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Predictors of adolescent sexual behavior and intention: a theory-guided systematic review.

PURPOSE: To better understand why adolescents initiate sexual activity at early ages, we conducted a systematic literature review guided by eight key elements outlined in an integrative theoretical framework. METHODS: Using the matrix method for literature reviews, we extracted-from 69 published studies-statistically significant and nonsignificant findings (related to the attempted prediction/explanation of adolescents' sexual behavior and intention) and organized them using the various integrative model elements. We also assessed these publications' methodological quality including each study's deployment of theory, appropriate design, and data analytic/reporting techniques. RESULTS: Three integrative theoretical framework elements-intention, perceived norms, and an environmental constraint variable, time home alone-emerged as stable predictors of sexual behavior outcomes in this body of literature. This analysis revealed, however, a literature that has remained rather stagnant regarding its methodological quality, over time. CONCLUSIONS: Implications for adolescent sexual health promotion practice and research are discussed.

Adolescent↗

Appetitive as well as consummatory aspects of male sexual behavior in quail are activated by androgens and estrogens.

Appetitive male sexual behavior was measured in male quail with the use of a learned social proximity procedure that quantified the time spent by a male in front of a window providing a view of a female that was subsequently released into the cage, providing an opportunity for copulation. The learned response is not acquired by castrated males but can be acquired when castrates are treated with testosterone (T) or with the synthetic estrogen diethylstilbestrol or with the endogenous estrogen 17 beta-estradiol. Only birds that become sexually active acquire the response. Conversely, birds in which the consummatory copulatory behavior is disrupted by treatment with the antiestrogen tamoxifen lose the anticipatory response. These results demonstrate that appetitive sexual behavior is, like copulation, activated by T and by estrogens. This suggests that intracerebral aromatization of T also plays a critical role in the activation of this behavior.

Androgens↗

[Human papillomavirus infection, a possible biological marker of sexual behavior among university students].

OBJECTIVE: To estimate the prevalence of Human papillomavirus (HPV) among university students and to use it as a biological marker to assess sexual behavior. MATERIAL AND METHODS: A cross-sectional study was carried out between 2000 and 2001 among 194 students at Universidad Autónoma del Estado de Morelos, Mexico. A data collection instrument was applied and genital samples were taken to detect oncogenic HPV DNA. Data were analyzed using the chi-squared test and odds ratios. RESULTS: Overall HPV prevalence was 14.4%. Women who had had two or more sexual partners during the previous year showed a greater risk of HPV infection (OR 6.0, 95% CI 1.7-21.1), as did women who had used oral contraceptives and spermicides at their latest intercourse (OR 3.0, 95% CI 1.0-8.7). Males who consumed cocaine were at a greater risk of HPV infection (OR 7.6, 95% CI 1.3-45.1). CONCLUSIONS: HPV prevalence is relatively high. HPV is a reliable biological marker of sexual behavior among females. A greater sample size may be needed to assess its reliability among men.

Adolescent↗

Acculturation-related variables, sexual initiation, and subsequent sexual behavior among Puerto Rican, Mexican, and Cuban youth.

The relationship among acculturation-related variables, past sexual activity, and subsequent sexual behavior was examined for a sample of Latino youth in the United States over a 12-month period. A subsample from the National Longitudinal Study of Adolescent Health database was analyzed by means of a prospective design. History of sexual intercourse predicted subsequent sexual behavior over the ensuing 12 months. The acculturation-related variables were related to whether an adolescent reported being sexually active at Wave 1 but in a complex fashion. Among recent immigrants, youth from English-speaking homes were less likely to be sexually active than those from Spanish-speaking homes. The opposite was observed for youth who were born in the United States or who had resided in the United States most of their lives.

Acculturation↗

Inhibition of sexual behavior in female rats by intracerebral injections of Met-enkephalin in combination with an inhibitor of enkephalin degrading enzymes.

