L-ergothioneine and metformin alleviates liver injury in experimental type-2 diabetic rats via reduction of oxidative stress, inflammation, and hypertriglyceridemia.

Type-2 diabetes (T2D) is associated with liver toxicity. L-ergothioneine (L-egt) has been reported to reduce toxicity in tissues exposed to injury, while metformin is commonly prescribed to manage T2D. Hence, this study evaluates the hepatoprotective role of L-egt, with or without metformin, in T2D male rats. A total of 36 adult male Sprague-Dawley rats were randomly divided into non-diabetic (n = 12) and diabetic (n = 24) groups. After induction of diabetes, animals were divided into six groups (n = 6) and treated orally either with deionized water, L-egt (35 mg/kg bodyweight (bwt)), metformin (500 mg/kg bwt), or a combination of L-egt and metformin for 7 weeks. Body weight and blood glucose were monitored during the experiment. Thereafter, animals were euthanized and liver tissue was excised for biochemical, ELISA, real-time quantitative PCR, and histopathological analysis. L-egt with or without metformin reduced liver hypertrophy, liver injury, triglycerides, oxidative stress, and inflammation. Also, L-egt normalized mRNA expression of SREBP-1c, fatty acid synthase, nuclear factor kappa B, transforming growth factor ß1, nuclear factor erythroid 2-related factor 2, and sirtuin-1 in diabetic rats. Furthermore, co-administration of L-egt with metformin to diabetic rats reduced blood glucose and insulin resistance. These results provide support to the therapeutic benefits of L-egt in the management of liver complications associated with T2D.

Adipsin in the pathogenesis of cardiovascular diseases.

Adipsin is an adipokine predominantly synthesized in adipose tissues and released into circulation. It is also known as complement factor-D (CFD), acting as the rate-limiting factor in the alternative complement pathway and exerting essential functions on the activation of complement system. The deficiency of CFD in humans is a very rare condition. However, complement overactivation has been implicated in the etiology of numerous disorders, including cardiovascular disease (CVD). Increased circulating level of adipsin has been reported to promote vascular derangements, systemic inflammation, and endothelial dysfunction. Prospective and case-control studies showed that this adipokine is directly associated with all-cause death and rehospitalization in patients with coronary artery disease. Adipsin has also been implicated in pulmonary arterial hypertension, abdominal aortic aneurysm, pre-eclampsia, and type-2 diabetes which is a major risk factor for CVD. Importantly, serum adipsin has been recognized as a unique prognostic marker for assessing cardiovascular diseases. At present, there is paucity of experimental evidence about the precise role of adipsin in the etiology of CVD. However, this mini review provides some insight on the contribution of adipsin in the pathogenesis of CVD and highlights its role on endothelial, smooth muscle and immune cells that mediate cardiovascular functions.

Surfactant protein A promotes western diet-induced hepatic steatosis and fibrosis in mice.

Metabolic dysfunction-associated steatotic liver disease (MASLD) remains the most common cause of liver disease in the United States due to the increased incidence of metabolic dysfunction and obesity. Surfactant protein A (SPA) regulates macrophage function, strongly binds to lipids, and is implicated in renal and idiopathic pulmonary fibrosis (IPF). However, the role of SPA in lipid accumulation, inflammation, and hepatic fibrosis that characterize MASLD remains unknown. SPA deficient (SPA-/-) and age-matched wild-type (WT) control mice were fed a Western diet for 8 weeks to induce MASLD. Blood and liver samples were collected and used to analyze pathological features associated with MASLD. SPA expression was significantly upregulated in livers of mice with MASLD. SPA deficiency attenuated lipid accumulation along with downregulation of genes involved in fatty acid uptake and reduction of hepatic inflammation as evidenced by the diminished macrophage activation, decreased monocyte infiltration, and reduced production of inflammatory cytokines. Moreover, SPA-/- inhibited stellate cell activation, collagen deposit, and liver fibrosis. These results highlight the novel role of SPA in promoting fatty acid uptake into hepatocytes, causing excessive lipid accumulation, inflammation, and fibrosis implicated in the pathogenesis of MASLD.

Cardiometabolic Disorder and Erectile Dysfunction.

