**The Effects of Sildenafil Citrate on the Liver and Kidneys of Adult Wistar Rats (***Rattus norvegicus***) – A Histological Study**

Andrew Osayame Eweka1 and Abieyuwa Eweka2

*1Department of Anatomy, School of Basic Medical Sciences, College of Medical Sciences, University of Benin, Benin City, Edo State, 2School of Nursing, University of Benin Teaching Hospital, Benin City Edo State, Nigeria* 

## **1. Introduction**

116 Sexual Dysfunctions – Special Issue

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Sildenafil citrate is widely used as an effective and safe oral treatment for erectile dysfunction of various etiologies (Goldstein et al., 1998; Cheitlin et al., 1999; Benchekroun et al., 2003). It is a potent and selective inhibitor of phosphodiesterase type 5 enzymes that acts to break down cyclic guanosine monophosphate (cGMP) (Boolell et al., 1996). The medication amplifies the effect of sexual stimulation by retarding the degradation of this enzyme. Sildenafil has been found effective in several subpopulations of men with erectile dysfunction, including sufferers from diabetes (Basu and Ryder, 2004), hypertension (Feldman et al., 1999), spinal cord injuries (Hultling et al., 2000; Deforge et al., 2006), multiple sclerosis (Fowler et al., 2005), depression (Seidman et al., 2001; Rosen et al., 2004; Tignol et al., 2004; Fava et al., 2006), PTSD (Orr et al., 2006), and schizophrenia (Aviv et al., 2004; Gopalakrishnan et al., 2006), men after resection of the prostate or radical prostatectomy (Nandipati et al., 2006), after renal transplant (Sharma et al., 2006), men on dialysis (Dachille et al., 2006), and men aged 65 years and older (Wagner et al., 2001; Carson, 2004).

 Psychogenic erectile dysfunction (ED) patients are excellent candidates for sildenafil citrate therapy due to the intact neurovascular pathway. Nevertheless, the drug has been reported to be effective only in about 78% of patients with psychogenic ED (McMahon et al., 2000). It is likely that performance anxiety and sympathetic overtone are the cause of this unresponsiveness to sildenafil citrate during awakening, though data supporting this assumption are lacking (Rosen, 2001). The drug has been found to be effective and well tolerated in men with mild to moderate erectile dysfunction of no clinically identifiable organic cause (Eardley, 2001).

With the presence of PDE5 in choroidal and retinal vessels sildenafil citrate increase choroidal blood flow and cause vasodilation of the retinal vasculature. The most common symptoms are a blue tinge to vision and an increased sensitivity to light (Kerr and Danesh-Meyer, 2009). Adverse effects include headache, visual and retinal disturbances, dizziness and pupil-sparing third nerve palsy (Monastero et al., 2001). There have been reports of non-arteritic anterior ischaemic optic neuropathy and serous macular detachment in users of PDE5 inhibitors; although a causal relationship has not been conclusively shown. Despite

The Effects of Sildenafil Citrate on the Liver

**2. Materials and methods** 

before the experiment started.

histological studies.

laboratory.

(McClatchey, 1994)

**2.5 Statistical analysis** 

**2.4 Approval**

**2.2 Histological study**

**2.1 Sildenafil citrate administration** 

**2.3 Liver enzyme assay and other metabolic panel** 

and Kidneys of Adult Wistar Rats (*Rattus norvegicus*) – A Histological Study 119

Twenty-four (24) adult Wistar rats of both sexes, weighing between 220.5g and 233.8g, with an average weight of 222.3g were randomly assigned into three treatment (n=18) and control (n=6) groups. The rats were obtained and maintained in the Animal holdings of the Department of Anatomy, School of Basic Medical Sciences, University of Benin, Benin city, Nigeria. They were fed with growers' mash obtained from Edo feed and flour mill limited, Ewu, Edo State and given water and feed ad libitum. The rats were acclimatized for 4 weeks

The rats in the treatment groups (A, B, & C) received respectively, 0.25mg/kg, 0.70mg/kg and 1.43mg/kg body weight of Sildenafil citrate base dissolved in distilled water daily for 6 weeks, through orogastric feeding tube, while that of the control group D, received equal volume of distilled water daily during the period of the experiment. The rats were sacrificed by cervical dislocation on day forty-three of the experiment. The liver and kidneys of the animals in each group were dissected out and quickly fixed in 10% formal saline for general

