Influencing antecedents of adolescent risk-taking behaviour in elementary school: results of a 4-year quasi-experimental controlled trial.

Effects of the life skills programme 'Eigenständig werden' (Becoming independent) on life skills and on identified antecedents of adolescent health risk behaviour, childhood internalizing and externalizing behaviour were tested in an elementary school setting. A quasi-experimental controlled trial with five repeated measures was conducted. Participants were 919 students from 50 elementary schools in Saxony, Germany. Outcomes were assessed by teachers' ratings. Growth-curve models revealed that the rate of decline in internalizing and externalizing behaviour was significantly higher in the intervention group-especially for students with high baseline levels of externalizing behaviour (P < 0.01). No general programme effects on the development of skills could be found (P = 0.22). The current study provides evidence that life skills programmes in elementary school may be an effective strategy in reducing antecedents of adolescent risk-taking behaviour.

[The impact of smoking in movies on children and adolescents. A systematic review]. / Der Einfluss des Rauchens in Filmen auf Kinder und Jugendliche. Eine systematische Ubersichtsarbeit.

In accordance with the conclusion of the US National Cancer Institute to consider smoking in films, in addition to other factors, as one risk factor for the initiation of smoking among children and adolescents, the World Health Organization has invited its member states to implement rules for limiting smoking depictions in films. Results of methodically high-value longitudinal and experimental studies which provide empirical evidence for the association between smoking depictions in films and smoking among children and adolescents are presented. Interpretation of this association as causal according to Hill criteria is discussed. In this systematic review, future personal and structural preventive interventions to address this problem in Germany are presented and discussed. Of special importance is the enhancement of both parental competence in media education as well as media literacy in children and adolescents. Rating films depicting smoking as approved for adults only could yield the largest effect, since it leads to an enduring reduction of exposure.

Social opportunity causes rapid transcriptional changes in the social behaviour network of the brain in an African cichlid fish.

Animals constantly integrate external stimuli with their own internal physiological state to make appropriate behavioural decisions. Little is known, however, about where in the brain the salience of these signals is evaluated, or which neural and transcriptional mechanisms link this integration to adaptive behaviours. We used an African cichlid fish Astatotilapia burtoni to test the hypothesis that a new social opportunity activates the conserved 'social behaviour network' (SBN), a collection of brain nuclei known to regulate social behaviours across vertebrates. We measured mRNA levels of immediate early genes (IEGs) in microdissected brain regions as a proxy for neuronal activation, and discovered that IEGs were higher in all SBN nuclei in males that were given an opportunity to rise in social rank compared to control stable subordinate and dominant individuals. Furthermore, because the presence of sex-steroid receptors is one defining criteria of SBN nuclei, we also tested whether social opportunity or status influenced androgen and oestrogen receptor mRNA levels within these same regions. There were several rapid region-specific changes in receptor mRNA levels induced by social opportunity, most notably in oestrogen receptor subtypes in areas that regulate social aggression and reproduction, suggesting that oestrogenic signalling pathways play an important role in regulating male status. Several receptor mRNA changes occurred in regions with putative homologies to the mammalian septum and extended amygdala, two regions shared by SBN and reward circuits, suggesting an important role in the integration of social salience, stressors, hormonal state and adaptive behaviours. We also demonstrated increases in plasma sex- and stress-steroids at 30 min after a rise in social rank. This rapid endocrine and transcriptional response suggests that the SBN is involved in the integration of social inputs with internal hormonal state to facilitate the transition to dominant status, which ultimately leads to improved fitness for the previously reproductively-suppressed individual.

Arginine vasotocin neuronal phenotypes among congeneric territorial and shoaling reef butterflyfishes: species, sex and reproductive season comparisons.

Arginine vasotocin (AVT) and the homologous arginine vasopressin (AVP) neuropeptides are involved in the control of aggression, spacing behaviour and mating systems in vertebrates, but the function of AVT in the regulation of social behaviour among closely-related fish species needs further clarification. We used immunocytochemical techniques to test whether AVT neurones show species, sex or seasonal differences in two sympatric butterflyfish sister species: the territorial monogamous multiband butterflyfish, Chaetodon multicinctus, and the shoaling polygamous milletseed butterflyfish, Chaetodon miliaris. The territorial species had larger AVT-immunoreactive (-ir) somata within the preoptic area, and higher AVT fibre densities within but not limited to the ventral telencephalon, medial and dorsal nucleus of the dorsal telencephalon, torus semicircularis, and tectum compared to the shoaling nonterritorial species. Furthermore, AVT-ir somata size and number did not differ among sexes or spawning periods in the territorial species, and showed only limited variation within the shoaling species. The distinct difference in AVT neuronal characteristics among species is likely to be independent of body size differences, and the lack of sex and seasonal variability is consistent with their divergent but stable social and mating systems. These phenotypic differences among species may be related to the influence of AVT on social spacing, aggression or monogamy, as reported for other fish, avian and mammalian models. The present study provides the first evidence for variation in vasotocin neural organisation in two congeneric and sympatric fish species with different social systems.

