Androgenic effect of honeybee drone milk in castrated rats: roles of methyl palmitate and methyl oleate.

ETHNOPHARMACOLOGICAL RELEVANCE: Numerous honeybee (Apis mellifera) products have been used in traditional medicine to treat infertility and to increase vitality in both men and women. Drone milk (DM) is a relatively little-known honeybee product with a putative sexual hormone effect. The oestrogenic effect of a fraction of DM has recently been reported in rats. However, no information is available on the androgenic effects of DM. The purpose of the present study was to determine the androgen-like effect of DM in male rats and to identify effective compounds. MATERIALS AND METHODS: A modified Hershberger assay was used to investigate the androgenic effect of crude DM, and the plasma level of testosterone was measured. The prostatic mRNA and protein expression of Spot14-like androgen-inducible protein (SLAP) were also examined with real-time PCR and Western blot techniques. GC-MS and NMR spectroscopic investigations were performed to identify the active components gained by bioactivity-guided fractionation. RESULTS: The crude DM increased the relative weights of the androgen-dependent organs and the plasma testosterone level in castrated rats and these actions were flutamide-sensitive. DM increased the tissue mRNA and protein level of SLAP, providing further evidence of its androgen-like character. After bioactivity-guided fractionation, two fatty acid esters, methyl palmitate (MP) and methyl oleate (MO), were identified as active compounds. MP alone showed an androgenic effect, whereas MO increased the weight of androgen-sensitive tissues and the plasma testosterone level only in combination. CONCLUSION: The experimental data of DM and its active compounds (MO and MP) show androgenic activity confirming the traditional usage of DM. DM or MP or/and MO treatments may project a natural mode for the therapy of male infertility.

Nociceptin inhibits uterine contractions in term-pregnant rats by signaling through multiple pathways.

The actions of the endogenous peptide nociceptin (PNOC; previously abbreviated as N/OFQ) on the myometrium have not been investigated previously. Our aim was to study the presence and functional role of PNOC in the modulation of uterine contractility in pregnant rats at term. The presence of PNOC and its receptors (OPRL1; previously called NOP) in the uterus were detected by radioimmunoassay and radioligand-binding experiments. The PNOC-stimulated G protein activation was assessed by a [(35)S]GTPgammaS-binding technique. The effects of PNOC in uterine rings precontracted with KCl or oxytocin were also tested in vitro. Uterine levels of cAMP were measured by enzyme immunoassay. The K(+) channel blockers tetraethylammonium and paxilline were used to study the role of K(+) channels in mediating the uterine effects of PNOC. Both PNOC and OPRL1 were present in the uterus. PNOC revealed a maximum contraction inhibition of approximately 30%, which was increased to 40% by naloxone. Naloxone and pertussis toxin significantly attenuated the G protein-stimulating effect of PNOC. The uterine cAMP levels were elevated by PNOC and naloxone and after preincubation with pertussis toxin. Tetraethylammonium and paxilline reduced the contraction-inhibiting effect of PNOC and naloxone to approximately 10% and 15%, respectively. We presume that PNOC plays a role in regulating uterine contractility at term. Its effect is mediated partly by stimulatory heterotrimeric G (G(s)) proteins coupled to OPRL1 receptors and elevated cAMP levels, and also by Ca(2+)-dependent K(+) channels. Our results demonstrate a novel action and signaling pathway for PNOC that might be a potential drug target.