Effect of the beta-adrenergic blockade on intestinal lactate production and glycogen concentration in dogs infused with hexoses.

OBJECTIVES: To investigate effect of beta adrenergic blockade on intestinal lactate production and glycogen concentration in dogs infused with hexoses. METHODS: Experiments were carried out on 35 fasted male anaesthetized dogs weighing between 9 and 16 kg. The animals were divided into 7 (5 dogs per group) groups. Group I dogs served as control and infused with normal saline, groups II-IV were intravenously infused with glucose (1.1 mg/kg/min), fructose (1.1 mg/kg/min) and galactose (1.1 mg/kg/min) respectively while groups V-VII animals were pretreated with propranolol (0.5 mg/kg) and were infused with glucose, fructose or galactose respectively. A vein draining the proximal segment of the jejunum was cannulated along with right and left femoral arteries and veins. Glucose uptake was calculated as the product of jejunal blood flow and the difference between arterial and venous glucose levels (A-V glucose), part of the jejunum tissue was homogenized for estimation of glycogen concentration, and plasma lactate was assayed using lactate colorimetric kit. RESULTS: The result showed significant increase in venous lactate production in response to glucose (78.30 ± 4.57 mg/dL), fructose (60.72 ± 1.82 mg/dL) and galactose (71.70 ± 1.30 mg/dL) when compared with the control group (51.75 ± 1.32 mg/dL) at (p<0.05) with no significant difference in animals pretreated with propranolol. There was no significant difference in glycogen concentration (p>0.05) in animals infused with hexoses only compared with propanolol pretreated group. CONCLUSIONS: Results suggests that one of the possible fates of the enormous amount of glucose taken up by the intestine is conversion to lactate and not glycogen and ß-adrenergic receptor does not affect it.

Uterine contractile activity and fetal outcome in rats treated with vitamin C during late gestational variable stress exposure.

OBJECTIVES: Stress responses vary throughout pregnancy and impact of late gestational variable stress (LGVS) with vitamin C supplementation on uterine contractility is barely explored. This study investigates fetal weight outcome and in-vitro uterine contractile responses to pharmacological agents during LGVS exposure. METHODS: Twenty four nulliparous pregnant rats were divided into four groups of six. During gestation days 10-19, groups 1 & 2 received normal saline and vitamin C (10 mg/kg) respectively. Groups 3 and 4 were exposed to stress (sleep deprivation, predator exposure, immobility, rapid cage changes, noise, and foreign object) with group 4 concurrently supplemented with vitamin C (10 mg/kg). Serum cortisol, oxidative bio-markers, fetal weights and in-vitro contractile responses of excised uterine tissue to acetylcholine (Ach), oxytocin, calcium chloride (CaCl2), potassium chloride (KCl), diclofenac, and magnesium ions were determined. RESULTS: Malondialdehyde activity and cortisol were significantly increased in variable stress only exposed group when compared with control and vitamin C supplemented groups. Fetal body weights, superoxide dismutase and catalase activity were significantly reduced in variable stress only exposed group. Significantly impaired contractile responses to Ach, CaCl2 & KCl in variable stress only exposed group were modulated in vitamin C supplemented groups. Impaired contractile response to oxytocin was however not reversed. Relaxation responses to diclofenac and magnesium ions were statistically unaltered across groups. CONCLUSIONS: Impaired fetal weights and uterine contractile activity to Ach, CaCl2 and KCl during LGVS was modulated by vitamin C supplementation. Impaired oxytocin contractile activity was however unreversed.

Implication of caffeine consumption and recovery on the reproductive functions of adult male Wistar rats.

BACKGROUND: This study assessed the impact of caffeine consumption and recovery on reproductive functions and fertility of Wistar rats. METHODS: Thirty-five adult male Wistar rats were divided into seven groups of five rats each. Group A (control) received distilled water (vehicle), while groups B, C, and D were treated orally with 10 mg/kg body weight (BW), 20 mg/kg BW, and 40 mg/kg BW caffeine, respectively, for 30 days. Groups E, F, and G were treated orally with 10 mg/kg BW, 20 mg/kg BW, and 40 mg/kg BW caffeine, respectively, for 30 days and then allowed to recover for another 30 days. RESULTS: Caffeine caused a decrease in body weight, while recovery groups showed appreciable increase in body weight during recovery. Relative weight of seminal vesicle, prostate, and epididymis decreased dose dependently during treatment but increased during recovery. The liver and kidney weight increased during treatment but reduced during recovery. Sperm count was significantly decreased in both treated and recovery groups. Initial decrease in sperm viability and volume was appreciably reversed during recovery period. Serum level of testosterone increased at high doses, while serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) showed significant decrease. Histological sections of testis in treated groups showed mild congestion of the interstitial blood vessel and subcapsular congestion. However, there was no subcapsular congestion in the recovery groups. All rats in both treated and recovery groups had 100% fertilization success from fertility study. CONCLUSIONS: Suggestively, caffeine treatment for 4 weeks could impair body, reproductive organs weight, sperm characteristics, LH/FSH level, and also testicular cyto-architecture. Effects appeared, however, reversible after caffeine withdrawal.

