Factors influencing the fecal egg and oocyst counts of parasites of wild European rabbits Oryctolagus cuniculus (L.) in Southern Western Australia

Abundance of intestinal parasites was monitored by fecal egg and oocyst counts for samples of wild rabbits Oryctolagus cuniculus with different levels of imposed female sterility from 12 populations in southwestern Australia. Differences in egg counts of Trichostrongylus retortaeformis between seasons and age groups were dependent on the sex of the host. Pregnancy may have been responsible for these differences because egg counts were consistently higher in intact females than in females surgically sterilized by tubal ligation. Egg counts for Passalurus ambiguus were influenced by season and host age but there were no differences between sexes or between intact and sterilized female rabbits. No differences were detected in the oocyst counts of the 8 species of Eimeria between male and female rabbits or between intact and sterilized females. Seasonal differences were detected in oocyst counts of Eimeria flavescens and Eimeria stiedai. The overwhelming determinant of coccidian oocyst counts was host age, with 6 species being much more abundant in rabbits up to 4 mo of age. There was a suggestion that egg counts of T. retortaeformis and oocyst counts of several species of Eimeria were reduced in populations where rabbit numbers had been depressed for at least 2 yr, but there was no evidence that short-term variations in rabbit numbers had a measurable effect on parasite abundance.     

Territory fidelity, space use, and survival rates of wild coyotes following surgical sterilization

Sterilization of wild canids is being used experimentally in many management applications. Few studies have clearly demonstrated vasectomized and tubal-ligated canids will retain pair-bonding and territorial behaviors. We tested whether territory fidelity, space use, and survival rates of surgically sterilized coyote (Canis latrans) packs were different from sham-operated coyote packs. We captured and radio-collared 30 coyotes in December 2006. Sixteen of these animals were sterilized via vasectomy or tubal ligation, and 14 were given sham-surgeries (i.e., remained intact). We monitored these animals using telemetry and visual observations through 2 breeding seasons and 1 pup-rearing season from December 2006 to March 2008. Mean pack size was not significantly different between sterile and intact coyote packs. We found no difference in home range size between sterile and intact coyotes. We found differences in home range and core area overlap between sterile and intact coyote packs in some seasons; however, this difference may have existed prior to sterilization. Home range fidelity was not significantly different between sterile and intact coyotes. All coyotes had higher residency rates during the breeding season, with no differences between sterile and intact coyotes. Survival rates were correlated with biological season, but there were no differences in survival rates between sterile and intact coyotes. We concluded that surgical sterilization of coyotes did not affect territory fidelity, survival rates, or home range maintenance.     

Utilization of Matrix Population Models to Assess a 3-Year Single Treatment Nonsurgical Contraception Program Versus Surgical Sterilization in Feral Cat Populations

This study constructed matrix population models to explore feral cat population growth for a hypothetical population (a) in the absence of intervention; (b) with a traditional surgical sterilization-based trap, neuter, and return program; and (c) with a single treatment 3-year nonsurgical contraception program. Model outcomes indicated that cessation of population growth would require surgical sterilization for greater than 51% of adult and 51% of juvenile (<1 year) intact female cats annually, assuming an approximate 3-year mean life span. After the population stabilizes, this would equate to sterilizing approximately 14% of the total female population per year or having approximately 71% of the total female and 81% of the adult female population sterilized at all times. In the absence of juvenile sterilization, 91% of adult intact females would need to be sterilized annually to halt population growth. In comparison, with a 3-year nonsurgical contraception program, an annual contraception rate of 60% of female juvenile and adult intact cats would be required to halt population growth, assuming that treated cats were retrapped at the same rate after 3 years.     

Effects of adult chill treatments on mate attracting potential for irradiated Mexican fruit fly males

Mexican fruit flies, Anastrepha ludens (Loew), that are reared, sterilized and released for maintenance of a fly free zone in south Texas and for population eradication in California are routinely chilled for 1 to 2 h to facilitate handling and dispersal. While a number of behavioral, physical and physiological characteristics are routinely monitored as part of a quality control program, the effect of the chilling process on the ability of these males to attract wild females has not been evaluated. Tests were performed to compare the mate attracting effectiveness of mass reared, sterilized, chilled males with sterile males that had not been chilled and with recently colonized males. Tests were performed with two recently colonized strains of females in a large cage and males of the three types in plastic cups set on top of the cage. Controls consisted of empty cups. Results showed no significant differences among the three types of males. In tests with the most recently collected (least laboratory adapted) wild strain of females, the chilled males attracted the most females. Fly age and time of day were both significantly related to total attractiveness of males. Number of females responding to males per day increased over the five-day test period. The time period when female response was greatest was variable among the tests.     