The liver and Kidney tissues were dehydrated in an ascending grade of alcohol (ethanol), cleared in xylene and embedded in paraffin wax. Serial sections of 7 microns thick were obtained using a rotatory microtome. The deparaffinised sections were stained routinely with hematoxylin and eosin reagent. Photomicrographs of the specimens were obtained using digital research photographic microscope in the University of Benin research

Blood samples were collected from all the rats within different treatment groups through the orbital venous plexuses on the last day of the experiment under chloroform anaesthesia. Blood serum was separated by centrifugation at 3000 rpm for 15 min. Serum was analysed colorimetrically for total protein, albumin, transaminases (aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Blood samples were also collected and analyzed for blood urea nitrogen (BUN) and serum creatinine (Scr) by using the commercial kits

This study was given consent and approval for the methodology and other ethical issues

The results were expressed as mean ±SD. Data obtained from liver function test, blood urea nitrogen (BUN) and serum creatinine (Scr) were subjected to statistical analysis using one way analysis of variance (ANOVA) then followed with post hoc test (Least Square

concerning the work by the University of Benin Research Ethics Ccommittee.

Deviation), P value of less than 0.05 was considered significant.

the role of cGMP in the production and drainage of aqueous humor these medications do not appear to alter intraocular pressure and are safe in patients with glaucoma. All PDE5 inhibitors weakly inhibit PDE6 located in rod and cone photoreceptors resulting in mild and transient visual symptoms that correlate with plasma concentrations. Psychophysical tests reveal no effect on visual acuity, visual fields or contrast sensitivity; however, some studies show a mild and reversible impairment of blue-green colour discrimination. PDE5 inhibitors transiently alter retinal function on electroretinogram testing but do not appear to be retinotoxic. Despite the role of cyclic nucleotides in tear production there is no detrimental effect on tear film quality. Based on the available evidence PDE5 inhibitors have a good ocular safety profile (Kerr and Danesh-Meyer, 2009).

It has been reported that sildenafil citrate significantly improves nocturnal penile erections in sildenafil non-responding patients with psychogenic erectile dysfunction (Abdel-Naser et al., 2004). Several pharmacological and physiological properties of sildenafil have been described (Cheitlin et al., 1999; Aviv et al., 2004; Galie et al., 2005; Hoeper et al., 2006)

In Nigeria, most individuals often use sildenafil citrate indiscriminately for sexual arousal. There is a growing apprehension that it could be harmful or injurious to the body. Though sildenafil is currently being used to treat erectile dysfunction in patients with multiple sclerosis, Parkinson disease, multisystem atrophy, and spinal cord injury by improving their neurologically related erectile dysfunction, conversely, it has been implicated in a number of neurological problems, such as intracerebral hemorrhage, migraine, seizure, transient global amnesia, nonarteritic anterior ischemic optic neuropathy, macular degeneration, branch retinal artery occlusion, and ocular muscle palsies. Thus, preclinical and very limited clinical data suggest that sildenafil may have therapeutic potential in selected neurological disorders. However, numerous reports are available regarding neurological adverse events ascribed to the drug. Although sildenafil shows some promise as a therapeutic agent in selected neurological disorders, well-designed clinical trials are needed before the agent can be recommended for use in any neurological disorder (Farooq et al., 2008).

The liver is the largest glandular organ of the body, weighing between 1.4-1.6kg. It lies below the diaphragm in the thoracic region of the abdomen. It plays a major role in metabolism and has a number of functions in the body, including glycogen storage, plasma protein synthesis, production of bile; an alkaline compound which aids in digestion, and detoxification of most substances (Gartner and Hiatt, 2000).

The Kidney is a paired organ located in the posterior abdominal wall, whose functions include the removal of waste products from the blood and regulation of the amount of fluid and electrolytes balance in the body. As in humans, the majority of drugs administered are eliminated by a combination of hepatic metabolism and renal excretion (Katzung 1998). The kidney also plays a major role in drug metabolism, but its major importance to drugs is still its excretory functions.

Since the liver and kidneys are involved in the performance of these varied functions they may be susceptible to injury particularly in situation of toxicity. This work is carried out to investigate the histological effects of Sildenafil citrate on the liver and kidneys of adult Wistar rat. Though there are little or no literature report of toxicity of this drug on these two organs, but because they are vital organs in the body it is worthwhile to study its effects on them. Though Daghfous et al., in 2005 reported that sildenafil-induced liver disease.

This study will further corroborate or disprove the toxic effects of Sildenafil citrate in organs other than sex organs, with a view to advising the consumers on the inherent dangers of excessive consumption of the aphrodisiac.
