Sex differences

Sex differences have been demonstrated in the toxicity of phosphorothionate pesticides to rats in vivo and in the oxidative capacity of liver slices from male and female rats in vitro. In studying the influence of various factors on the activation of azinphos-methyl and O-ethyl-O-phenyl-D-p-nitrophenylphos-phorothionate (EPN), the livers of male rats were found to be 2-3 times more active than those of females in converting these compounds to their oxo-analogues [47]. In young animals up to the age of 30 days, no difference is evident between males and females, but after 30 days the activity of the male liver rises while that of the female liver remains constant. Castration or administration of diethylstilboestrol prevents this rise in males, while admini- 

Carcinogenic hydrocarbons have been reported to increase the activity of this oxidising enzyme system in immature males, adult females and partially hepatectomized adult males [47]. This involves the synthesis of new enzyme protein which may be prevented by ethionine, a competitive antagonist to the incorporation of methionine into new protein [48]. The microsomal enzyme inhibitor SKF 525A similarly prevents oxidation of the phosphoro-thionates, so reducing their toxicity [47], Similar observations on the influence of sex hormones, age and microsomal enzyme inducers on the toxicity of schradan [49, 50], parathion [51, 52], fenitrothion [53], EPN. 0-(4-methyl-7-hydroxycoumarin)-0,( -diethylphosphorothionate (E838) [51] and 0,0-diethyl-0-(3-methyl-4-methylthiophenyl)phosphorothionate (DMP) [54] in rats have been reported. 

Keeper substances in a scent secretion, and/or the nature of the substrate such as rock, wood or soil, impart longevity to a scent mark. In our own studies, scent marks of captive pronghorn, A. americana, were still noticeable to the human nose 4 months after all animals had been removed from a pen. Similarly, scent marks of the aardwolf, Proteks cristatus, last for up to 6 months (Apps etal, 1989). 2-Phenoxyethanol in the secretions from the chin gland of the rabbit is typical in dominant animals, serving as a fixative to extend the life of the signal (Hayes etal, 2001). 

Some male-specific compounds have been identified in mammalian secretions that may have a role in communication (Table 2.2) 

The anal gland secretion of beaver, C. canadensis, differs between the sexes (Gr0nneberg, 1978-79). The male grey duiker, Sylvicapra grimmia, has more 2-heptanone and 2-nonadecanone in its preorbital secretion than the female. Two thiazoles (2-isobutyl-1,3-thiazole and 2-isobutyl-4,5-dihydro-l,3-thiazole) and an epoxy ketone (3,4-epoxy-2-dodecanone) are also more abundant in the male s secretion. Correlated with these chemical differences is the fact that only males scent mark with the preorbital gland (Burger etal., 1990). 

In European moles, Talpa europaea, a series of carboxylic acids dominates the anal gland secretion of both adult males and anestrous females. These acids disappear in proestrous and estrous females but are present again in pregnant and lactating females. The acids are also absent in juveniles. The anal scent appears to constitute a keep out signal, and its absence in estrous females permits mating (KhazenehdarietaZ., 1996). 

Bear Sus scrofa 16-Androstenes Saliva Melrose etal., 1971 

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Bell R, Havlicek P L, Roncek D W Sex differences in the use of alcohol and tranquilizers testing a role convergence hypothesis. Am J Drug Alcohol Abuse 10 551—561, 1984... 

Wolfe, M.S., Klein, L. 1996 Sex differences in absolute rates of bone resorption in young rats appendicular versus axial bones. Calcified Tissue International 59 51-57. 

The relative rates of activation and detoxification of methyl paraoxon within the liver determine whether net activation or detoxification will occur (Sultatos 1987). Sex-differences have been observed in acute... 

Sex differences in uptake and metabolism of trichloroethylene have been seen in both humans and animals (see Section 2.8). Studies with male and female rats given various levels of testosterone have implicated this hormone in determining the degree of dermal penetration of trichloroethylene (McCormick and Abdel-Rahman 1991). The mechanism behind this effect is still unclear. 

Sex differences in the urinary excretion of metabolites of trichloroethylene have been reported (Inoue et al. 1989 Nomiyama and Nomiyama 1971). In trichloroethylene-exposed workers, urinary levels of trichloro compounds and trichloroethanol were significantly higher in men than in women, while urinary levels of TCA did not differ between the two sexes (Inoue et al. 1989). However, it was reported that excretion of TCA in urine was greater in women than in men within 24 hours of exposure (Nomiyama and Nomiyama 1971). 

The use of the methods for monitoring metabolites of trichloroethylene in blood and urine is, however, rather limited since the levels of TCA in urine have been found to vary widely, even among individuals with equal exposure (Vesterberg and Astrand 1976). Moreover, exposure to other chlorinated hydrocarbons such as tetrachloroethane, tetrachloroethylene, and 1,1,1-trichloroethane would also be reflected in an increase in urinary excretion of TCA. In addition, there may be sex differences regarding the excretion of trichloroethylene metabolites in urine since one experiment shows that men secrete more trichloroethanol than women (Inoue et al. 1989). The use of the level of trichloroethylene adduction to blood proteins as a quantitative measure of exposure is also possible, although obtaining accurate results may be complicated by the fact that several metabolites of trichloroethylene may also form adducts (Stevens et al. 1992). 

