Biomedical subjects

P G Adaikan

Publications and source records attributed to P G Adaikan.

At least 19 recordsLinked to original sources

PubMed2006

Characterization of hypertriglyceridemia-induced erectile dysfunction.

OBJECTIVES: To characterize the effects of experimental hypertriglyceridemia on erectile function. METHODS: The daily water intake of 40 sexually mature male rats (groups II to V) was supplemented for 12 weeks with 10% fructose solution to induce hypertriglyceridemia. In addition, animals from three groups (III, IV, and V) were given through daily oral gavage metformin (group III), fenofibrate (group IV), and fish oil (group V) to estimate their therapeutic effects on fructose-induced metabolic alterations. Another group (I) of 10 rats served as controls. At 12 weeks, changes in sexual behavior and cavernous pressure response to nerve stimulation were correlated with serum triglyceride levels and response to preventive measures. RESULTS: After administration of 10% fructose, triglyceride levels increased fourfold to 1.79 +/- 0.31 mmol/L (mean +/- standard deviation) (group II). Coinciding with this elevation was a significant impairment of the copulatory pattern, with prolongation of mount (3.70 +/- 3.44 minutes), intromission (7.09 +/- 4.49 minutes), and ejaculatory latencies and reduced intracavernous pressure (27.56 +/- 2.04 mm Hg) response to nerve electrical stimulation. Whereas similar significant impairment was seen in group III, the other two groups (IV and V) showed beneficial effects of triglyceride reduction on these parameters. CONCLUSIONS: Our results provide the first evidence for an impact of triglycerides on erectile function. This detrimental effect is likely to be due to functional vascular and neuronal deficits related to hypertriglyceridemia.

Animals↗

PubMed2005

Effect of Tribulus terrestris on nicotinamide adenine dinucleotide phosphate-diaphorase activity and androgen receptors in rat brain.

Tribulus terrestris L. (Zygophyllaceae) have been used as an aphrodisiac both in the Indian and Chinese traditional systems of medicine. Administration of Tribulus terrestris extract (TT) increased sexual behaviour and intracavernous pressure both in normal and castrated rats and these effects were probably due to the androgen increasing property of TT. The objective of the present study is to evaluate the effect of TT on nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) activity and androgen receptor (AR) immunoreactivity in rat brain. Twenty-four adult male Sprague-Dawley rats were divided into two groups of twelve each. Group I was treated with distilled water and Group II was treated with TT at the dose of 5mg/kg body weight orally, once daily for 8 weeks. Following treatment transcardiac perfusion was done with Ringer lactate, 4% paraformaldehyde and 30% sucrose. The brain tissue was removed and sections of the paraventricular (PVN) area of hypothalamus were taken for NADPH-d and AR immunostaining. There was an increase in both NADPH-d (67%) and AR immunoreactivity (58%) in TT treated group and these results were statistically significant compared to the control. Chronic treatment of TT in rats increases the NADPH-d positive neurons and AR immunoreactivity in the PVN region. Androgens are known to increase both AR and NADPH-d positive neurons either directly or by its conversion to oestrogen. The mechanism for the observed increase in AR and NADPH-d positive neurons in the present study is probably due to the androgen increasing property of TT. The findings from the present study add further support to the aphrodisiac claims of TT.

Animals↗

PubMed2004

Pregnancy outcomes following pre- and post-implantation exposure of Sprague-Dawley rats to benzyl isothiocyanate.

The present investigation examines the outcomes of rats' pregnancy following pre- and post-implantation maternal exposure (orally) to benzyl isothiocyanate (BITC; 12.5, 25 and 50 mg/kg body weight). Three maternal deaths were recorded in the group of rats treated with 50 mg/kg BITC. Obvious signs of toxicity characterized by hypo-activity, perinasal staining, piloerection, hunched posture and decrease in body weights were observed in BITC-treated rats during the treatment periods. Dose-dependent increase in early fetal resorptions was seen in rats treated with BITC prior to implantation, but was not statistically significant. There were no significant differences in the number of implantation sites in treatment groups compared with the control. Similarly, there were no significant differences in the number of fetal resorptions, relative weights of maternal liver, kidney and spleen of rats in post-implantation treatment groups compared with the control. The differences in the number of viable fetuses in treatment groups compared with the control were also not significant. However, fetal weights in rats treated with 25 and 50 mg/kg BITC and placental weights in all the treatment groups were significantly lower than the control. In conclusion, at 12.5-50 mg/kg, BITC did not cause significant pre- and post-implantation fetal loss in pregnant rats. BITC-induced low fetal and placental weights could be of obstetrical importance, but at levels/doses that would provoke maternal toxicity.

