The scheduling of adolescence with Netrin-1 and UNC5C.

Dopamine axons are the only axons known to grow during adolescence. Here, using rodent models, we examined how two proteins, Netrin-1 and its receptor, UNC5C, guide dopamine axons towards the prefrontal cortex and shape behaviour. We demonstrate in mice ( Mus musculus ) that dopamine axons reach the cortex through a transient gradient of Netrin-1 expressing cells - disrupting this gradient reroutes axons away from their target. Using a seasonal model (Siberian hamsters; Phodopus sungorus ) we find that mesocortical dopamine development can be regulated by a natural environmental cue (daylength) in a sexually dimorphic manner - delayed in males, but advanced in females. The timings of dopamine axon growth and UNC5C expression are always phase-locked. Adolescence is an ill-defined, transitional period; we pinpoint neurodevelopmental markers underlying this period.

Time to drink: Activating lateral hypothalamic area neurotensin neurons promotes intake of fluid over food in a time-dependent manner.

The lateral hypothalamic area (LHA) is essential for ingestive behavior but has primarily been studied in modulating feeding, with comparatively scant attention on drinking. This is partly because most LHA neurons simultaneously promote feeding and drinking, suggesting that ingestive behaviors track together. A notable exception are LHA neurons expressing neurotensin (LHANts neurons): activating these neurons promotes water intake but modestly restrains feeding. Here we investigated the connectivity of LHANts neurons, their necessity and sufficiency for drinking and feeding, and how timing and resource availability influence their modulation of these behaviors. LHANts neurons project broadly throughout the brain, including to the lateral preoptic area (LPO), a brain region implicated in modulating drinking behavior. LHANts neurons also receive inputs from brain regions implicated in sensing hydration and energy status. While activation of LHANts neurons is not required to maintain homeostatic water or food intake, it selectively promotes drinking during the light cycle, when ingestive drive is low. Activating LHANts neurons during this period also increases willingness to work for water or palatable fluids, regardless of their caloric content. By contrast, LHANts neuronal activation during the dark cycle does not promote drinking, but suppresses feeding during this time. Finally, we demonstrate that the activation of the LHANts â†’ LPO projection is sufficient to mediate drinking behavior, but does not suppress feeding as observed after generally activating all LHANts neurons. Overall, our work suggests how and when LHANts neurons oppositely modulate ingestive behaviors.

Friends-Based Protective Strategies and Unwanted Sexual Experiences: A Daily Diary Examination of First Year College Women.

Risk for unwanted sexual experiences can emerge in social contexts-the same contexts that early college women navigate with their friends. Though friends naturally engage in prevention strategies, less is known about how capable guardianship influences risk. Using multilevel structural equation modeling, the present study examined guardianship at the person- and situation-level. First year college women (N = 132) completed eight weekends of daily surveys. We examined whether guardianship (e.g., more friends present, greater proportion of female friends, no intoxicated friends) would reduce unwanted sexual experience risk and if this relation was mediated by friends-based strategy use. An alternative model was also tested with the same predictors, but unwanted sexual experiences as the mediator and friends-based strategy use as the outcome. Over half (58%) of extended weekend nights with friends involved drinking or using drugs. Friends-based strategies were used on 29% of nights. Across models, being with one or more intoxicated friends was associated with friends-based strategy use and an unwanted sexual experience, but only at the situation-level. Parents, educators, and policy makers can encourage college women to draw on their social networks to enhance safety. Interventions could incorporate more universal strategies for responding to risk in social contexts.

A Qualitative Study on Friends and the Social Context of Sexual Victimization: Implications for Campus-Based Interventions.

Sexual victimization (SV) risk can begin in social contexts, ones where friends are present, though it is unclear how friends might be integrated into SV prevention. Using focus groups, female college drinkers described (a) the role of friends in preventing SV, (b) the strategies friends use to reduce vulnerability, and (c) the barriers to implementation. Friends-based strategies (keeping tabs on one another, using signals to convey potential danger, interrupting escalating situations, taking responsibility for friends, relying on male friends) and barriers (intoxication, preoccupation, situation ambiguity, social consequences) were discussed. Interventions can draw on these strategies, but must address the critical barriers.

High-fat diet alters fluid intake without reducing sensitivity to glucagon-like peptide-1 receptor agonist effects.

Rats that are maintained on a high-fat diet (HFD) differ from controls in many ways, but how HFD maintenance affects water intake and drinking behavior has not been well studied. This is unfortunate because diet and obesity may influence fluid balance in humans through a mechanism that is poorly understood. We therefore tested the hypothesis that HFD maintenance affects water intake in rats. Water intake and drinking behavior are, in part, controlled by the actions of glucagon-like peptide-1 (GLP-1), a peptide which is well studied for its hypophagic effects. Previous studies have shown that HFD maintenance impairs the ability of GLP-1 receptor agonists to suppress food intake when the drug is administered peripherally, but not centrally. The effects of GLP-1 on fluid intake are thought to rely more on central receptor activation; therefore, a secondary aim of these experiments was to shed additional light on the location of GLP-1 responsive cells that mediate feeding vs drinking behavior. We maintained male Sprague-Dawley rats on HFD or low-fat diet (LFD) for six weeks and measured body weight, food intake, water intake, and drinking behavior. We then tested the relative contributions of diet and body weight on food intake and water intake after peripheral and central injections of GLP-1 receptor agonist Exendin-4 (Ex4). We found that HFD maintenance reduced the amount of water consumed, when intake was corrected for body weight. Consistent with other reports, rats on HFD showed a smaller suppression of food intake when given Ex4 peripherally, but not centrally. Water intake suppression when given Ex4 did not differ by diet or body weight regardless of injection site, however, adding support to the hypothesis that only central GLP-1 receptors are involved in water intake.