Erectile dysfunction (ED), which is defined as the inability to attain and maintain a satisfactory penile erection to sufficiently permit sexual intercourse, is a consequence and also a cause of cardiometabolic disorders like diabetes mellitus, systemic hypertension, central obesity, and dyslipidemia. Although there are mounting and convincing pieces of evidence in the literature linking ED and cardiometabolic disorders, impairment of nitric oxide-dependent vasodilatation seems to be the primary signaling pathway. Studies have also implicated the suppression of circulating testosterone, increased endothelin-1, and hyperactivation of Ang II/ATIr in the pathogenesis of ED and cardiometabolic disorders. This study provides comprehensive details of the association between cardiometabolic disorders and ED and highlights the mechanisms involved. This would open areas to be explored as therapeutic targets in the management of ED and cardiometabolic disorders. It also provides sufficient evidence establishing the need for the management of cardiometabolic disorders as an adjunct therapy in the management of ED.

Cardioprotective Effects and in-silico Antioxidant Mechanism of L-Ergothioneine in Experimental Type-2 Diabetic Rats.

BACKGROUND: Diabetic cardiotoxicity is commonly associated with oxidative injury, inflammation, and endothelial dysfunction. L-ergothioneine (L-egt), a diet-derived amino acid, has been reported to decrease mortality and risk of cardiovascular injury, provides cytoprotection to tissues exposed to oxidative damage, and prevents diabetes-induced perturbation. OBJECTIVE: This study investigated the cardioprotective effects of L-egt on diabetes-induced cardiovascular injuries and its probable mechanism of action. METHODS: Twenty-four male Sprague-Dawley rats were divided into non-diabetic (n = 6) and diabetic groups (n = 18). Six weeks after the induction of diabetes, the diabetic rats were divided into three groups (n = 6) and administered distilled water, L-egt (35mg/kg), and losartan (20mg/kg) by oral gavage for six weeks. Blood glucose and mean arterial pressure (MAP) were recorded pre-and post-treatment, while biochemical, ELISA, and RT-qPCR analyses were conducted to determine inflammatory, injury-related and antioxidant biomarkers in cardiac tissue after euthanasia. Also, an in-silico study, including docking and molecular dynamic simulations of L-egt toward the Keap1- Nrf2 protein complex, was done to provide a basis for the molecular antioxidant mechanism of Legt. RESULTS: Administration of L-egt to diabetic animals reduced serum triglyceride, water intake, MAP, biomarkers of cardiac injury (CK-MB, CRP), lipid peroxidation, and inflammation. Also, Legt increased body weight, antioxidant enzymes, upregulated Nrf2, HO-1, NQO1 expression, and decreased Keap1 expression. The in-silico study showed that L-egt inhibits the Keap1-Nrf2 complex by binding to the active site of Nrf2 protein, thereby preventing its degradation. CONCLUSION: L-egt protects against diabetes-induced cardiovascular injury via the upregulation of the Keap1-Nrf2 pathway and its downstream cytoprotective antioxidants.

Highly active antiretroviral therapy-silver nanoparticle conjugate interacts with neuronal and glial cells and alleviates anxiety-like behaviour in streptozotocin-induced diabetic rats.

The inception of highly active antiretroviral therapy (HAART) has changed the management of human immunodeficiency virus (HIV) positive patients, with an improvement in life expectancy. However, neurological complications associated with high dosage and chronic administration of HAART have not been fully addressed. Therefore, this study evaluated the potential benefits of silver nanoparticles (AgNPs) conjugated-HAART (HAART-AgNPs) and its interaction with neuronal and glial cells in type-2 diabetic rats. Forty-two (n = 42) adult male Sprague-Dawley rats (250 ± 13 g) were divided into non-diabetic and diabetic groups. Each rat was administered with either distilled water, HAART, or HAART-AgNPs for eight weeks. After that, the prefrontal cortex (PFC) was excised for immunohistochemical, biochemical, and ultrastructural analysis. The formulated HAART-AgNPs were characterised by Ultraviolet-Visible, Transmission electron microscope, Energy Dispersive X-ray and Fourier transform infrared spectroscopy. Of the various concentrations of HAART-AgNPs, 1.5 M exhibited 20.3 nm in size and a spherical shape was used for this study. Administration of HAART-AgNPs to diabetic rats significantly decreased (p < 0.05) blood glucose level, number of faecal pellets, malondialdehyde (MDA), tumour necrosis factor-alpha (TNF-α), Interleukin-1 beta (IL-1ß) compared with HAART-treated diabetic rats. Notably, there was a significant increase (p < 0.05) in antioxidant biomarkers (SOD and GSH), improvement in PFC-glial fibrillary acid protein (PFC-GFAP) positive cells and alleviation of anxiety-like behaviour in HAART-AgNPs treated diabetic rats. These results showed that HAART-AgNPs alleviates the anxiogenic effect and neuronal toxicity aggravated by HAART exposure via the reduction of oxidative and neuroinflammatory injury as well as preserving PFC GFAP-positive cells and neuronal cytoarchitecture.