Sex differences in adrenal function in the lizard Cnemidophorus sexlineatus: II. Responses to acute stress in the laboratory.

Circulating concentrations of plasma corticosterone and gonadal steroids were measured in intact and gonadectomized male and female lizards (Cnemidophorus sexlineatus) following acute stress (handling) in the laboratory. There was a significant increase in plasma corticosterone after stress. Whereas intact females exhibited greater concentrations of corticosterone relative to intact males, ovariectomized females exhibited lower concentrations of corticosterone relative to castrated males. In addition to sex differences in corticosterone responses to gonadectomy, progesterone was elevated by stress in both intact and ovariectomized females but not in males. Corticosterone adjusted for castration and handling in males was negatively correlated with the plasma androgen level. The adrenal responsiveness of males to acute stress may be attenuated by androgens presumably secreted by the testis. Not only does adrenal function influence reproduction, but adrenal responses differ between males and females, and appear to be influenced by the gonadal axis. The sex differences in adrenal responses to stress likely reflect different reproductive strategies and nutritional requirements of males and females during the breeding season.     

Sexually dimorphic effects of morphine and MK-801: sex steroid-dependent and -independent mechanisms.

Rats show gender differences in responses to morphine and the N-methyl-D-aspartate receptor antagonist dizocilpine (MK-801); the role of sex steroids in mediating these differences is unclear. We tested the overall hypothesis that circulating gonadal steroids determine the gender differences in morphine- and MK-801-induced behavior and c-Fos expression. Morphine caused a greater expression of c-Fos in the striatum of intact males than of that females, which was independent of sex steroids. MK-801 completely inhibited morphine-induced c-Fos in intact females but only caused partial inhibition in intact males; castrated males showed complete inhibition, which was reversed by testosterone, but gonadal steroids had no effect on this response in females. In thalamus, there was a large sex difference in the response to MK-801 that was independent of gonadal steroids. Behavioral responses to morphine were greater in males, but responses to MK-801 were greater in females; both were sex steroid independent. These findings show significant sex differences in response to morphine and MK-801 that are mediated by sex steroid-dependent and -independent mechanisms, which may be important in treatment outcomes of drug addiction.     

Hormonal and experiential control of female-male mounting in the female rat

Mounting behavior in the female rat has been studied extensively in same-sex interactions, but not in the heterosexual dyad. The present study examined the display of female mounting of castrated noncopulating male rats (FMM). Ovariectomized (OVX) sexually naive female rats (N = 80) were given either estrogen (E) + progesterone (P), E + oil (O), P + O, or O + O treatment for five tests with castrated male rats. FMMs were observed in both the E + P and E + O females. The influence of the ovarian cycle on FMM was also investigated. Vaginal smears from sexually naive females (N = 16) were taken daily for 12 days immediately after testing with castrated males. FMM frequency was greatest during Proestrus. Finally, OVX females (N = 30) treated with E + P were given either 0, 1, 10 multi-ejaculatory heterosexual experiences with intact, sexually experienced males, prior to tests with intact, copulating or castrated, noncopulating males for five tests. Sexually naive females displayed a greater number of mounts relative to the sexually experienced females when tested with castrated, noncopulating males. In contrast, very few FMMs were observed in females of any group tested with intact, copulating males. These data suggest that FMM occurs naturally in rats as a "super-solicitational" behavior that is modified by hormone treatment and prior heterosexual experience.     