Administration, Oral↗

PubMed2004

Estrogen and phytoestrogen predispose to erectile dysfunction: do ER-alpha and ER-beta in the cavernosum play a role?

OBJECTIVES: To investigate the functional changes in rabbit penile corpus cavernosum (CC) secondary to experimental hyperestrogenism and attempt to identify sites of immunoexpression for estrogen receptor subtypes alpha and beta (ER-alpha and ER-beta) in the CC. Although the role of testosterone in sexual function has been extensively studied in clinical settings and experimental animal models, the effect of hormonal modulation/imbalance arising from estrogenic excess has not been characterized. METHODS: Eighteen New Zealand white male rabbits (2.5-3.0 kg) were divided into control and two treatment groups. The two treatment groups were given orally 0.1 mg of estradiol valerate (estradiol group) or phytoestrogen, daidzein (phytoestrogen group) daily for 12 weeks. Blood and tissue samples were collected for hormone levels and in vitro pharmacologic studies. CC samples from untreated rabbits (n = 4) were cryosectioned and incubated with appropriate mouse monoclonal antibody for identification of ER-alpha and ER-beta. RESULTS: Through immunohistochemistry, color signals for nuclear ER-alpha and ER-beta receptors were localized within the CC. Chronic treatment with estradiol and phytoestrogen significantly reduced the systemic total testosterone levels. In organ bath experiments, relaxant responses to acetylcholine, nitroglycerin, and nitrergic transmission were significantly attenuated compared with the control response. With regard to the contractile effect, both types of estrogen treatments significantly potentiated norepinephrine-induced antierectile contraction of the CC. CONCLUSIONS: These results indicate that estradiol treatment and chronic exposure of phytoestrogen may cause receptor-mediated pathophysiologic changes in erectile function, leading to erectile dysfunction.

Acetylcholine↗

PubMed2004

Histaminergic effect of crude papaya latex on isolated guinea pig ileal strips.

In the present study, we investigated the effect of the crude latex of Carica papaya L. (CPX) on isolated guinea pig ileal strips. CPX (0.5-512 microg/ml) caused concentration-dependent contraction of ileal strips suspended in Tyrode solution. The concentration of atropine (0.69 microM) that significantly blocked the contractile effect of acetylcholine on the isolated guinea pig ileum showed no significant effect on CPX- and histamine-induced contractions of the ileal strips. Mepyramine (87.6 nM) significantly blocked the contractile effect of histamine and CPX on the ileum. The same concentration of mepyramine, however, had no significant effect on acetylcholine-induced contraction of the isolated ileal strips. Removal of Ca2+ from the bathing medium abolished ileal contractions induced by acetylcholine, histamine and CPX. All the test substances were able to provoke ileal contractions after replacement of the Ca(2+)-free solution with Tyrode solution. Furthermore, 10(-5) M of nifedipine, a Ca(2+)-entry antagonist, reversibly inhibited the contractile effect of all the test substances on the ileal strips. Results of this study together appear to show that CPX-induced contraction of the isolated guinea pig ileum is mediated via H1-receptors and dependent on extracellular Ca2+ influx.

Acetylcholine↗

PubMed2003

Oestrogen-mediated hormonal imbalance precipitates erectile dysfunction.

Declining testosterone (T) in an aging male offsets the equilibrium between androgen and oestrogen (oestradiol, E(2)) with a resultant increase in E(2)-T ratio. Similar functional hormone imbalance is existent in clinical states of hypogonadism and is likely to arise from exposure of males to environmental oestrogens. The pathophysiological significance of this derangement on erectile function, hitherto unknown, was estimated in sexually mature male rats following acute and chronic treatment with oestrogen. A total of 60 male Sprague-Dawley rats (200-250 g) were divided into control and two treatment groups, administered 0.01 and 0.1 mg of oestradiol through oral gavage daily for 1 week (n=30, acute study) and 12 weeks (n=30, long-term study), respectively. Sexual activity in the presence of hormonally primed female rats and intracavernous pressure (ICP) response to electrical stimulation estimated treatment-induced changes, which were correlated with hormone levels and penile morphology at 12 weeks. Following two to five-fold elevation in serum E(2) levels (and simultaneous reduction in testosterone), there was a significant prolongation of mount, intromission, ejaculation latencies and some decrease in frequencies. The ICP response to nerve stimulation was also impaired in all the treated groups. Histologically, trichrome staining highlighted the cavernosal connective tissue hyperplasia in the long-term study groups. Results of this investigation indicate that oestradiol causes pathophysiological changes in erectile function. These observations provide an indirect evidence for the possible sexual health hazards in man upon inadvertent exposure to environmental oestrogens, ageing and derangement of E(2)-T ratio.