Evaluation of tenofovir disoproxil fumarate loaded silver nanoparticle on testicular morphology in experimental type-2 diabetic rats.

Reproductive derangement and metabolic disorders in human immunodeficiency virus (HIV) infected persons require a nanoparticle delivery system to convey antiretroviral drugs to the anatomical sanctuary such as testis. This study investigated the effects of tenofovir disoproxil fumarate (TDF) loaded silver nanoparticles (AgNPs) on the testicular oxidative stress, inflammatory cytokines and histology in male diabetic rats. Thirty-six Sprague-Dawley rats weighing 230 ± 20 g were randomly divided into diabetic and non-diabetic groups (n = 18). Diabetes was induced using the fructose-streptozotocin (Frt-STZ) rat model. Both groups were further divided into three (n = 6) and administered distilled water, TDF, or TDF-AgNP. Results obtained with the TDF-AgNP administration showed a significant increase (p < .05) in the reduced glutathione and catalase levels. Tumour necrosis factor-alpha and interleukin 6 were reduced in diabetic rats administered TDF-AgNP. More so, administration of TDF-AgNP to diabetic rats improved testicular histoarchitecture in diabetic rats. In addition, diabetic rats administered TDF-AgNP showed a significant reduction (p < .05) in blood glucose levels. TDF-AgNP to diabetic rats enhanced testicular antioxidant enzyme, reduced testicular inflammation, and alleviated structural derangements in the testis. Thus, the application of AgNP to deliver TDF may alleviate testicular toxicity and subsequently cater for neglected reproductive dysfunction during the management of HIV infection.

Awareness and Attitudes of Secondary School Students about Physiology Discipline in Southwest Region, Nigeria.

Physiology remains one of the core disciplines on which all biological and medical sciences were founded. In Nigeria, it is known that most students study Physiology at the undergraduate level by chance and not by choice and end up performing poorly, which could be mainly due to low awareness and knowledge of the discipline, its opportunities, and prospects. Therefore, this study investigated the awareness, attitude, and knowledge about physiology among senior secondary school students in Southwest Nigeria. A cross-sectional of 544 students in science-based senior secondary schools in south-west Nigeria were sampled. Our results showed a high level of awareness, with television being the dominant medium of information. However, knowledge of Physiology was low, while most of the students also showed interest in knowing more about it. Although gender does not seem to influence the level of knowledge, females had a better attitude towards learning about physiology. Similarly, residence did not affect attitude, howbeit associated with the level of knowledge. In conclusion, the high awareness and low knowledge observed in this study would give insights to educate students at the early stages of education about the opportunity and prospects of Physiology and other science-related disciplines.

Testicular ultrastructure and hormonal changes following administration of tenofovir disoproxil fumarate-loaded silver nanoparticle in type-2 diabetic rats.

Reproductive dysfunctions (RDs) characterized by impairment in testicular parameters, and metabolic disorders such as insulin resistance and type 2 diabetes mellitus (T2DM) are on the rise among human immunodeficiency virus (HIV) patients under tenofovir disoproxil fumarate (TDF) and highly active antiretroviral therapy (HAART). These adverse effects require a nanoparticle delivery system to circumvent biological barriers and ensure adequate ARVDs to viral reservoir sites like testis. This study aimed to investigate the effect of TDF-loaded silver nanoparticles (AgNPs), TDF-AgNPs on sperm quality, hormonal profile, insulin-like growth factor 1 (IGF-1), and testicular ultrastructure in diabetic rats, a result of which could cater for the neglected reproductive and metabolic dysfunctions in HIV therapeutic modality. Thirty-six adult Sprague-Dawley rats were assigned to diabetic and non-diabetic (n = 18). T2DM was induced by fructose-streptozotocin (Frt-STZ) rat model. Subsequently, the rats in both groups were subdivided into three groups each (n = 6) and administered distilled water, TDF, and TDF-AgNP. In this study, administration of TDF-AgNP to diabetic rats significantly reduced (p < 0.05) blood glucose level (268.7 ± 10.8 mg/dL) from 429 ± 16.9 mg/dL in diabetic control and prevented a drastic reduction in sperm count and viability. More so, TDF-AgNP significantly increased (p < 0.05) Gonadotropin-Releasing Hormone (1114.3 ± 112.6 µg), Follicle Stimulating Hormone (13.2 ± 1.5 IU/L), Luteinizing Hormone (140.7 ± 15.2 IU/L), testosterone (0.2 ± 0.02 ng/L), and IGF-1 (1564.0 ± 81.6 ng/mL) compared to their respective diabetic controls (383.4 ± 63.3, 6.1 ± 1.2, 76.1 ± 9.1, 0.1 ± 0.01, 769.4 ± 83.7). Also, TDF-AgNP treated diabetic rats presented an improved testicular architecture marked with the thickened basement membrane, degenerated Sertoli cells, spermatogenic cells, and axoneme. This study has demonstrated that administration of TDF-AgNPs restored the function of hypothalamic-pituitary-gonadal axis, normalized the hormonal profile, enhanced testicular function and structure to alleviate reproductive dysfunctions in diabetic rats. This is the first study to conjugate TDF with AgNPs and examined its effects on reproductive indices, local gonadal factor and testicular ultrastructure in male diabetic rats with the potential to cater for neglected reproductive dysfunction in HIV therapeutic modality.