Female-typical sexual behavior of rhesus and defeminization by androgens given prenatally

Adult rhesus monkeys were observed in standardized tests for female-typical sexual and related social responses. In the first experiment reported, 7 castrated males and 5 spayed females were paired with each of 4 intact males on two occasions following intramuscular injection with estradiol benzoate (EB) (6 micrograms/kg X 14 days) and on two other occasions without such treatment. In tests without EB, males and females did not behave differently toward the intact male partners, and all responses were displayed at low frequencies. In tests with EB, females showed reliably higher frequencies than males of approaching, sitting close to, grooming, and soliciting, and they presented to a higher proportion of the male partner's sexual contacts. EB reliably increased the frequency of display of all of these same five responses in females but not in castrated males. The intact male partners displayed reliably fewer approaches, sexual contacts, mounts, intromissions, and ejaculations to castrated males than to spayed females regardless of estrogenization. In a second experiment 10 intact adult pseudohermaphroditic females and 6 intact control females were tested following EB injections with each of the same 4 intact males. Pseudohermaphrodites were experimentally produced by injecting pregnant females with either testosterone propionate (TP) or dihydrotestosterone propionate (DHTP). Pseudohermaphrodites, regardless of type of androgen used in their production, showed reliably fewer solicits than controls to male partners. Moreover, they displayed most of the other responses at lower average frequencies than controls. Frequencies of intromission and ejaculation by intact male partners were reliably lower with pseudohermaphrodites than with control females, but frequencies of approach, sexual contact, and mount were not reliably different. We conclude that in this testing and measurement situation male and female rhesus monkeys differ markedly in the degree of expression of female-typical sexual behaviors, and genotypic males are behaviorally less responsive to estrogens than females. Exposing genotypic females to androgens during fetal life decreases the expression of female-typical, estrogen-influenced responses, and the effect is most pronounced on those soliciting responses that subserve proceptivity.     

Immunoreactive α melanocyte stimulating hormone,its distribution in the gastrointestinal tract of intact and hypophysectomized rats

The presence of immunoreactive α melanocyte stimulating hormone (IαMSH) was investigated in both mucosal and muscular layers of the various areas of the gastrointestinal tract. IαMSH was present in both layers in all areas of the gastrointestinal tract but the esophageal mucosa and muscularis in saline extracts. The highest concentrations were found in the duodenum. Hypophysectomized males tended to have higher content than intact males. There was no difference between intact estrogen-primed females and hypophysectomized females up to 1 month post hypophysectomy in any area. The tract of 3 month hypophysectomized females showed lower levels than the intact estrogen-primed females in 5 areas; however, in similar groups of 3 month hypophysectomized females which were estrogen primed, 8 of the 10 areas contained more IαMSH than the intact estrogen-primed females. Acid extracts from female rats during the estrous cycle showed no cycle-dependent differences. Comparison of acid and saline extracts showed an absence of IαMSH in gastric tissues and a decrease in the duodenal muscularis in acid extracts but no consistent differences were found in other areas. These results suggest that the IαMSH found in the gastrointestinal tract is not of pituitary origin but may be produced in the gastrointestinal tract. The induction of increased content by estrogen priming in hypophysectomized rats suggests that estrogen priming may induce production. The absence of IαMSH in acid extracts of the stomach suggests that a difference in distribution of pro-opio-cortin products may exist in the gastrointestinal tract.     

Productivity modifications to flour beetles (Coleoptera: Tenebrionidae) by gamma radiation (60Co) of one or both sexes and by the addition of radiated males or females to population

The effects on productivity by the addition of various numbers of radiated adult males or females to populations of two densities were determined for two species of flour beetles. Modifications in productivity after exposure to gamma radiation from⁶⁰Co included:

1. females of T. confusum were sterilized by an exposure between 2620 to 5230 R.
2. females of T. castaneum were not sterilized by 10, 200 R.
3. males were not sterilized by 10, 200 R.
4. sterile females may serve as depositories for normal sperm thereby reducing the productivity. Addition of such females to populations of flour beetles did not reduce the numbers of progeny.
5. since sterile females did not suppress population development, and since they destroy grain and cereal products, they should be eliminated from control programs featuring the sterile insect release technique.
6. population density decreased the numbers of progeny.

The use of the sterile insect release technique to control insects of stored grain products does not seem likely with present day sanitary standards since large numbers of insects need be added to effect control.     

Gender differences and time course of castration-induced changes in porphyrins, indoles, and proteins in the Harderian glands of the Syrian hamster.