Injection of Met-enkephalin, either subcutaneously (10 or 100 microgram, s.c.), intracerebroventricularly (100 ng or 1 microgram, i.c.v.) or into the mesencephalic central gray (100 ng), had no inhibitory effect on sexual behavior in female rats. If combined with [(R)-3-(N-hydroxy)-carboxamido-2-benzylpropanoyl]-L-alanine (kelatorphan, 5 micrograms i.c.v.; 1.5 micrograms in the central gray; 200 micrograms s.c.), an inhibitor of enkephalin degrading enzymes, however, i.c.v. or central gray (100 ng), but not s.c. (100 micrograms), injection of Met-enkephalin suppressed the behavior. Injection of Leu-enkephalin, s.c. or i.c.v. alone or in combination with kelatorphan, had no inhibitory effect. Peptidases may rapidly inactivate Met-enkephalin after intracerebral injection and prevent the behavioral effect. Inhibition of sexual behavior by Met-enkephalin may occur during lactation, a physiological state when the behavior is suppressed by an opioid peptide.

Animals↗

Cervical dysplasia: association with sexual behavior, smoking, and oral contraceptive use?

Information on possible risk factors of cervical dysplasia, including indices of sexual behavior, smoking habits, and the use of oral contraceptives was obtained from a case-control study in Ontario in which 250 cases of histologically proved cervical dysplasia and 500 age-matched neighborhood controls were interviewed. Initial analysis showed an increased risk associated with more than one sexual partner, an early age at first intercourse, current smoking, the use and duration of use of oral contraceptives, and education. However, the increased risk of use and duration of use of oral contraceptives and education was reduced after adjustment for indices of sexual behavior and smoking. This finding does not confirm previously reported large adverse effects of pill use. The relationship between smoking and cervical dysplasia might be explained by some agent in cigarette smoke which depresses the immune mechanism, thus permitting a sexually transmitted agent to result in abnormal cellular development that leads to the onset of cervical dysplasia.

Adolescent↗

A critical role for the evolutionarily conserved gonadotropin-releasing hormone II: mediation of energy status and female sexual behavior.

GnRH is an evolutionarily conserved neuropeptide, of which there are multiple structural variants; the function of the most widespread variant, GnRH-II, remains undefined. GnRH-II may affect reproductive behavior; GnRH-II administration to female musk shrews reinstates mating behavior previously inhibited by food restriction. To determine whether this action of GnRH-II is universal, we conducted the following studies in mice. Ovariectomized mice were primed with estradiol benzoate and progesterone once a week and tested for sexual behavior. Females showing a lordosis quotient (LQ) of 50 or higher on the fourth trial underwent food deprivation (FD) for either 24 or 48 h before an additional behavior test. FD for 48 h significantly reduced LQ compared with ad libitum-fed females. Next, females were FD for 48 h or maintained on ad libitum feeding and retested for sexual behavior after an intracerebroventricular infusion of either GnRH-I, GnRH-II, or saline. GnRH-II, but not GnRH-I, significantly increased LQ in FD females compared with FD females treated with saline. Lordosis was unaffected by GnRH-II in females maintained on ad libitum feeding. To assess whether the GnRH-I receptor mediates GnRH-II's behavioral effects, underfed females were pretreated with the type 1 GnRH receptor antagonist Antide and retested for sexual behavior. Antide pretreatment did not prevent GnRH-II from promoting mating behavior, suggesting that GnRH-II's behavioral actions are mediated through the type 2 GnRH receptor. We speculate that GnRH-II acts via its own receptor as a regulatory signal in mammals to ensure that reproduction is synchronized with energetically favorable conditions.

Animals↗

Sexual behavior and injection drug use during pregnancy and vertical transmission of HIV-1.

We evaluated maternal sexual behavior and injection drug use practices as possible risk factors for vertical transmission of human immunodeficiency virus type 1 (HIV-1). Data were analyzed from the Mothers and Infants Cohort Study, a prospective study in Brooklyn and the Bronx, New York. A total of 207 mother-infant sets were enrolled between 1986 and 1991 and followed for up to 4 years after the enrollment visit during pregnancy. HIV-1 transmission occurred in 49 of 201 mother-infant sets, yielding an overall transmission rate of 24.4% (95% confidence interval (CI) = 18.7% to 31.0%). Increased frequency of vaginal intercourse after the first trimester of pregnancy was positively associated with vertical transmission of HIV-1 (trend p = 0.03). A lifetime history of injection drug use was not associated with vertical transmission. However, a history of combined cocaine and heroin injection after the first trimester of pregnancy was associated with vertical HIV-1 transmission, particularly among women with CD4+ lymphocyte levels of 20% or higher (risk ratio = 4.0; 95% CI = 2.0 to 8.1). Cocaine and heroin injection drug use after the first trimester accounted for most of the relation between preterm birth and vertical HIV-1 transmission in this cohort. Maternal coinfection with hepatitis C virus or human T-cell lymphotropic virus types I and II could not explain these observations, because coinfection with these viruses had no detectable effect on HIV-1 transmission. These results suggest that maternal sexual behavior and injection drug use practices during the second and third trimester of pregnancy may modify the risk of vertical HIV-1 transmission.

