Sodium nitroprusside impairs sexual competence of male rats.

Recently, sodium nitroprusside (SNP), a potent nitric oxide (NO) donor and a clinically used antihypertensive, has been introduced as a penile self-injection medical therapy for erectile dysfunction. However, it is known that many antihypertensives impairs sexual competence; NO regulates sexual competence and NO is cytostatic and cytotoxic for human sperm. Thus, a possibility exists that SNP may impair male reproductive competence. Testing this aspect is the aim of this study. This was assessed in male rats (using three i.p. doses: 60, 30 or 20 microg/kg) using noncompetitive copulation tests. The results show that the highest dose of SNP was toxic and caused rapid mortality of treated rats (within 30 min). The mid and low doses of SNP reversibly impaired several parameters of sexual competence in a dose-related fashion: sexual arousability, libido and sexual vigour. Some parameters of sexual behaviour remained unaltered: sexual motivation and intromission ratio, whilst one parameter was improved: sexual performance. In complete contrast, the ejaculatory competence and fertility remained unchanged. The SNP-induced impairments in sexual competence may be attributable to lowered testosterone levels and sedation mediated via its specific action and/or side effect. Further, this impairment of sexual function was not due to general toxicity, inhibition of penile sensitivity, penile erection or analgesic activity. It is concluded that SNP impairs male sexual competence, at least, in rats although it promotes penile erection.

Anti-inflammatory and analgesic activities of mature fresh leaves of Vitex negundo.

This study confirmed the oral anti-inflammatory, analgesic and antihistamine properties of mature fresh leaves (MFL) of Vitex negundo L. (Verbenaceae) claimed in the Ayurveda medicine by orally treating a water extract of the leaves to rats. The early phase (2h) of carrageenan-induced rat paw oedema was significantly (P<0.01) suppressed in an inversely does-dependent (r(2)=1, P<0.01) manner by MFL. The EC(50) was 2g/kg of MFL. In the formaldehyde-induced rat paw oedema test, the 2.5 and 5g/kg leaves significantly (P<0.05) suppressed the inflammation on days 4-6 of the test. In the hot plate test, 2.5 and 5g/kg of MFL showed a significant (P<0.05) and directly dose-dependent analgesic activity at 1h of treatment while the activity was absent in the tail flick test in rats. The EC(50) for the analgesic activity was 4.1g/kg. In the formalin test, 1.25, 2.5 and 5g/kg of MFL significantly (P<0.05) suppressed the pain in both the phases of the test like aspirin. The leaves showed an inversely dose-dependent in vivo antihistamine and in vitro prostaglandin (PG) synthesis inhibition, membrane stabilising and antioxidant activities. Naloxone did not abolish the analgesic activity in the hot plate test. A 5g/kg of MFL did not impair muscle strength and co-ordination and did not induce sedation. The treatment of 5g/kg of MFL did not show signs of acute toxicity or stress. Fourteen-day oral treatment of 5g/kg of MFL significantly increased the serum activity of AST. Flowering of the tree did not abolish the analgesic and anti-inflammatory activities of the leaves. These observations revealed that the fresh leaves of Vitex negundo have anti-inflammatory and pain suppressing activities possibly mediated via PG synthesis inhibition, antihistamine, membrane stabilising and antioxidant activities. The antihistamine activity can produce the anti-itching effect claimed in Ayurveda medicine.

Anti-inflammatory and analgesic activity in the polyherbal formulation Maharasnadhi Quathar.

Maharasnadhi Quathar (MRQ) is a polyherbal preparation recommended by Ayurvedic medical practitioners for treatment of arthritic conditions. An investigation has been carried out with rats and human rheumatoid arthritis (RA) patients, to determine the anti-inflammatory and analgesic potential of MRQ. Results obtained demonstrate that MRQ can significantly and dose-dependently inhibit carrageenan-induced rat paw oedema (the inhibition at 3h was greater than at 1h after induction of oedema). MRQ could also increase the reaction time of rats in the hot-plate test (by 57% after the first hour of treatment), although it had no effect on the reaction time in the tail-flick test, indicating that MRQ possesses analgesic activity that is probably mediated via a supra-spinal effect.MRQ also exerted a dose-dependent (a) protective effect on heat-induced erythrocyte lysis, and (b) inhibition of 5-lipoxygenase activity. In RA patients, after 3 months of MRQ treatment, there was a marked improvement in the pain and inflammation experienced by the patients as well as in the mobility of the affected joints. From the overall results obtained, it may be concluded that MRQ possesses significant anti-inflammatory and analgesic activities. Alteration in synthesis of prostaglandins and leukotrienes, membrane stabilization and anti-oxidant activity are some of the possible mechanisms through which MRQ mediates its anti-arthritic effects.

L-arginine, the substrate of nitric oxide synthase, inhibits fertility of male rats.