Sexual differences and the effects of orchidectomy were determined for porphyrin and melatonin concentrations and for the activities of the enzymes N-acetyltransferase and hydroxyindole-O-methyltransferase, which synthesize melatonin from serotonin, in the Harderian glands of the Syrian hamster. Porphyrin concentrations in intact males were about 1/400th those of intact females. Castration for 1 week increased male Harderian porphyrin concentrations 10-fold; by 3 weeks, castrated male porphyrin levels were 140 times those of control values. N-Acetyltransferase activity in intact male Harderian glands was about 4 times that of females. Castration led to a drop in N-acetyltransferase activity to female levels within 2 weeks. Hydroxyindole-O-methyltransferase activity was 7 times higher in females than in males and castration had no effect on male Harderian hydroxyindole-O-methyltransferase activity. Neither gender nor castration influenced Harderian melatonin concentrations. Soluble proteins in Harderian glands from male and female hamsters and from male hamsters castrated for 1 and 4 weeks were examined by sodium dodecyl sulfate--polyacrylamide gel electrophoresis. The gel profiles revealed several differences among the protein distribution in male and female gland lysates. Orchidectomy led to a female protein pattern within 4 weeks.     

雄性不育对布氏田鼠交配行为和繁殖的影响

利用雄性结扎不育方法研究雄性结扎不育对布氏田鼠交配行为和繁殖的影响。结果表明：雄性结扎不育后不影响布氏田鼠雌雄两性的交配行为;不育雄性的存在对雌性的正常交配产生了干扰,降低了雌性的有效交配次数,并导致雌性怀孕率和产仔数的下降。结果一方面说明结扎不育雄性方法可用于布氏田鼠的不育控制研究,另一方面为不育后的竞争性繁殖干扰假设提供了实验证据。     

Gender-related distinctions in protein kinase C activity in rat vascular smooth muscle

Gender differences in vascular reactivity have been suggested; however, the cellular mechanisms involved are unclear. We tested the hypothesis that the gender differences in vascular reactivity reflect gender-related, possibly estrogen-mediated, distinctions in the expression and activity of specific protein kinase C (PKC) isoforms in vascular smooth muscle. Aortic strips were isolated from intact and gonadectomized male and female Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR). Isometric contraction was measured in endothelium-denuded aortic strips. PKC activity was measured in the cytosolic and particulate fractions, and the amount of PKC was measured using Western blots and isoform-specific anti-PKC antibodies. In intact male WKY rats, phenylephrine (Phe, 10(-5) M) and phorbol 12,13-dibutyrate (PDBu, 10(-6) M) stimulated contraction to 0.37 +/- 0.02 and 0.42 +/- 0.02 g/mg tissue wt, respectively. The basal particulate/cytosolic PKC activity ratio was 0.86 +/- 0.06, and Western blots revealed alpha-, delta-, and zeta-PKC isoforms. Phe and PDBu increased PKC activity and caused significant translocation of alpha- and delta-PKC from the cytosolic to particulate fraction. In intact female WKY rats, basal PKC activity, the amount of alpha-, delta-, and zeta-PKC, the Phe- and PDBu-induced contraction, and PKC activity and translocation of alpha- and delta-PKC were significantly reduced compared with intact male WKY rats. The basal PKC activity, the amount of alpha-, delta-, and zeta-PKC, the Phe and PDBu contraction, and PKC activity and alpha- and delta-PKC translocation were greater in SHR than WKY rats. The reduction in Phe and PDBu contraction and PKC activity in intact females compared with intact males was greater in SHR ( approximately 30%) than WKY rats ( approximately 20%). Phe and PDBu contraction and PKC activity were not significantly different between castrated males and intact males but were greater in ovariectomized (OVX) females than intact females. Treatment of OVX females or castrated males with 17 beta-estradiol, but not 17 alpha-estradiol, subcutaneous implants caused significant reduction in Phe and PDBu contraction and PKC activity that was greater in SHR than WKY rats. Phe and PDBu contraction and PKC activity in OVX females or castrated males treated with 17 beta-estradiol plus the estrogen receptor antagonist ICI-182,780 were not significantly different from untreated OVX females or castrated males. Thus a gender-related reduction in vascular smooth muscle contraction in female WKY rats with intact gonads compared with males is associated with reduction in the expression and activity of vascular alpha-, delta-, and zeta-PKC. The gender differences in vascular smooth muscle contraction and PKC activity are augmented in the SHR and are possibly mediated by estrogen.     