L-ergothioneine and its combination with metformin attenuates renal dysfunction in type-2 diabetic rat model by activating Nrf2 antioxidant pathway.

L-ergothioneine (L-egt) is a bioactive compound recently approved by the food and drug administration as a supplement. L-egt exerts potent cyto-protective, antioxidant and anti-inflammatory properties in tissues exposed to injury, while metformin is a first-line prescription in type-2 diabetes. Therefore, the present study investigated the protective effect of L-egt alone, or combined with metformin, on renal damage in a type-2 diabetic (T2D) rat model. T2D was induced in male Sprague-Dawley rats using the fructose-streptozotocin rat model. L-egt administration, alone or combined with metformin, began after confirming diabetes and was administered orally for seven weeks. After the experiment, all animals were euthanized by decapitation, blood samples were collected, and both kidneys were excised. Biochemical analysis, Enzyme-link Immunoassay (ELISA), Reverse transcriptase quantitative polymerase chain reaction (RT-qPCR), western blotting, and histological analyses were done to evaluate various biomarkers and structural changes associated with renal damage. Untreated diabetic rats showed loss of kidney functions characterized by increased serum creatinine, blood urea nitrogen, proteinuria, triglycerides, lipid peroxidation, inflammation, and decreased antioxidant enzymes. Histological evaluation showed evidence of fibrosis, mesangial expansion, and damaged basement membrane in the nephrons. However, L-egt alleviates these functional and structural derangements in the kidney, while co-administration with metformin reduced hyperglycemia and improves therapeutic outcomes. Furthermore, L-egt treatment significantly increased the expression of major antioxidant transcription factors, cytoprotective genes and decreased the expression of inflammatory genes in the kidney. Thus, combining L-egt and metformin may improve therapeutic efficacy and be used as an adjuvant therapy to alleviate renal damage in type-2 diabetes.

Increase in SARS-CoV-2 infected biomedical waste among low middle-income countries: environmental sustainability and impact with health implications.

Studies have shown that severe acute respiratory syndrome corona virus-2 (SARS-CoV-2) is a highly infectious disease, with global deaths rising to about 360,438 as of 28 May 2020. Different countries have used various approaches such as lockdown, social distancing, maintenance of personal hygiene, and increased establishment of testing and isolation centers to manage the pandemic. Poor biomedical waste (BMW) management, treatment, and disposal techniques, especially SARS-CoV-2 infected BMW, may threaten the environmental and public health in most developing countries and, by extension, impact the economic status of individuals and the nation at large. This may increase the potential for the transmission of air/blood body fluid-borne pathogens, increase the growth of microorganisms, risk of mutagenesis, and upsurge of more virulent strain. In contrast, uncontrolled substandard burning could increase the potential spread of nosocomial infection and environmental exposure to toxic organic compounds, heavy metals, radioactive, and genotoxic bio-aerosols which might be present in the gaseous, liquid, and solid by-products. The paucity of understanding of pathophysiology and management of the SARS-CoV-2 pandemic has also necessitated the need to put in place appropriate disposal techniques to cater for the sudden increase in the global demand for personal protective equipment (PPE) and pharmaceutical drugs to manage the pandemic and to reduce the risk of preventable infection by the waste. Therefore, there is a need for adequate sensitization, awareness, and environmental monitoring of the impacts of improper handling of SARS-CoV-2 infected BMWs. Hence, this review aimed to address the issues relating to the improper management of increased SARS-CoV-2 infected BMW in low middle-income countries (LMICs).