Administration, Oral↗

PubMed2003

Oestrogen-androgen crosstalk in the pathophysiology of erectile dysfunction.

Ageing in man is associated with a decline in testosterone following changes in the hypothalamo-pituitary-testicular axis. This may offset the physiologic equilibrium between oestrogen and androgen and at some point when the ratio of free testosterone to oestradiol reaches a critical level, the oestrogenic gonadotropin suppressive effect predominates with decreased release of FSH and LH. Adding to this endocrinal complexity is the continued peripheral conversion to oestradiol through aromatisation. Although the androgen deficiency is not the sole cause for impotence in the elderly, there is a gradual decrease in nocturnal penile tumescence (NPT) and spontaneous morning erections with ageing. Despite the age related increase in oestrogen levels, the information on the pathophysiological role of the "female hormone" in erectile dysfunction has been scanty. Together with our identification of oestrogen receptors within the penile cavernosum, we have delineated dysfunctional changes on male erection mediated by oestradiol. These findings parallel the recent concerns over environmental oestrogens on fertility declines in young men. Oestrogenic activity is also present in plants and thereby in human diet. These phytoestrogens are structurally and functionally similar to oestradiol and more potent than the environmental oestrogenic chemicals such as organochlorine and phenolic compounds. Thus in the light of growing concerns of possible compromising effects on sexuality by endogenous and environmental oestrogens, we are faced with the scientific need to delineate their role on the mechanism of male erectile pathway in health and disease for clinical correlates and prognostics.

Aged↗

PubMed2002

Aphrodisiac properties of Tribulus Terrestris extract (Protodioscin) in normal and castrated rats.

Tribulus terrestris (TT) has long been used in the traditional Chinese and Indian systems of medicine for the treatment of various ailments and is popularly claimed to improve sexual functions in man. Sexual behaviour and intracavernous pressure (ICP) were studied in both normal and castrated rats to further understand the role of TT containing protodioscin (PTN) as an aphrodisiac. Adult Sprague-Dawley rats were divided into five groups of 8 each that included distilled water treated (normal and castrated), testosterone treated (normal and castrated, 10 mg/kg body weight, subcutaneously, bi-weekly) and TT treated (castrated, 5 mg/kg body weight, orally once daily). Decreases in body weight, prostate weight and ICP were observed among the castrated groups of rats compared to the intact group. There was an overall reduction in the sexual behaviour parameters in the castrated groups of rats as reflected by decrease in mount and intromission frequencies (MF and IF) and increase in mount, intromission, ejaculation latencies (ML, IL, EL) as well as post-ejaculatory interval (PEI). Compared to the castrated control, treatment of castrated rats (with either testosterone or TT extract) showed increase in prostate weight and ICP that were statistically significant. There was also a mild to moderate improvement of the sexual behaviour parameters as evidenced by increase in MF and IF; decrease in ML, IL and PEI. These results were statistically significant. It is concluded that TT extract appears to possess aphrodisiac activity probably due to androgen increasing property of TT (observed in our earlier study on primates).

Androgens↗

PubMed2002

The effects of 5HT(1) agonists on erection in rats in vivo and rabbit corpus cavernosum in vitro.

