Disrupting the endocannabinoid system in early adolescence negatively impacts sociability.

Animal models suggest that the endocannabinoid system (eCS) helps regulate various aspects of social behavior, including play behavior and social reward, during adolescence. Properly tuned endocannabinoid signaling may be a critical developmental component in the emergence of normal adult sociability. In the current experiment, we attempted to pharmacologically disrupt endocannabinoid tone during early adolescence, and then measure the behavioral effects at two subsequent time points. 36 male and 36 female Long Evans rats received daily injections of one of three treatments between post-natal day (PND) 25-39: 1) vehicle treatment, 2) 0.4 mg/kg CP55,940 (a potent CB1/CB2 receptor agonist), or 3) 0.5 mg/kg AM251 (a CB1 receptor antagonist/inverse agonist). Both soon after treatment (PND 40-44) and several weeks later (PND 66-70), subjects were tested in an elevated plus maze (EPM) for anxiety and in a three-chambered apparatus for sociability. For the latter test, the number of entries into each chamber and the amount of time spent investigating each target were measured. Analyses revealed significant main effects of both sex and age on sociability: males expressed greater sociability compared to females, and sociability was higher in adolescence than adulthood. Most importantly, drug treatment (both CP55,940 and AM251) attenuated sociability in adolescence without having a significant effect on anxiety in the EPM. However, this effect did not persist into adulthood. These results indicate that pharmacological disruption of endocannabinoid tone - through either chronic agonism or antagonism of cannabinoid receptors - during early adolescence has a detrimental effect on sociability. This effect may be caused by transient, compensatory alterations in the eCS.

Assessing the role of serotonergic receptors in cannabidiol's anticonvulsant efficacy.

Cannabidiol (CBD) is a phytocannabinoid that has demonstrated anticonvulsant efficacy in several animal models of seizure. The current experiment validated CBD's anticonvulsant effect using the acute pentylenetetrazol (PTZ) model. Furthermore, it tested whether CBD reduces seizure activity by interacting with either the serotonergic 5HT1A or 5HT2A receptor. 120 male adolescent Wistar-Kyoto rats were randomly assigned to 8 treatment groups in two consecutive experiments. In both experiments, subjects received either CBD (100mg/kg) or vehicle 60min prior to seizure testing. In Experiment 1, subjects received either WAY-100635 (1mg/kg), a 5HT1A antagonist, or saline vehicle injection 80min prior to seizure testing. In Experiment 2, subjects received either MDL-100907 (0.3mg/kg), a specific 5HT2A antagonist, or 40% DMSO vehicle 80min prior to seizure testing. 85mg/kg of PTZ was administered to induce seizure, and behavior was recorded for 30min. Seizure behaviors were subsequently coded using a 5-point scale of severity. Across both experiments, subjects in the vehicle control groups exhibited high levels of seizure activity and mortality. In both experiments, CBD treatment significantly attenuated seizure activity. Pre-treatment with either WAY-100635 or MDL-100907 did not block CBD's anticonvulsant effect. WAY-100635 administration, by itself, also led to a significant attenuation of seizure activity. These results do not support the hypothesis that CBD attenuates seizure activity through activation of the 5HT1A or 5HT2A receptor. While this work further confirms the anticonvulsant efficacy of CBD and supports its application in the treatment of human seizure disorders, additional research on CBD's mechanism of action must be conducted.

The effects of adolescent cannabinoid exposure on seizure susceptibility and lethality in adult male rats.

There is substantial evidence in rodent models that chronic exposure to cannabinoids during adolescence can alter the development of neurobiological systems that are implicated in regulating brain activity and seizure. The current study explored whether adolescent cannabinoid treatment affects subsequent, adult seizure susceptibility. Sixty male Wistar Kyoto rats were treated with either the synthetic cannabinoid, CP 55,940 (0.4mg/kg, one treatment per day), or vehicle between 35 and 45days old. Subjects were then allowed to mature to adulthood. At 68-69days of age, subjects were tested for seizure susceptibility using the pro-convulsant, pentylenetetrazol (PTZ). Subjects received an acute injection of either 35mg/kg or 50mg/kg PTZ immediately prior to a 30-min behavioral seizure test. PTZ doses were chosen to produce low-to-moderate levels of seizure activity in control subjects. There were no significant differences between treated and control subjects in: latency to first seizure, mean seizure severity, percentage who displayed any seizure activity, percentage who displayed clonic seizure, or percentage who displayed tonic-clonic seizure. However, CP 55,940-treated subjects had a higher mortality rate compared to controls at both PTZ doses, suggesting that adolescent cannabinoid exposure may increase the lethality of severe seizures experienced in adulthood.

Adolescent cannabinoid treatment negatively affects reproductive behavior in female rats.