The effects of gonadal hormones on scent marking and related behavior and morphology in female gray short-tailed opossums (Monodelphis domestica)

The hormonal control of scent marking and related behavior and morphology was examined in female gray short-tailed opossums. Females rarely scent marked when intact or following ovariectomy. Testosterone (T) but not estradiol (E) treatment stimulated chest marking while either hormone stimulated head marking in ovariectomized females tested alone. When the same females were tested with males, T-treated females showed little scent marking of any type; E-treated females showed hip marking in significantly more tests than females in the other treatment groups. Suprasternal scent glands (absent in intact females) and phalluses of females that received T were significantly larger than those of animals that received E or control animals. These findings are discussed with respect to similarities and differences between marsupial and eutherian females and between male and female gray opossums in the hormonal control of sexually dimorphic behavior and morphology.     

Evidence for Sexual Differentiation of Glia in Rat Brain

It is well established that gonadal steroids mediate sexual differentiation of the brain via direct effects on neurons during a restricted critical period. In addition, estrogen can influence glial morphology in the adult brain, andin vitrostudies suggest estrogen induces glial differentiation. However, there is a lack ofin vivoevidence for steroid effects on glia during the critical period. We report here a hormone-mediated sexual differentiation of arcuate glia as early as Postnatal Day 1. Using glial fibrillary acidic protein immunoreactivity (GFAP-ir), we compared the responsiveness of astroglia in the rat arcuate nucleus among five hormonally different groups. The results indicate increased GFAP-ir cell surface area 24 hr after hormonal manipulation in castrate males compared to intact males, intact females (ANOVA;P< 0.01), and females injected with testosterone propionate (50 μg; ANOVA;P< 0.05). However, astroglia in intact males extended their processes significantly greater distances from the cell body compared to all other treatment groups (ANOVA;P< 0.01). The GFAP-ir cells were categorized into four distinct classes ranging from a simple bipolar to a fully stellate morphology. The frequency distribution of classes varied between groups with more stellate cells found in intact males. Finally, these sex differences in arcuate glia persisted into adulthood. We hypothesize that during the critical period, testosterone, or its metabolite estrogen, induce sexual differentiation of glia. We further hypothesize that in females glial cells remain partially undifferentiated and this may be important to glial plasticity seen in adult female arcuate.     

Gender Differences in Histamine-Induced Depolarization and Inward Currents in Vagal Ganglion Neurons in Rats

Evidence has shown gender differences regarding the critical roles of histamine in the prevalence of asthma, anaphylaxis, and angina pectoris. Histamine depolarizes unmyelinated C-type neurons without any effects on myelinated A-type vagal ganglion neurons (VGNs) in male rats. However, little is known if VGNs from females react to histamine in a similar manner. Membrane depolarization and inward currents were tested in VGNs isolated from adult rats using a whole-cell patch technique. Results from males were consistent with the literature. Surprisingly, histamine-induced depolarization and inward currents were observed in both unmyelinated C-type and myelinated A- and Ah-type VGNs from female rats. In Ah-type neurons, responses to 1.0 μM histamine were stronger in intact females than in males and significantly reduced in ovariectomized (OVX) females. In C-type neurons, histamine-induced events were significantly smaller (pA/pF) in intact females compared with males and this histamine-induced activity was dramatically increased by OVX. Female A-types responded to histamine, which was further increased following ovariectomy. Histamine at 300 nM depolarized Ah-types in females, but not Ah-types in OVX females. In contrast, the sensitivity of A- and C-types to histamine was upregulated by OVX. These data demonstrate gender differences in VGN chemosensitivity to histamine for the first time. Myelinated Ah-types showed the highest sensitivity to histamine across female populations, which was changed by OVX. These novel findings improve the understanding of gender differences in the prevalence of asthma, anaphylaxis, and pain. Changes in sensitivity to histamine by OVX may explain alterations in the prevalence of certain pathophysiological conditions when women reach a postmenopausal age.     