We have examined the effects of the selective 5-HT(1a) and 5-HT(1b) agonists 8-hydroxy-2-(di-n-propylamino)tetralin (8-OHDPAT) and 7-trifluoromethyl-4-(4-methyl-1-piperazinyl)-pyrrolo[1,2-a]quinoxaline (CGS12066b), respectively on erection in rats in vivo and rabbit corpus cavernosum in vitro. Apomorphine (0.1 mg/kg) induced 3.1+/-0.4 erections in vehicle-pretreated animals. At the highest doses tested 8-OHDPAT (0.4-0.64 mg/kg) and CGS12066b (1.0-10.0 mg/kg) significantly reduced apomorphine erection to 0.9+/-0.3 erections and 0.5+/-0.2 erections respectively. The nonselective 5-HT agonist metachlorophenylpiperazine (m-CPP; 0.1 mg/kg) elicited characteristic increases in cavernous nerve activity (CNA) and intracavernous pressure responses (ICP) in anesthetized rats. 8-OHDPAT (0.64 mg/kg) and CGS12066b (1.0 mg/kg) failed to elicit CNA or ICP responses. CGS12066b reduced ICP responses resulting from the direct stimulation of the cavernous nerve whereas 8-OHDPAT did not. CGS12066b reduced the CNA and ICP responses to m-CPP administration whereas 8-OHDPAT potentiated m-CPP induced CNA and ICP responses. In isolated rabbit corpus cavernosum (CC) 8-OHDPAT and CGS12066b both failed to alter noradrenergic induced contraction and non-adrenergic non-cholinergic relaxation. Our results indicate that selective 5-HT(1a) and 5-HT(1b) agonists have different effects in different models of erection.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed2002

Metachlorophenylpiperazine (m-CPP) induced intracavernous pressure responses in anaesthetized rats.

Here we have recorded the effects of metachlorophenylpiperazine (m-CPP) on intracavernous pressure (ICP) in anesthetized rats pretreated with various pharmacological agents in an attempt to determine the mechanism and relevance of the m-CPP induced ICP response to other models of erection. m-CPP elicited consistent and significantly greater increases in ICP (71.5+/-6.6 mmHg) compared with the mixed 5-HT(2a/2c) agonists trifluoromethylphenylpiperazine (3.4+/-1.3 mmHg) and quipazine (10.9+/-1.8 mmHg). Blockade of 5-HT(2a) receptors with ketanserin failed to unmask any stimulatory effect of quipazine (7.2+/-1.0 mmHg). m-CPP induced ICP responses (71+/-7.0 mmHg) were unaffected in the presence of mianserin (63+/-5 mmHg) and ketanserin (51+/-12 mmHg). Spiperone significantly reduced the m-CPP induced increase in ICP (8.0+/-1.0 mmHg). Naloxone, yohimbine and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OHDPAT) failed to elicit increases in ICP on their own. All three drugs significantly reduced the latency to the first m-CPP induced ICP response compared to saline. Yohimbine increased the duration of m-CPP induced ICP responses whereas 8-OHDPAT increased the mean number of m-CPP induced ICP responses compared to saline. The effects of m-CPP on ICP in anesthetized rats may not be mediated by 5-HT(2c) receptors and appears to be similar to erection in copula, but not erection elicited by other drugs or penile sheath retraction.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed2001

Oxytocics reverse the tocolytic effect of glyceryl trinitrate on the human uterus.

OBJECTIVES: To investigate the effect of glyceryl trinitrate on isolated human pregnant uterine strips and whether the uterine relaxation induced by glyceryl trinitrate could be reversed by oxytocics used in current clinical practice. DESIGN: In vitro pharmacological study. SETTING: Department of Obstetrics & Gynaecology, National University of Singapore, National University Hospital. PARTICIPANTS: Eighteen women who delivered by caesarean section at term. METHODS: Myometrial strips were preloaded with an initial tension of 1.5g in organ baths containing Krebs-Henseleit solution which was aerated with oxygen in 5% carbon dioxide and maintained at 37 degrees C, pH 7.4. The effect of glyceryl trinitrate was studied in strips displaying regular spontaneous contractions. The ability of oxytocin, ergometrine or prostaglandin F2alpha to stimulate uterine contractions was assessed in strips where uterine activity was significantly inhibited by glyceryl trinitrate. RESULTS: Glyceryl trinitrate reduced the amplitude and frequency of spontaneous uterine contractions in a concentration-dependent manner, although the sensitivity of the myometrial strips varied considerably from one specimen to another. The concentration of glyceryl trinitrate producing complete inhibition of myometrial contractions ranged from 44-705 microM. In the presence of glyceryl trinitrate which markedly depressed spontaneous contractions, oxytocin (20 mU/mL), ergometrine (6.15 microM) and prostaglandin F2alpha (6.15 microM) were capable of reversing the uterine activity to either higher than or the untreated level of contractility. CONCLUSIONS: This study demonstrates that glyceryl trinitrate is a potent uterine relaxant in vitro and that the tocolytic effect could be reversed with ease by oxytocics.

Dinoprost↗

PubMed2000

Proerectile pharmacological effects of Tribulus terrestris extract on the rabbit corpus cavernosum.

