed by Dunnett’s‘t’ test. #P<0.05, ##p<0.01 against control and *P<0.05, **P<0.01 against FLX.

 

CONCLUSION:

To conclude, the treatment with Chlorophytum borivilianum showed significant improvement in the various sexual dysfunctions in female rats induced by fluoxetine, suggesting its possible use in females with antidepressant induced reduced libido.

 

ACKNOWLEDGEMENTS:

The authors would like to thank Mr.R.Rajendran, Green Chem, Bangalore for providing authenticated hydroalcoholic extract of Chlorophytum borivilianum tubers and Dr.K.G. Bothara, Principal, AISSMS College of Pharmacy, Pune for providing necessary guidance and support.

 

REFERENCES:

1.       Matuszczy JV, Larsson K and Eriksson E. The selective serotonin reuptake inhibitor fluoxetine reduces sexual motivation in male rats. Pharmacol Biochem Behav. 1998; 60(2): 527–32.

2.       Sarkar J et al. Subchronic treatment with fluoxetine attenuates effects of acute fluoxetine on female rat sexual behavior. Brain Res. 2008; 1190: 56-64.

3.       Matuszczy JV, Larsson K and Eriksson E. Subchronic administration of fluoxetine impairs estrous behavior in intact female rats. Neuropsychopharmacol. 1998; 19(6): 492-98.

4.       Sukoff Rizzo SJ, Schechter LE and Rosenzweig-Lipson. A novel approach for predicting antidepressant-induced sexual dysfunction in rats. Psychopharmacol. 2008; 195: 459–67.

5.       Chakraborthy GS and Aeri V. Antidiabetic and antihyperlipidaemic effect of alcoholic extract of Chlorophytum borivilianum roots in alloxan induced diabetic albino rats. J Pharm Res. 2008; 1(1): 29-33.

6.       Thakur M and Dixit VK. A Review on some important medicinal plants of Chlorophytum spp. Pharmacog Rev. 2008; 2(3): 169-72.

7.       Gopalkrishna B, Akki and Patil SH. Preliminary phytochemical investigation and in-vitro antistress activity of safed musli – Chlorophytum borivilianum. Indiam Drugs. 2006; 43(11): 878-80.

8.       Deore SL and Khadabadi SS. In-vitro antimicrobial studies of Chlorophytum borivilianum (liliaceae) root extracts. Asian. J. Microbiol. Biotech. Env. Sc. 2007; 9(4): 807-09.

9.       Panda SK, Sai SC and Bhatnagar SP. Studies on hypoglycaemic and analgesic activities of Chlorophytum borivilianum Sant & Ferz. J Natural Rem. 2007; 7 (1): 31-6.

10.     Deore SL and Khadabadi SS. Antiinflammatory and antioxidant activity of Chlorophytum borivilianum root extracts. Asian J Chem. 2008; 20(2): 983-86.

11.     Thakur M, Bhargava S and Dixit VK. Immunomodulatory activity of Chlorophytum borivilianum Sant. F. eCAM. 2007; 4(4): 419-23.

12.     Thakur M and Dixit VK. Effect of C.borivilianum on androgenic and sexual behavior of male rats. Indian Drugs. 2006; 43: 300-06.

13.     Kenjale R, Shah R and Sathaye S. Effect of Chlorophytum borivilianum on Sexual Behavior and Sperm count in male rats. Phytother Res. 2008; 22: 796-801.

14.     Lopez HH, Wurzel G and Ragen B. The effect of acute bupropion on sexual motivation and behavior in the female rat. Pharmacol Biochem Behav. 2007; 87: 368-79.

15.     Rossler AS et al. The melanocortin agonist, melanotan II, enhances proceptive sexual behaviors in the female rat. Pharmacol Biochem Behav. 2006; 85: 514-21.

 

Received on 15.07.2009

Accepted on 17.09.2009     

© A&V Publication all right reserved

Research J. Pharmacology and Pharmacodynamics 1(3) Nov - Dec.  2009; 130-133