Acquired Immunodeficiency Syndrome↗

Cytokines inhibit sexual behavior in female rats: I. Synergistic effects of tumor necrosis factor alpha and interleukin-1.

The secretion of cytokines such as tumor necrosis factor alpha (TNFalpha) and interleukin-1 (IL-1) during immune activation induces sickness behavior. We have previously demonstrated that administration of either lipopolysaccharide (LPS) or IL-1 suppresses sexual behavior in female, but not in male rats. In the present study we sought to determine some of the mechanisms that are involved in mediating the alterations of female sexual behavior during immune activation. We report that sexual motivation of estrous females was reduced by intracerebroventricular administration of either recombinant rat (rr)TNFalpha (7.5 microg/rat) or rrIL-1beta (100 ng/rat), whereas sexual receptivity was altered only by IL-1beta. A significant reduction of both sexual motivation and receptivity was also induced by the combined administration of subthreshold doses of TNFalpha (3 microg/rat) and IL-1beta (20 ng/rat). These findings indicate that TNFalpha and IL-1beta act synergistically to suppress sexual motivation and receptivity. Moreover, LPS (100 microg/kg, ip)-induced reduction of sexual motivation was antagonized by the combined administration of the TNFalpha synthesis blocker pentoxifylline (50 mg/kg, ip) and IL-1 receptor antagonist (10 mg/kg, ip), but not by the administration of each of these substances by itself. In contrast, LPS-induced reduction of sexual receptivity was completely prevented by pentoxifylline. These findings indicate that the effects of LPS on sexual motivation are mediated by the synergistic effects of TNFalpha and IL-1, but only TNFalpha is required for the effect of LPS on receptivity.

Animals↗

Staff members' attitudes toward the sexual behavior of mentally retarded residents.

Seventy-five staff members from four private residential facilities for mentally retarded adults were surveyed to elicit their attitudes toward the sexual behavior and sexual knowledge of residents in their care. Facility policies and programs applicable to residents' sexuality were also the subject of inquiry. Comparable attitudinal surveys and studies dealing with the sexuality of mentally retarded persons were reviewed in the context of the present findings.

Adolescent↗

Effect of Catha edulis foresk (khat) extracts on male rat sexual behavior.

Khat chewing is a widespread habit that has a deep-rooted socio-cultural tradition in East Africa and in the Middle East. Although a number of investigations have been carried out using cathinone, the psychoactive component of khat, these may not wholly reflect the behavioral effects observed after administering khat in a dosage similar to those used traditionally. The aim of the present study was to evaluate the effect of sub-chronically administered khat extract with or without alcohol on sexual behavior in male rats. Adult albino wistar male rats were administered either with khat extracts (100, 200, 400mg/kg), amphetamine (1mg/kg), sildenafil (1mg/kg), ethanol (2ml/kg of 2% and 10%), or a combination of khat and ethanol (2%+10%) by intragastric gavage orally for 15 days. Khat (400mg/kg) treated rats demonstrated a statistically significant increase in all sexual parameters except in mounting frequency, intercopulatory interval and copulatory efficiency. Whereas, khat (200mg/kg) treated rats showed a statistically significant increase only in ejaculation latency (P<0.01). In marked contrast, low dose (100mg/kg) of khat extract was found to significantly reduce both mount latency (P<0.05) and intromission latency P<0.01) thereby enhancing sexual motivation/arousal in male rats. Similar results were obtained when khat extract (200mg/kg) and ethanol (10%) were administered concomitantly despite the inhibitory effect observed in male sexual behavior when administered alone. From the present study it can be concluded that higher doses of the extract inhibit sexual behavior in male rats. In contrast, low dose of the extract as well as the concurrent administration of the extract followed by ethanol was found to enhance male rat sexual motivation/arousal.