Sex differences in the neurobehavioral effects of chronic cannabinoid exposure suggest that gonadal hormones may modify cannabinoid activity. The current experiment assessed the impact of combined cannabinoid and estradiol treatment in ovariectomized, adolescent female rats on subsequent adult sexual behavior. Female Long-Evans rats were administered daily injections of either the cannabinoid agonist, CP 55,940 (0.4 mg/kg), or vehicle from post-natal day (PND) 40-49. Half of each treatment group also received daily injections of estradiol (50 µg/kg) or sesame oil vehicle from PND 39-49. Beginning on PND 74, subjects' reproductive behavior, including receptivity, proceptivity, and pacing, was assessed via a fifteen-minute paced mating test. There were significant main effects of estradiol treatment on rate of hop-darts emitted, number of arena crossings, and ejaculations received during the paced mating test. Overall, estradiol-treated females produced higher and more typical levels of sexual behavior. There were significant interactions between hormone and cannabinoid treatment on lordosis quotient, percentage of exits following male sexual stimulation, and contact-return latency for intromissions. Adolescent cannabinoid treatment detrimentally impacted the display of female receptivity and pacing, but only within estradiol-treated subjects. We discuss possible interpretations of these results, including potential mechanisms by which adolescent cannabinoid exposure might disrupt the normal development of female reproductive behavior.

Adolescent cannabinoid exposure attenuates adult female sexual motivation but does not alter adulthood CB1R expression or estrous cyclicity.

Adolescence is a developmental period characterized by neuronal remodeling and the maturation of adult emotionality, reproductive behavior and social behavior. We examined whether chronic cannabinoid exposure in adolescent rats alters female sexual motivation, estrous cyclicity, sucrose preference, and CB(1)R expression in adulthood. Female rats were administered with the synthetic cannabinoid agonist, CP-55,940 (0.4 mg/kg, intraperitoneal), daily during adolescent development (PND 35-45). In a subset of subjects, socio-sexual motivation was investigated in adulthood (PND 75-86) using a runway apparatus. Estrous cyclicity was tracked in adulthood via vaginal cytology and a single-mount test. A two-bottle sucrose preference test was also conducted to determine whether predicted changes in socio-sexual motivation might be linked to alterations in hedonic processing. CB(1)R expression was examined in two separate subsets of subjects, one sacrificed following drug treatment (PND 46) and one before behavioral testing (PND 74). Drug treatment significantly decreased adult preference for a male conspecific (sexual motivation), as assessed by both Run Time and Proximity Time, but did not affect estrous cyclicity or sucrose preference. CP-55,940 treatment also induced immediate, but transient, decreases in CB(1)R expression in the ventromedial nucleus of the hypothalamus and amygdala. Drug treatment did not affect CB(1)R expression in the nucleus accumbens (core or shell) or globus pallidus at either time point. We suggest that the endocannabinoid system may play a role in the maturation of neuroendocrine axes and adult female reproductive behavior, and that chronic exposure to cannabinoids during adolescence disrupts these neurodevelopmental processes.

Acute cannabinoid administration attenuates female socio-sexual motivation.

Endocannabinoids may normally inhibit the generation and expression of female estrous behaviors. Previous work in our laboratory demonstrated that acute administration of a CB(1) receptor antagonist (AM251) increased sexual incentive motivation in estrous female rats. The current experiment examined the effect of CP55,940, a synthetic cannabinoid agonist, on sexual motivation. Seventy-two ovariectomized female Long-Evans rats were tested for their socio-sexual motivation via a runway methodology. Baseline motivation to approach and maintain close proximity to an empty goalbox, a female conspecific, and a male conspecific was assessed over six trials. Subjects were then grouped into nine experimental conditions and re-tested for their socio-sexual motivation after one of three possible hormonal treatments and three drug doses. Hormone treatments were: oil (nonestrous), 10 microg estradiol benzoate (partially estrous), and 10 microg estradiol+500 microg progesterone (fully estrous). Drug doses were: 0, 20, or 40 microg/kg CP55,940 (IP, 30 min prior to testing). As expected, hormonal priming with both estradiol and progesterone significantly increased sexual motivation in females that did not receive drug treatment. This occurred even though females were kept sexually-naïve throughout the experiment. CP55,940 dose-dependently attenuated sexual motivation for a male target in estrous females; the 40 microg/kg dose completely blocked sexual motivation. However, this same dose also significantly reduced social motivation for another female. Cannabinoid agonists reduce female sexual motivation, either directly by inhibiting estrus or indirectly by increasing social anxiety.

Cannabinoid-hormone interactions in the regulation of motivational processes.