Nomiyama K, Nomiyama H. 1971. Metabolism of trichloroethylene in humans Sex difference in urinary excretion of trichloroacetic acid and trichloroethanol. Int Arch Arbeitsmed 28 37-48. 

Another intriguing observation is that the female sex-hormone 17/i-estradiol (28) could dramatically potentiate capsaicin responses, whereas the male hormone testosterone had marginal inhibitory activity. Sex differences in pain responses have long been known, with women being more sensitive to capsaicin-induced pain than men [94]. The differential modulation of capsaicin responses by female and male hormones might provide a rationale to explain this observation. 

Fig. 5.9(b) Sex differences in responsiveness to female hamster vaginal fluid (FHVS) androgen (T) effects on central transmission pathways (from Swann and Fiber, 1997). 

The influence of gonadal hormones on prepubertal animals suggests some steroidal sensitivity in adults with regard to F. elicitation. Young male sheep are induced to perform F. in response to exogenous T and to 17-p-estradiol F. in female red deer is also sensitive to T injections (Parrott, 1978 Fletcher, 1978). Sex differences can interact with the hormonal state where social conditions vary. Female cats (intact) display F. to urine marks only in the absence of males testosterone propionate induced F. in spayed females towards estrous females (Verbeme, 1976 Hart and Leedy, 1987), whereas an ovarian hormone (estradiol) failed to elicit F. to males (intact, and sexually inactive), presumably indicative of social inhibition overriding steroid facilitation. 

Fig. 7.8 Sex differences in F. frequency (/hr) with age birth to one year, in captive Sable Antelope Hippotragus niger (from Thompson, 1995).

Collado P. and Segovia S. (1992). Female s DHT controls sex differences in the rat bed nucleus of the accessory olfactory tract. Neuroreport 3, 327-329. 

Del Cerro M., Chirino R Mayer A.D. and Rosenblatt J.S. (1995). Sex-differences in sensitisation latencies in maternal behavior induced in male and female rats after vomeronasal organ removal. Dev Psychobiol 28, 183 abs. 

Floody O. and Comerci J. (1987). Hormonal control of sex-differences in UHF production by hamsters. Horm Behav 2, 17-35. 

Goodrich B.S. and Myktowycz R. (1972). Individual and sex-differences in chemical composition of pheromone-like substances from skin giands of rabbit. J Mammal 53, 540-548. 

Guillamon A. and Segovia S. (1997). Sex differences in the vomeronasal system. Brain Res Bull 44, 377-382. 

Janus C. and Holman S. (1989). Development of sex differences in the response of Spiny Mouse pups to adult male odors. Physiol Behav 46, 895-900. 

Kelliher K Chang Y., Wersinger S. and Baum M. (1998). Sex difference and testosterone modulation of pheromone-induced neuronal fos in the Ferret s main olfactory bulb and hypothalamus. Biol Reprod 59, 1454-1463. 

Segovia S. and Guillamon A. (1993). Sex dimorphism in the vomeronasal pathway and sex differences in reproductive behaviours. Brain Res Rev 18, 51-74. 

A sex difference in the rate of conversion of DIMP to its primary metabolite was observed after intravenous administration of 14C-DIMP in rats (Bucci et al. 1992). The males appeared to convert DIMP to IMPA more actively than the females. The apparent plasma elimination half-life of DIMP was about 45 minutes in males and up to 250 minutes in females. Both the rate and total excretion of the administered dose in urine were also higher in male rats. However, this sex difference was not observed for orally-administered DIMP in minks (Bucci et al. 1992 Weiss et al. 1994). 

Roman, F., Garcia-Sanchez, F., Martinez-Selva, J., Gomez-Amor, J. and Carrillo, E., Sex differences and bilateral electrodermal activity. PavlJ Biol Science 24, ISO-155, 1989. 

Harrod, S.B., Mactutus, C.F., Bennett, K., Hasselrot, U., Wu, G., Welch, M., and Booze, R.M., Sex differences and repeated intravenous nicotine behavioral sensitization and dopamine receptors, Pharmacol. Biochem. Behav, 78, 581, 2004. 

Perkins, K.A., Gerlach, D., Vender, J., Grobe, J., Meeker, J., Hutchison, S. Sex differences in the subjective and reinforcing effects of visual and olfactory cigarette smoke stimuli. Nicotine Tob. Res. 3 141, 2001. 

Staley, J., Krishnan-Sarin, S., Zoghbi, S. et al. Sex differences in [123I]beta-CIT SPECT measures of dopamine and serotonin transporter availability in healthy smokers and nonsmokers. Synapse. 41 275, 2001. 

Gilbert AN, Knasko SC and Sabini J (1997). Sex differences in task performance associated with attention to ambient odour. Archives of Environmental Health, 52, 195-199. 

Zubieta, J. K., Huguelet, P., Ohl, L. E. etal. High vesicular monoamine transporter binding in asymptomatic bipolar I disorder sex differences and cognitive correlates. Am. J. Psychiatry 157 1619-1628, 2000. 

Fortoul, T.I. et al., Sex differences in bronchiolar epithelium response after the inhalation of lead acetate, Toxicology 207, 323, 2005. 

Montano, M.M. et al., Sex differences in plasma corticosterone in mouse fetuses are mediated by differential placental transport from the mother and eliminated by maternal adrenalectomy or stress, J. Reprod. Fertil., 99, 283, 1993. 

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