INTRODUCTION: The objective of the present study was to investigate the effect of oral treatment of Tribulus terrestris (TT) extract on the isolated corpus cavernosal tissue of New Zealand white (NZW) rabbits and to determine the mechanism by which protodioscin (PTN), a constituent of the TT, exerts its pharmacological effects. MATERIALS AND METHODS: Twenty-four NZW rabbits were randomly assigned to 4 experimental groups of 6 each. Group I served as control. Groups II to IV were treated with the extract at different dose levels, i.e. 2.5 mg/kg, 5 mg/kg and 10 mg/kg body weight, respectively. The TT extract was administered orally, once daily, for a period of 8 weeks. The rabbits were then sacrificed and their penile tissue isolated to evaluate the responses to both contracting and relaxing pharmacological agents and electrical field stimulation (EFS). RESULTS: PTN on its own had no effect on the isolated corpus cavernosal strips. The relaxant responses to EFS, acetylcholine and nitroglycerin in noradrenaline precontracted tissues from treated groups showed an increase in relaxation of a concentration dependent nature compared to that of the tissues from control group. However, the contractile, anti-erectile response of corpus cavernosal tissue to noradrenaline and histamine showed no significant change between the treatment and the control groups. CONCLUSIONS: The relaxant responses to acetylcholine, nitroglycerin and EFS by more than 10%, 24% and 10% respectively compared to their control values and the lack of such effect on the contractile response to noradrenaline and histamine indicate that PTN has a proerectile activity. The enhanced relaxant effect observed is probably due to increase in the release of nitric oxide from the endothelium and nitrergic nerve endings, which may account for its claims as an aphrodisiac. However, further study is needed to clarify the precise mechanism of its action.

Animals↗

PubMed2000

Physiological significance of nitrergic transmission in human penile erection.

The corpora cavernosa (CC) muscles of the human penis and their structural arrangements are essential for the physiology of erection. Contraction of this muscle causes detumescence, and relaxation, tumescence. The motor excitatory neurotransmission is adrenergic, acting through the alpha adrenoceptors. Continuous adrenergic transmitter (noradrenaline) release is necessary for the maintenance of non-erectile (contractile) state of the penis. The inhibitory neurotransmitter that relaxes CC muscle to produce erection is nitrergic i.e., the chemical messenger being nitric oxide (NO). The latter can also be released from cavernous endothelium. Presence of NO increases intracellular cGMP through activation of the enzyme guanylate cyclase. This causes relaxation of CC muscle. Phosphodiesterase type 5 (PDE5) is responsible for the degradation of cGMP and regulation of CC muscle tone. Specific PDE inhibitors such as sildenafil enhance the intracellular cGMP to improve erection. Increase in intracellular cAMP can also bring about pharmacological erection in man (e.g. PGE1, papaverine and histamine). Inhibition of excessive adrenergic tone with appropriate alpha-adrenergic blocking agents (e.g. phentolamine) can also contribute to the onset of pharmacological erection.

Humans↗

PubMed2000

Transurethral alprostadil for the treatment of erectile dysfunction: results of a multicentre trial.

INTRODUCTION: The incidence of erectile dysfunction (ED) has been shown to increase significantly in Singaporean male population. Thus, this prospective study (no controls) assessed the clinical efficacy and safety of a medicated urethral system for erection (MUSE) in Singaporean male patients with a known history of ED. SUBJECTS AND METHOD: Eighty-six men with a mean age of 55.7 years with differential causes of ED were administered with MUSE in the clinic with a titration adjustment of 4 possible dose regimes (125, 250, 500 and 1000 mcg) till efficacy is achieved. Subsequently, patients were subjected to home treatment for a duration of 3 months. RESULTS: Sixty per cent of inclinic patients exhibited good responses and were given MUSE for home treatment. The efficacy rate for home treatment was 86%. Overall, the patients (n = 86) had a 51.2% success rate in achieving satisfactory sexual intercourse. Diabetic and psychogenic patients were noted to respond well to MUSE. No severe adverse events were found in this study. CONCLUSION: MUSE showed to be a safe, less invasive, well-tolerated and efficient alternative treatment for ED in Singaporean men.

Adult↗

PubMed1999

Sexual dysfunction related to antihypertensive agents: results from the animal model.