AIM: To examine the effect of L-arginine, the substrate of nitric oxide (NO) synthase, on reproductive function of male rats. METHODS: Male rats were gavaged with either L-arginine (100 or 200 mg x kg(-1) x d(-1)), D-arginine (200 mg x kg(-1) x d(-1)) or vehicle (0.9% NaCl) for seven consecutive days. Their sexual behaviour and fertility were evaluated using receptive females. RESULTS: L-arginine (200 mg/kg) had no significant effect on sexual competence (in terms of sexual arousal, libido, sexual vigour and sexual performance). In mating experiments, the higher dose of L-arginine effectively and reversibly inhibited fertility, whilst the lower dose and the inactive stereoisomer D-arginine had no significant effect. The antifertility effect caused by L-arginine was due to a profound elevation in the preimplantation loss mediated possibly by impairment in epididymal sperm maturation, hyperactivated sperm motility and sperm capacitation. CONCLUSION: Elevated NO production may be detrimental to male fertility.

Reduction in libido and fertility of male rats by administration of the nitric oxide (NO) synthase inhibitor N-nitro-L-arginine methyl ester.

The role of nitric oxide (NO) in libido and fertility of male rats was investigated by administration of the NO synthase inhibitor N-nitro-L-arginine methyl ester (L-NAME) (25 or 50 mg/kg/day). L-NAME caused marked reduction of precoital sexual behaviour, and a failure of most rats to mount or ejaculate during the test interval. In most matings that were successful, recovered spermatozoa were present in normal numbers. In mating experiments, L-NAME profoundly reduced the fertility of male rats. In those animals that did succeed in mating, the quantal pregnancy and the number of implants were reduced. After cessation of treatment with L-NAME, the fertility parameters returned close to normal. The inactive stereoisomer, D-NAME, caused none of the above effects when administered to rats. The results suggest that NO is essential for the expression of normal libido and fertility in male rats. It is likely that NO is required both in the male reproductive tract and in the brain.

Effects of Terminalia catappa seeds on sexual behaviour and fertility of male rats.

AIM: To evaluate the aphrodisiac potential of Tenminalia catappa Linn. seeds using a suspension of its kernel (SS) in 1% methyl cellulose in rats. METHODS: Male rats were orally treated with 1,500 mg/kg or 3,000 mg/kg SS or vehicle, and their sexual behaviour was monitored 3 h later using a receptive female. Another group of rats was orally treated with either 3,000 mg/kg SS or vehicle for 7 consecutive days. Their sexual behaviour and fertility were evaluated on days 1, 4 and 7 of treatment and day 7 post-treatment by pairing overnight with a pro-oestrous female. RESULTS: The 1,500 mg/kg dose, had a marked aphrodisiac action (prolongation of ejaculation latency) but no effect on libido (% mounting, % intromission and % ejaculation), sexual vigour (mounting-and-intromission frequency), or sexual performance (intercopulatory interval). In contrast, the higher dose (3,000 mg/kg) reversibly inhibited all the parameters of sexual behaviour other than mounting-and-intromission frequency and copulatory efficiency. The effects of high dose SS were not due to general toxicity, liver toxicity, haemotoxicity, stress, muscle deficiency, muscle incoordination, analgesia, hypoglycaemia or reduction in blood testosterone level. They were due to marked sedation. CONCLUSION: The kernel of T. catappa seeds has aphrodisiac activity and may be useful in the treatment of certain forms of sexual inadequacies, such as premature ejaculation.

Characterization of a cDNA encoding a novel heat-shock protein that binds to calmodulin.

A cDNA clone (pTCB48) encoding a calmodulin-binding protein was isolated by screening a lambda ZAPII cDNA expression library constructed from cell cultures of heat-shocked tobacco (Nicotiana tabacum L. cv Wisconsin-38) with metabolically labeled [35S]calmodulin. Calmodulin gel overlay analysis indicated that pTCB48 generated major peptides of 53, 36, and 22 kD and two minor peptides of 37 and 16 kD that bound calmodulin in a Ca(2+)-dependent manner. Deletion analysis of pTCB48 indicated that these and the minor calmodulin-binding proteins resulted from the insert. A probe made from the cDNA insert recognized two bands with sizes of 2.1 and 1.8 kb on northern blot analysis. Both species of RNAs were undetectable in the control and were induced after 15 min of heat-shock treatment at 38 degrees C. The intensity of the two bands reached maximum after 1.5 h of heat-shock treatment. The cDNA clone was not full length; however, the complete sequence was determined by 5' rapid amplification of cDNA ends using nested antisense primers. The full-length cDNA contains 1648 bp and a single open reading frame of 1347 bp and is expected to encode a protein of approximately 50 kD. No significant homology with other reported genes and proteins was found. Structural predictions, deletion analysis, and gel overlay analysis suggested that the calmodulin-binding domain was a basic amphiphilic alpha-helix near the C terminus of the protein. The strong induction of the mRNA for this protein suggests a role for Ca2+/calmodulin-mediated process in the heat-shock response.