Mechanism of vasorelaxation induced by Tridax procumbens extract in rat thoracic aorta.

BACKGROUND/AIM: Tridax procumbens (Linn) (Asteraceae) is one of the herbs widely distributed in many parts of the world. Its leaves have long been used for the treatment of hypertension in Nigeria. Previous studies have shown that aqueous leaves of T. procumbens extract (TPE) lowers blood pressure through endothelium-dependent and -independent mechanism in the aortic rings isolated from normotensive rats. The aim of the present study was to further investigate mechanisms of TPE-induced relaxation in the aortic artery by assessing its mechanistic interactions with nitric oxide (NO) synthase, cyclic guanosine monophosphate (cGMP), and cyclic adenosine monophosphate (cAMP). MATERIALS AND METHODS: The aortic artery isolated from healthy, young adult normotensive Wistar albino rats (250-300 g) were pre-contracted with phenylephrine (PE) (10-7 M) and KCl (60 mM) and were treated with various concentrations of aqueous extract of TPE (0.5-9.0 mg/ml). The changes in arterial tension were recorded using Ugo Basile model 7004 coupled to data capsule acquisition system model 17400. The interaction between TPE with cAMP and cGMP inhibitors was also evaluated. RESULTS: The results showed that the TPE (0.5-9.0 mg/ml) significantly (P < 0.05) reduced the contraction induced by PE in a concentration-dependent manner. The vasorelaxant effect caused by the TPE was significantly (P < 0.05) attenuated with pre-incubation of cGMP (Rp-8Br PET cGMPS) and cAMP (Rp-AMP) inhibitor, respectively. CONCLUSION: These results suggest that TPE causes vasodilatory effects in a concentration-dependent manner in the isolated rat aortic artery. The mechanism of action of TPE is complex. A part of its relaxing effect is mediated directly by blocking or modulating cGMP and cAMP.

Comprehensive assessment of the effect of Sphenocentrum jollyanum root extract on male reproductive activity in albino rats.

Aim: To evaluate the effect of methanol extract from the Sphenocentrum jollyanum root on male reproductive activity. Methods: Male albino rats were treated orally with distilled water (vehicle for the extract; control) and 50, 100 and 150 mg kg-1 body weight of Sphenocentrum jollyanum root extract for 8 weeks. Each group had its own recovery. Rats were killed 24 h after the last treatment. Caudal epididymal sperm count, motility, viability, morphology and organ weights were determined. Hematological indices, serum proteins, enzymes, testicular superoxide dismutase (SOD) activity, and testicular and epididymal histology were determined. Results: Compared with the control, the extract caused a dose dependent significant (P < 0.05) reduction in progressive motility of spermatozoa, viability and total sperm counts. The number of abnormal spermatozoa and epididymal volume were not statistically significant. There was a significant increase (P < 0.05) in serum testosterone levels in rats treated with 50 (P < 0.01) and 100 mg kg-1 (P < 0.05) of Sphenocentrum jollyanum. There was a significant (P < 0.05) increase in red blood cell count, packed cell volume and hemoglobin concentration, whereas there was no change in white blood cell count, mean total serum protein, albumin and globulin in the sera of Sphenocentrum jollyanum treated rats when compared with the control. The extract caused a significant decrease (P < 0.05) in serum aspartate and alanine aminotransferase activities with a significant increase (P < 0.05) in testicular SOD activity at a dose of 50 mg kg-1 bodyweight. Testicular cytoarchitecture of the extract treated rats showed degeneration of seminiferous tubules, whereas regeneration of germinal epithelium and restructuring of the germinal interstitium occurred in the recovery rats. No lesions were observed in the epididymis of the rats. Conclusion: The results suggest that methanol extract of the Sphenocentrum jollyanum root could produce harmful effects on reproductive functions in male albino rats which can be attributed to poor sperm quantity (epididymal sperm count), quality (sperm motility, viability and morphology) and testicular degeneration. The steroidogenic potential of the plant could explain its use as an aphrodisiac agent. (Reprod Med Biol 2006; 5: 283-292).