Amphetamine↗

Social influences on the sexual behaviors of adolescent girls in at-risk circumstances.

OBJECTIVE: To describe social influences on girls' sexual behaviors. DESIGN: Descriptive, exploratory study using interviews with five focus groups. SETTING/PARTICIPANTS: 48 adolescent girls, ages 12 to 16 years, who were confined in a juvenile detention center for a variety of charges. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Girls' perceptions of influences on their sexual behaviors. RESULTS: The analysis revealed three themes: the influence of traditional gender roles, a lack of power in heterosexual relationships, and an ongoing search for romance. CONCLUSIONS: The social context of adolescent girls' lives can promote sexual activity and unprotected sex. Effective prevention efforts must acknowledge the context within which sexual risk occurs and address motivations and barriers in the target population.

Adolescent↗

Sexual behavior increases c-fos expression in the forebrain of the male rat.

The ability of a wide variety of pharmacological and physiological stimuli to increase neuronal expression of Fos has led to the suggestion that it might serve as a marker of neuronal activation. Psychomotor stimulants increase the release of dopamine from the terminals of nigrostriatal and mesolimbic neurons and enhance Fos immunoreactivity in the striatum and nucleus accumbens (NAc). Because sexual behavior also increases dopamine release in these and other forebrain regions, the present study examined the effect of copulation on Fos immunoreactivity in the forebrain of intact, sexually active male rats. Sexual behavior produced a striking increase in Fos immunoreactivity in the medial preoptic area (MPOA), NAc, bed nucleus of the stria terminalis and piriform cortex. However, no increase in Fos immunoreactivity was observed in the striatum. These results are consistent with neurochemical, physiological, and behavioral data suggesting that the MPOA and NAc are important substrates of sexual behavior.

Animals↗

The role of 5alpha-reductase activity in sexual behaviors of the green anole lizard.

Both testosterone (T) and its metabolite, 5alpha-dihydrotestosterone (DHT), can facilitate male sexual behavior in the lizard Anolis carolinensis. The present study addresses the role of DHT synthesis in regulating male sexual behavior by inhibiting 5alpha-reductase, the enzyme that converts T into DHT. In two separate experiments (one replacement and one maintenance paradigm), breeding adult males were castrated and implanted with capsules of T, DHT, or a control capsule (blank, BL). The animals were then injected with the 5alpha-reductase inhibitor, FCE, or with steroid suspending vehicle (SSV) as a control. Both experiments produced similar results. Overall, T was most effective in eliciting courtship and copulatory behaviors above control levels. In both experiments, treatment with FCE attenuated the T-induced effects on courtship behavior, whereas the inhibition of 5alpha-reductase activity resulted in modest and inconsistent effects on the latency to intromission and the proportion of copulating males. DHT treatment did not significantly increase courtship or copulatory behaviors above control levels. These results suggest that (a) 5alpha-reductase activity is necessary but that DHT alone is not sufficient for stimulating courtship in male A. carolinensis; and (b) courtship behavior is more sensitive than copulatory behavior to the activity of the androgen metabolizing enzyme.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗

Junior high school students' perceptions regarding nonconsensual sexual behavior.

This study assessed early adolescents' attitudes and perceptions regarding nonconsensual sexual activity. A total of 371 surveys (94% return rate) was completed. More than one-third of respondents (35%) reported they had engaged in sexual intercourse; 17% reported having been sexually coerced by a teen-ager; 19% reported feeling pressure from their friends to have intercourse; 7% reported having been sexually coerced by an adult; and 6% reported having sexually coerced someone else. Students also demonstrated lack of knowledge regarding nonconsensual sexual behaviors. Analysis of variance tests determined if knowledge (KN), attitudes (AT), behavioral intentions (BI), and locus of control (LC) changed across specific background and demographic variables. One background variable (having been sexually coerced by a teen-ager) was associated with high risk orientation (lower scores) on all four subscales. Lower scores also were associated with being male (KN, AT, BI), having sexually coerced someone else (KN, AT, BI), having been sexually coerced by an adult (AT, BI), and having engaged in sexual intercourse (AT, BI).