There is a bi-directionality in hormone-cannabinoid interactions: cannabinoids affect prominent endocrine axes (such as the hypothalamic-pituitary-gonadal), and gonadal hormones modulate cannabinoid effects. This review will summarize recent research on these interactions, with a specific focus upon their implications for motivated behavior. Sexual behavior will serve as a "case study." I will explore the hypothesis that ovarian hormones, in particular estradiol, may serve to release estrous behavior from endocannabinoid inhibition. Hormonal regulation of the endogenous cannabinoid system also affects processes that underlie drug abuse. This review will briefly discuss sex differences in behavioral responses to cannabinoids and explore potential mechanisms by which gonadal hormones alter cannabinoid reward. An examination of this research informs our perspective on how hormones and endocannabinoids may affect drug-seeking behavior as a whole and the development of addiction.

Attractive men induce testosterone and cortisol release in women.

Recently, Roney et al. (Roney, J.R., Lukaszewski, A.W., Simmons, Z.L., 2007. Rapid endocrine responses of young men to social interactions with young women. Horm. Behav. 52, 326-33; Roney, J.R., Mahler, S.V., Maestripieri, D., 2003. Behavioral and hormonal responses of men to brief interactions with women. Evol. Hum. Behav. 24, 365-375) demonstrated that men release testosterone and cortisol in response to brief social interactions with young women. The current experiment examined whether women show a similar endocrine response to physically and behaviorally attractive men. 120 women (70 naturally-cycling and 50 using hormonal contraceptives) were shown one of four 20-minute video montages extracted from popular films, depicting the following scenarios: 1) an attractive man courting a young woman (experimental stimulus), 2) a nature documentary (video clip control), 3) an unattractive older man courting a woman (male control), and 4) an attractive woman with no men present (female control). Saliva samples were taken before and after presentation of the stimulus, and were later analyzed for testosterone and cortisol content via enzyme immunoassay. Naturally-cycling women experienced a significant increase in both testosterone and cortisol in response to the experimental stimulus but to none of the control stimuli. Participants taking hormonal contraceptives also showed a significant cortisol response to the attractive man. Women may release adrenal steroid hormones to facilitate courtship interactions with high mate-value men.

Cannabinoid receptor antagonism increases female sexual motivation.

The current experiments examined whether treatment with a CB1 antagonist/inverse agonist (AM251) affects sexual motivation, proceptivity, and receptivity in female rats. In experiment #1, 92 Long-Evans rats were tested for their socio-sexual motivation via a runway methodology. Motivation to approach and maintain close proximity to an empty goalbox, a female, and a male target was assessed following hormonal and drug treatment. Hormone treatments were: oil vehicle, 10 microg estradiol, and 10 microg estradiol+500 microg progesterone. Drug doses were 0, 2, and 4 mg/kg AM251 (IP, 60 min prior to testing). In experiment #2, 32 female subjects were tested for receptivity and proceptivity in a paced mating chamber. Subjects were given either a high (10 microg estradiol+500 microg progesterone) or low dose of hormones (2 microg estradiol+250 microg progesterone), and either vehicle or 2 mg/kg AM251. AM251 significantly increased sexual motivation for a male target in the runway in females primed with both estradiol and progesterone. AM251 also enhanced lordosis (in low hormone females) and increased hop-darts. These findings suggest that endocannabinoids tonically inhibit estrous behaviors. Cannabinoid antagonists could serve as new treatment option for women suffering from abnormally low libido.

The effects of sexual experience and estrus on male-seeking motivated behavior in the female rat.

Ovariectomized (OVX) female rats were trained to traverse a straight alley and return to a goal box where they had previously encountered a male rat, a female rat or an empty goal box. The time required to run the alley was used as an index of the subjects' motivation to re-engage the goal box target. Subjects were tested in both estrus and non-estrus, first sexually naïve and then again after sexual experience. Female rats ran most quickly for a male target, most slowly for an empty goal box, and at intermediate speeds for a female target. Sexual experience tended to slow run times for all but male targets. Estrus enhanced approach behavior for males and an empty goal box, but tended to slow the approach toward females, both before and after sexual experience. This latter finding was further investigated in a second experiment in which sexually naïve OVX females were tested during estrus and non-estrus in a locomotor activity apparatus, a runway with an empty goal box, and an open field. Estrus produced no changes in spontaneous locomotion either in the activity box or the open field, but decreased run times in the alley and increased the number of center-square entries in the open-field. Thus, estrus produces increases in sexual motivation that selectively enhance exploratory, presumably male-seeking behavior, but not simple spontaneous locomotion.

The effect of acute bupropion on sexual motivation and behavior in the female rat.

