STUDY OF THE EFFECTS OF BETA-MYRCENE ON RAT FERTILITY AND GENERAL REPRODUCTIVE-PERFORMANCE

beta-Myrcene (MYR) is a monoterpene found in the oils of a variety of aromatic plants including lemongrass, verbena, hop, bay, and others. M YR and essential oils containing this terpenoid compound are used in c osmetics, household products, and as flavoring food additives, This st udy was undertaken to investigate the effects of MYR on fertility and general reproductive performance in the rat. MYR(0, 100, 300 and 500 m g/kg) in peanut oil was given by gavage to male Wistar rats (15 per do se group) for 91 days prior to mating and during the mating period, as well as to females (45 per dose group) continuously for 21 days befor e mating, during mating and pregnancy, and throughout the period of la ctation up to postnatal day 21. On day 21 of pregnancy one-third of th e females of each group were submitted to cesarean section. Resorption , implantation, as well as dead and live fetuses were counted; All fet uses were examined for external malformations, weighed, and cleared an d stained with Alizarin Red S for skeleton evaluation. The remaining d ams were allowed to give birth to their offspring. The progeny was exa mined at birth and subsequently up to postnatal day 21. Mortality, wei ght gain and physical signs of postnatal development were evaluated. E xcept for an increase in liver and kidney weights, no other sign of to xicity was noted in male arid female rats exposed to MYR. MYR did not affect the mating index (proportion of females impregnated by males) o r the pregnancy index (ratio of pregnant to sperm-positive females). N o sign Of maternal toxicity and no increase in externally visible malf ormations were observed at any dose level, Only at the highest dose te sted (500 mg/kg) did MYR induce an increase in the resorption rate and a higher frequency of fetal skeleton anomalies; No adverse effect of MYR on postnatal weight gain was noted but days of appearance of prima ry coat, incisor eruption and eye opening were slightly delayed in the exposed offspring. On the basis of the data presented in this paper t he no-observed-adverse-effect level (NOAEL) for toxic effects on ferti lity and general reproductive performance can be set at 300 mg of beta -myrcene/kg body weight by the oral route.