The present investigation elucidates the deleterious effects of three prototypical antihypertensive drugs namely, propranolol, clonidine and captopril on the erectile physiology. In order to delineate the direct drug effects from vascular insufficiency inherent in hypertensive states, the study was conducted on a normotensive animal model. The adverse effects of these drugs were estimated as changes in sexual behaviour and intracavernous pressure response of electrical stimulation in the treated rats compared to normal age-matched controls (n = 10, each group). Copulation studies indicated significant impairment of sexual function in the groups on propranolol and clonidine. The cavernous pressure response to nerve stimulation at the end of sixteen weeks further reinforced the gross compromise on sexual function in these two treated groups. In contrast, the captopril administration produced only marginal alterations to the responses recorded. The results from this study clearly indicate that propranolol and clonidine interfere with sexual behaviour and nerve mediated response to erection whereas captopril which is devoid of significant effects on these parameters, may be a better therapeutic option.

Animals↗

PubMed1999

Elevated low-density lipoprotein cholesterol (LDL-C) enhances pro-erectile neurotransmission in the corpus cavernosum.

Hypercholesterolaemia is thought to foster atherosclerosis and impotence through its effects on vascular endothelium. In this study, we investigated the pharmacological changes in rabbit corpus cavernosum (CC) secondary to incubation with lysolecithin and hypercholesterolaemia. A daily egg yolk dietary supplement induced gross hypercholesterolaemia in our rabbits. Group A of test animals (n-12) was fed with the yolk content of single egg and group B (n-6), that from two eggs for eight weeks. Serum level estimation revealed a progressive elevation of cholesterol to 15 and 30 times respectively, in the two treated groups as compared to values in the control group (n-6). Early histological manifestations of atherosclerosis were perceived as fat cell lesions in the cavernosum of treated animals. In vitro pharmacological studies on CC strips from both groups of test animals demonstrated a profound accentuation of the contractile responses to noradrenaline and histamine and attenuation of relaxant response to acetylcholine. However, in contrast to single-egg treated group, which demonstrated a reduction in the relaxant response to electrical field stimulation (EFS), there was a marked and statistically significant potentiation of this nitrergic transmission, in the two-eggs group. Prior incubation of CC strips of normolipidaemic rabbits (n-7) with lysolecithin, reproduced similar exaggerated response to EFS. Therefore, from the results of our study, it is concluded that oxidised LDL or its major amphiphile lysolecithin, at some critical level or beyond, may be capable of reverting at least some of the adverse effects of hypercholesterolaemia on erectile function, through its mediating effect on nitrergic transmission.

Acetylcholine↗

PubMed1999

5-HT4 receptors in isolated human corpus cavernosum?

The novel serotonin subtype-4 (5-HT4) receptor agonist, SC53116 (SC), produced a limited relaxation of noradrenaline (NA) pre-contracted human corpus cavernosum (CC) smooth muscle in vitro. This effect was not significantly attenuated by the 5-HT4 antagonist SDZ250557 (SDZ). In the presence of (+/-) pindolol (1 microM) and methysergide (1 microM), employed to mask 5-HT1 and beta-adrenergic, and 5-HT2 receptors respectively, SC failed to relax NA pre-contracted CC strips to a greater extent than saline. Functional cAMP dependent relaxation pathways were demonstrated by a significant reduction in NA induced tone by prostaglandin E1 (PGE1) and isopropylnoradrenaline (IPNA), the action of the latter compound was effectively eliminated in the presence of (+/-) pindolol. Relaxation of NA induced tone caused by the nitric oxide donor nitro-glycerine (NTG) was significant and similar in the absence and presence of the 5-HT and beta-adrenergic antagonists. The results of this present study indicate that human corporal smooth muscle does not contain 5-HT4 receptors and that, although compounds like SC act to relax non-vascular smooth muscle via cAMP dependent mechanisms, 5-HT4 receptor agonists may be expected to be of limited utility in triggering cAMP dependent relaxation responses in human CC.

4-Aminobenzoic Acid↗

PubMed1997

Effects of feeding egg yolk on the serum lipid levels in rabbits.

Healthy, nonobese, young rabbits developed hypercholesterolemia following daily intake of fresh egg yolk for 8 weeks. On a quantitative basis, this diet had a profound effect on serum cholesterol level which rose to 15 or 30 times the baseline value depending on whether the test group consumed the yolk content of one or two eggs during the study. Similar drastic changes observed in low density lipoprotein cholesterol levels in these test animals make this a useful method for defining the early pathological changes of atherosclerosis in man. In addition, the present study provides direct evidence of the deleterious effect of hen's egg yolk on the serum cholesterol level in an appropriate and easily reproducible animal model.

Animals↗