Highly active antiretroviral therapy conjugated silver nanoparticle ameliorates testicular injury in type-2 diabetic rats.

Despite advances in managing human immunodeficiency virus (HIV) infection and success in the treatment prognosis using highly active antiretroviral therapy (HAART). The clinical efficacy of this regimen has been associated with increased adverse effects such as metabolic derangements and reproductive dysfunctions. These adverse effects necessitate a nanoparticle delivery vehicle like silver nanoparticles (AgNPs), a multi-functional drug delivery system, to transport the HAART to the viral reservoir site like testis. This study was therefore designed to evaluate the effects of HAART loaded AgNPs (HAART-AgNPs) on testicular oxidative stress markers, an inflammatory biomarker, and histomorphology in a rat model of diabetes. Thirty-six adult male Sprague-Dawley rats were randomly divided into two groups (n = 18) non-diabetic and fructose-streptozotocin (Frt-STZ) induced type 2 diabetes (T2DM). Thereafter, both groups were subdivided into three (n = 6) and treated with distilled water, HAART and HAART-AgNPs. HAART-AgNPs caused a significant increase (p < 0.05) in catalase (23.43 ± 0.92) level vs diabetic control (16.95 ± 1.04). Also, HAART-AgNP caused a significant reduction (p < 0.05) in malondialdehyde, interleukin-6 and blood glucose levels (1.94 ± 0.06, 93.65 ± 3.6, 287.33 ± 22.85 respectively), compared to their respective diabetic control values (2.18 ± 0.12, 143.4 ± 9.2, 372.16 ± 23.16). Furthermore, HAART-AgNPs mitigated tubular atrophy, basement membrane thickening, interstitial distension, fibrous elemental distortion and peri-interstitial tissue alterations in the testis of diabetic rats. The results from this study showed that administration of HAART-AgNPs to diabetic rats reduced testicular inflammation, improved glycaemic control, antioxidant status, and testicular histology. Therefore, conjugation of AgNP with HAART may cater for the reproductive dysfunction during the management of HIV infection.

Silver Nanoparticles Conjugate Attenuates Highly Active Antiretroviral Therapy-Induced Hippocampal Nissl Substance and Cognitive Deficits in Diabetic Rats.

BACKGROUND: The application of nanomedicine to antiretroviral drug delivery holds promise in reducing the comorbidities related to long-term systemic exposure to highly active antiretroviral therapy (HAART). However, the safety of drugs loaded with silver nanoparticles has been debatable. This study is aimed at evaluating the effects of HAART-loaded silver nanoparticles (HAART-AgNPs) on the behavioural assessment, biochemical indices, morphological, and morphometric of the hippocampus in diabetic Sprague-Dawley rats. METHODS: Conjugated HAART-AgNPs were characterized using FTIR spectroscopy, UV spectrophotometer, HR-TEM, SEM, and EDX for absorbance peaks, size and morphology, and elemental components. Forty-eight male SD rats (250 ± 13 g) were divided into nondiabetic and diabetic groups. Each group was subdivided into (n = 8) A (nondiabetic+vehicle), B (nondiabetic+HAART), C (nondiabetic+HAART-AgNPs), D (diabetic+vehicle), E (diabetic+HAART), and F (diabetic+HAART-AgNPs). Morris water maze, Y-maze test, and weekly blood glucose levels were carried out. Following the last dose of 8-week treatment, the rats were anaesthetized and euthanized. Brain tissues were carefully removed and postfixed for Nissl staining histology. RESULTS: 1.5 M concentration of HAART-AgNPs showed nanoparticle size 20.3 nm with spherical shape. HAART-AgNPs revealed 16.89% of silver and other elemental components of HAART. The diabetic control rats showed a significant increase in blood glucose, reduced spatial learning, positive hippocampal Nissl-stained cells, and a significant decrease in GSH and SOD levels. However, administration of HAART-AgNPs to diabetic rats significantly reduced blood glucose level, improved spatial learning, biochemical indices, and enhanced memory compared to diabetic control. Interestingly, diabetic HAART-AgNP-treated rats showed a significantly improved memory, increased GSH, SOD, and number of positive Nissl-stained neurons compared to diabetic-treated HAART only. CONCLUSION: Administration of HAART to diabetic rats aggravates the complications of diabetes and promotes neurotoxic effects on the experimental rats, while HAART-loaded silver nanoparticle (HAART-AgNP) alleviates diabetes-induced neurotoxicity.