Annual cycles of steroid hormone production, gonad development, and reproductive behavior in the Atlantic stingray.

The mating season of the Atlantic stingray (Dasyatis sabina), which begins in August and continues through April, is the longest documented for any elasmobranch fish. Despite this protracted mating period, female stingrays ovulate synchronously at the end of the mating season and there is no evidence for sperm storage by females. Thus, the proximate causal factors and ultimate function of this extended preovulatory mating are unknown. Annual cycles of the gonadal steroids testosterone (T), dihydrotestosterone (DHT), 17beta-estradiol (E2), and progesterone (P4) were measured for 26 months in a wild estuarine population of Atlantic stingrays to test for associations with their reproductive biology, gametogenesis, and sexual behavior. Serum androgen levels in males showed four phases within an annual cycle: (1) androgen suppression between reproductive seasons (April-July), (2) primary androgen increase during the onset of spermatocyte development (August-October), (3) androgen decrease following maximum testis growth and spermatocyte development (November-December), and (4) secondary androgen increase during the peak of sperm maturation (January-March). Increases in male E2 and P4 were correlated with spermatocyte/spermatocyst formation, maximum testis weight, and the primary (but not secondary) androgen surge. We propose that the production of male androgens across the full seven-month preovulatory mating period promotes their aggressive reproductive behavior and drives the protracted mating season of this species. In females, serum T and DHT showed relatively brief increases near ovulation, whereas E2 and P4 showed brief increases near both ovulation and parturition. The increase in female androgens near ovulation may increase female aggression when they are impregnable by courting males and enhance their choice of mates. This estuary sample population shows higher absolute steroid levels and distinct differences in temporal cycles compared to another Florida fresh water lake population, but the cause and significance of these differences are unknown. Experiments are needed to confirm that the aggressive and protracted mating behavior is the result of prolonged male androgen production and to determine whether the sustained preovulatory mating serves some function related to female reproduction.

Differential distribution of gonadotropin-releasing hormone-immunoreactive neurons in the stingray brain: functional and evolutionary considerations.

Gonadotropin-releasing hormone (GnRH) is a neuropeptide that occurs in multiple structural forms among vertebrate species. Bony fishes, amphibians, reptiles, birds, and mammals express different forms of GnRH in the forebrain and endocrine regions of the hypothalamus which regulate the release of reproductive gonadotropins from the pituitary. In contrast, previous studies on bony fishes and tetrapods have localized the chicken GnRH-II (cGnRH-II) nucleus in the midbrain tegmentum and, combined with cladistic analyses, indicate that cGnRH-II is the most conserved form throughout vertebrate evolution. However, in elasmobranch fishes, the neuroanatomical distribution of cGnRH-II and dogfish GnRH (dfGnRH) cells and their relative projections in the brain are unknown. We used high-performance liquid chromatography and radioimmunoassay to test for differential distributions of various GnRH forms in tissues from the terminal nerve (TN) ganglia, preoptic area, and midbrain of the Atlantic stingray, Dasyatis sabina. These experiments identified major peaks that coelute with cGnRH-II and dfGnRH, minor peaks that coelute with lamprey GnRH-III (lGnRH-III), and unknown forms. Immunocytochemistry experiments on brain sections show that dfGnRH-immunoreactive (-ir) cell bodies are localized in the TN ganglia, the caudal ventral telencephalon, and the preoptic area. Axons of these cells project to regions of the hypothalamus and pituitary, diencephalic centers of sensory and behavioral integration, and the midbrain. A large, discrete, bilateral column of cGnRH-II-ir neurons in the midbrain tegmentum has sparse axonal projections to the hypothalamus and regions of the pituitary but numerous projections to sensory processing centers in the, midbrain and hindbrain. Immunocytochemical and chromatographic data are consistent with the presence of lGnRH-III and other GnRH forms in the TN that differ from dfGnRH and cGnRH-II. This is the first study that shows differential distribution of cGnRH-II and dfGnRH in the elasmobranch brain and supports the hypothesis of divergent function of GnRH variants related to gonadotropin control and neuromodulation of sensory function.