Sex differences,laterality, and hormonal regulation of androgen receptor immunoreactivity in rat hippocampus

Sex differences, laterality, and hormonal regulation of androgen receptor (AR) immunoreactivity in rat hippocampal CA1 pyramidal cells were examined using the PG21 antibody. Adult male rats were either castrated or sham-operated at least 2 weeks prior to sacrifice. Gonadally intact females were sacrificed on the day of proestrus. Animals received an injection of either testosterone propionate (TP) or vehicle 2 h prior to sacrifice. Within CA1, both the intensity of staining and the number of AR+ cells were assessed. AR immunostaining was detected in all the groups with marked variation among them. The overall ranking of staining intensity was: gonadally intact males > females given TP > castrated males given TP > females > castrated males given vehicle. The number of AR+cells within subregions of CA1 showed the same basic pattern: among control-treated animals, gonadally intact males have more than females, but castrated males have the least, and acute TP treatment increases the number in both sexes. The increased level of AR immunoreactivity in CA1 of castrated males following acute TP treatment suggests that testicular androgens in adulthood normally increase AR immunoreactivity there, producing a sex difference favoring males in gonadally intact animals. We also found a higher number of AR+ CA1 cells on the left than on the right, but only in gonadally intact males and in females given TP. These results suggest that a laterality of AR distribution in the rat hippocampus may lead to lateralities in hippocampal structure and function.     

Infant-directed behavior in young rhesus monkeys: Sex differences and effects of prenatal androgens

Young (3–4 years old) laboratory-reared rhesus monkeys were observed in five 15-minute tests with 1–15-day-old infants. Males and females were equally likely to investigate infants. Females communicated more with infants by grin-lipsmacking and gurgling–-gestures that were not shown by any males. More females presented the ventrum to infants than did males. Females contacted infants more than did males by grooming, crouching over, and having full body contact with them. To see whether prenatal androgens produced the male pattern of response, we conducted similar tests with pseudohermaphrodites (prenatally androgenized genetic females) and neonatally castrated males. On most sexually dimorphic behaviors, pseudohermaphrodites behaved more like females than like males. Castrated males, like females and pseudohermaphrodites, crouched over infants more than did intact males. Castrated males differed from females only on one infant-directed response, the grin-lipsmack. These comparisons showed that defeminization of the repertoire of infant-directed responses was measurable only in intact males. We conclude accordingly that prenatal androgens alone are not responsible for defeminization of this repertoire and that a contribution from postnatal androgens is likely to be necessary.     

Gender differences in steroid modulation of angiotensin II-induced protein kinase C activity in anterior pituitary of the rat

To investigate whether the various steroid hormones can modulate the basal and angiotensin II-induced protein kinase C (PKC) activity in the anterior pituitary of the rat, female and male intact and ovariectomized female Wistar rats were treated in vivo with estradiol (E2), progesterone (P), dehydroepiandrostendione sulfate (DHEA-S), and pregnenolone sulfate (PREG-S). Estradiol caused the increase of basal PKC activity in intact and ovariectomized females, but did not change the enzyme activity in males. In ovariectomized animals the increase of PKC activity was lower than in intact females. Progesterone decreased PKC activity only in intact animals. DHEA-S strongly enhanced activity of PKC in ovariectomized females. Pregnenolone sulfate did not significantly change PKC function of all studied groups. Incubation with AngII enhanced the PKC activity in intact (without steroid treatment) animals of both genders. In females, AngII and estradiol together rise the PKC-stimulated phosphorylation in greater degree than used separately. Treatment with other investigated steroids reduced the effect of AngII. In intact males every examined hormone turned back the stimulatory effect of AngII on PKC activity. These data suggest that gender differences in PKC activity are likely related to hormonal milieu of experimental animals and may depend in part on the basic plasma level of estrogens.     

Social influences on plasma testosterone levels in male talapoin monkeys

Three social groups of laboratory-housed talapoin monkeys (Miopithecus talapoin) consisting of four adult males and four or five adult females, were observed over a 4-year period. All females were ovariectomized and given estradiol implants at intervals to render them sexually attractive; except for two castrated males with testosterone implants, all males were intact. Sexual and aggressive interactions were recorded, and testosterone levels were measured in plasma taken from males twice weekly. In each group males formed a linear dominance order, defined in terms of the direction of aggression between animals. The hormonal responses of intact males were monitored with respect to the presence of attractive females, access to these females, and transfer from the social group to isolation. In all groups the behavioral and endocrine responses of males to these treatments were rank related. In some instances, rising in rank was associated with elevated testosterone and falling in rank with decreased testosterone; these hormonal changes were associated with changes in sexual and aggressive interactions. The effects of sexual and aggressive behavior on plasma testosterone titers are discussed.