Cocos nucifera L. oil alleviates lead acetate-induced reproductive toxicity in sexually-matured male Wistar rats.

OBJECTIVES: Lead primarily affects male reproductive functions via hormonal imbalance and morphological damage to the testicular tissue with significant alteration in sperm profile and oxidative markers. Though, different studies have reported that Cocos nucifera L. oil has a wide range of biological effects, this study aimed at investigating the effect of Cocos nucifera L. oil on lead acetate-induced reproductive toxicity in male Wistar rats. METHODS: Twenty (20) sexually matured male Wistar rats (55-65 days) were randomly distributed into four groups (n=5). Group I (negative control)-distilled water orally for 56 days, Group II (positive control)-5 mg/kg bwt lead acetate intraperitoneally (i.p.) for 14 days, Group III-6.7 mL/kg bwt Cocos nucifera L. oil orally for 56 days and Group IV-lead acetate intraperitoneally (i.p.) for 14 days and Cocos nucifera L. oil for orally for 56 days. Rats were sacrificed by diethyl ether, after which the serum, testis and epididymis were collected and used for semen analysis, biochemical and histological analysis. RESULTS: The lead acetate significantly increases (p<0.05) testicular and epididymal malondialdehyde (MDA) levels, while a significant reduction (p<0.05) in sperm parameters, organ weight, testosterone and luteinizing hormone was observed when compared with the negative control. The coadministration of Cocos nucifera oil with lead acetate significantly increases (p<0.05) testosterone, luteinizing hormone, sperm parameters and organ weight, with a significant decrease (p<0.05) in MDA levels compared with positive control. Histological analysis showed that lead acetate distorts testicular cytoarchitecture and germ cell integrity while this was normalized in the cotreated group. CONCLUSIONS: Cocos nucifera oil attenuates the deleterious effects of lead acetate in male Wistar rats, which could be attributed to its polyphenol content and antioxidant properties.

Testis and blood-testis barrier in Covid-19 infestation: role of angiotensin-converting enzyme 2 in male infertility.

Severe acute respiratory syndrome coronavirus 2 (SARS- CoV-2) that causes COVID-19 infections penetrates body cells by binding to angiotensin-converting enzyme-2 (ACE2) receptors. Evidence shows that SARS-CoV-2 can also affect the urogenital tract. Hence, it should be given serious attention when treating COVID-19-infected male patients of reproductive age group. Other viruses like HIV, mumps, papilloma and Epstein-Barr can induce viral orchitis, germ cell apoptosis, inflammation and germ cell destruction with attending infertility and tumors. The blood-testis barrier (BTB) and blood-epididymis barrier (BEB) are essential physical barricades in the male reproductive tract located between the blood vessel and seminiferous tubules in the testes. Despite the significant role of these barriers in male reproductive function, studies have shown that a wide range of viruses can still penetrate the barriers and induce testicular dysfunctions. Therefore, this mini-review highlights the role of ACE2 receptors in promoting SARS-CoV-2-induced blood-testis/epididymal barrier infiltration and testicular dysfunction.

Comparative evaluation of the aphrodisiac efficacy of sildenafil and Carpolobia lutea root extract in male rabbits.

AIMS: In spite of the folkloric use of the root of Carpolobia lutea as a sexual stimulant in man, there has been limited scientific proof of its efficacy. This study compares the efficacy of methanol extract of C. lutea root (MECLR) and sildenafil on the sexual activity of male rabbits. METHODS: 20 adult male rabbits were grouped into four of five rabbits each. Groups 1-4 were treated orally for 28 days with 2 ml/kg 1% Tween-20 (vehicle), 40 mg/kg MECLR, 80 mg/kg MECLR, and 0.5 mg/kg sildenafil citrate (SC), respectively. Sexual activities of males from each group were assessed by cohabiting them with sexually receptive female at estrus on days 0, 1, 3, and 5 using digital camera mounted on mating arena. Serum testosterone and nitric oxide concentration of the corpora cavernosa homogenates were also determined. RESULTS: MECLR caused a dose-dependent significant increase in mount frequency, intromission frequency and ejaculatory latency (EL) while it reduced mount latency, intromission latency and post EL (similar to SC) when compared with the control. MECLR also caused significant increase in nitric oxide concentration in corpora cavernosa but no change in serum testosterone concentration. CONCLUSIONS: Results suggest that MECLR enhances male sexual activity possibly by augmenting nitric oxide concentration. This study thus provides a novel scientific rationale for the use of C. lutea in the management of penile erectile dysfunction and impaired libido.