Adolescent↗

Sexual behavior and attitudes of university students in Northern Ireland.

Two surveys of a Northern Ireland student sample were conducted in 1987 and 1988. A total of 419 female and 201 male subjects completed self-administered anonymous questionnaires concerning their behavior, knowledge, and attitudes towards sex, AIDS, homosexuality, contraception, and relationships. Results indicated a relatively low level of sexual experience, and for those with experience, relatively few partners. The possible influences of gender and religiosity on sexual behavior and attitudes, in the context of Northern Ireland, are discussed. Subjects reported considerable variation in the amount of sex education, but the majority received little or none. This student sample held relatively conservative attitudes towards love, sex, and marriage and this was particularly true for females and for regular churchgoers. In addition, attitudes towards homosexuality were negative (particularly among regular churchgoers). Attitudes towards contraception were more positive than expected among Catholic subjects, and few indicated that they would refuse to use contraceptives on principle. Responses to items about AIDS were highly uniform, suggesting that much of the information made available to the public has been absorbed. However, the lack of uniformity of response to more general items about sex, relationships, and contraception may indicate that fundamental changes in sexual behavior are unlikely to be brought about by influencing a rather narrowly defined set of attitudes about AIDS.

Acquired Immunodeficiency Syndrome↗

Differential effects of D1 and D2 dopamine-receptor agonists and antagonists on appetitive and consummatory aspects of male sexual behavior in Japanese quail.

Pharmacological studies in Japanese quail based on behavioral tests with a variety of dopaminergic compounds suggest that the activation of D2 dopamine receptors inhibits, and the activation of D1 dopamine receptors enhances, appetitive and consummatory components of male sexual behavior. This hypothesis was tested by studying the behavioral effects of specific D1 and D2 dopaminergic-receptor agonists and antagonists in castrated male Japanese quail chronically treated with exogenous testosterone (subcutaneous Silastic implants). The effects of 5 compounds were tested: 1 D1 (SKF38393) and 2 D2 (PPHT and quinpirole) agonists, and 1 D1 (SCH23390) and 1 D2 (Spiperone) antagonist. All compounds were tested at a low and a high dose (0.1 and 1 mg/kg, respectively, for all drugs, except spiperone where the doses were 2 and 10 mg/kg). A consistent effect of all drugs on consummatory sexual behavior was observed: it was stimulated by the D1 agonist and the D2 antagonist, but inhibited by the D1 antagonist and the D2 agonists. Far fewer effects of the treatments were detected on the measures of appetitive behavior. Measures of appetitive behavior were decreased by the 2 D2 agonists, but not affected by the other treatments. These data suggest that male copulatory behavior in quail is stimulated by dopamine acting on D1 receptors, but inhibited by activation of the D2 receptor subtype. The partial dissociation observed between the effects of the same treatments on appetitive and consummatory aspects of sexual behavior also suggests that these 2 behavioral systems may be controlled by the action of dopamine on different neuronal systems.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

Electrical stimulation of male monkey's midbrain elicits components of sexual behavior.

We electrically stimulated the midbrain of male rhesus monkeys seated in a restraint chair facing the female partners and examined whether sexual behavior could be induced. When the midbrain was stimulated (0.2 ms, 50-500 microA and 50 Hz for 2.5 s), the male monkey touched and held the waist of his partner (latency; 0.9 +/- 0.4 s, mean +/- SD, n = 225), and then mounted her when she responded with presenting her hip toward him. However, this mounting, unlike when the hypothalamus was stimulated, did not lead to thrusting or ejaculation even if the stimulation continued. The sites in the midbrain where the stimulation elicited touching and mounting were the ventral tegmental area, the substantia nigra, the nucleus reticularis mesencephali and the nucleus reticularis pontis oralis et caudalis. Touching and mounting were not elicited when the partner was put away from the male or replaced by submissive male monkeys or humans. The findings suggest that the stimulation-evoked touching and mounting are components of copulatory behavior and that the midbrain structures may be involved in the sexual behavior of male monkeys.

Animals↗