Recent clinical studies have suggested that the atypical antidepressant, bupropion (Wellbutrin), may stimulate sexual desire in women. Two experiments were conducted, testing the effect of acute bupropion administration on the sexual motivation and copulatory behavior of female rats. In the first experiment, 63 sexually-experienced, female Long-Evans rats were tested in a runway for their motivation to approach an empty goalbox, a nonestrous female, and an adult male. Both latency to approach and time spent in close proximity to the targets were used as dependent variables. Subjects were tested in both a nonestrous (OVX) and estrous (OVX+15 microg estradiol+500 microg progesterone) state, and following administration of 0.0, 7.5, or 15 mg/kg bupropion hydrochloride (subcutaneous, 45 min prior to testing). Results indicated that pre-treatment with ovarian hormones significantly increased the sexual motivation of the subjects. Bupropion treatment had no significant effect, either stimulatory or inhibitory, on subjects' socio-sexual motivation. In the second experiment, 60 female subjects were paired with an adult male for a thirty-minute copulatory test. Subjects were tested under one of three hormonal conditions: nonestrous (no hormones), 15 mug estradiol, or 15 microg estradiol+500 microg progesterone. Subjects were also pre-treated with either physiological saline or 15 mg/kg bupropion. Results indicated that while hormonal administration had a strong effect on female sexual behavior, bupropion treatment did not significantly affect either lordosis or the emission of hop-darts. Males paired with bupropion-treated females successfully achieved a greater number of ejaculations and demonstrated significantly shortened post-ejaculatory intervals. It is possible that bupropion treatment enhanced female attractiveness.

Stressful experiences in children and adolescents: initial report from the PSEI-NCPV Honolulu Study.

As part of a federal study on the biology of stress and resilience, a comprehensive, structured stress-history interview (PSEI-NCPV) was administered to 307 participants recruited in Honolulu. A moderate correlation between childhood stress and current depression was found. A relatively high rate of "severe bullying/hazing," and a high mean stress-intensity rating for "blood-drawing induced anxiety" call for further research.

Evidence based complementary intervention for insomnia.

Increasing scientific evidence point to a non-pharmacological complementary treatment for insomnia: white noise. Its presentation has been shown to induce sleep in human neonates and adults, probably by reducing the signal-to-noise ratio of ambient sound. White noise may be a simple, safe, cost-effective alternative to hypnotic medication in many psychiatric disorders, especially acute stress disorder and PTSD.

Exposure to female rats produces differences in c-fos induction between sexually-naïve and experienced male rats.

Sexual incentive-induced Fos-like immunoreactivity (Fos-Li) within six neural regions implicated in male sexual behavior was investigated in both sexually-naïve and experienced male rats. Sexual experience was limited to one copulation culminating in ejaculation 24 h prior to testing. On test-day, subjects were placed within a cylindrical arena for 15 min on the opposite side of a perforated, Plexiglas partition from one of three targets: an uninhabited area, a non-estrous female, or an estrous female. Then 1 h later, each subject was sacrificed and its brain prepared for subsequent immunocytochemical staining. Analyses revealed a main effect of target stimulus on c-fos expression within the nucleus accumbens shell and core of male subjects. In addition, sexually-experienced subjects demonstrated significantly more Fos-Li within the nucleus accumbens shell in response to an estrous female versus a non-estrous female. There was also greater estrous cue-induced Fos-Li in the nucleus accumbens shell of experienced subjects when compared to naïve subjects. These data support previous suggestions implicating the nucleus accumbens in the generation of male sexual motivation. In addition, copulatory experience, even when limited to one ejaculation, seems to mediate long-term changes in the response properties of nucleus accumbens neurons that may reflect the value enhancement of primary female incentives.

Sexually conditioned incentives: attenuation of motivational impact during dopamine receptor antagonism.

The motivational impact of sexually conditioned incentives was examined in two experiments. In Experiment 1, male Long-Evans rats copulated to ejaculation in the presence of one of two scents (orange or almond extract) on five separate occasions. On alternating days, subjects spent an equal amount of time in social isolation with the opposing scent. Following the 10-day conditioning regimen, subjects ran more rapidly down an operant runway toward a goalbox containing the sex-paired scent (CS+) compared to trials on which the isolation-paired scent (CS-) or no scent was provided. In Experiment 2, comparably conditioned male rats were first given a baseline runway trial with an unscented goalbox. The following day, subjects were pretreated with one of four doses of haloperidol (0.0, 0.075, 0.15, or 0.30 mg/kg i.p.) 45 min prior to being tested in the runway for their motivation to approach either the CS+ or CS- scents. Control subjects given vehicle injections performed comparably to subjects from Experiment 1, taking significantly less time to approach the CS+ than an unscented goalbox. This decrease in run latency was not observed in subjects within the 0.075 and 0.15 mg/kg haloperidol groups. Subjects in the 0.30 mg/kg haloperidol groups took significantly more time to approach both the CS+ and CS- compared to their baseline run times. These data reveal that an olfactory cue associated with sexual reward becomes a conditioned incentive capable of eliciting approach behavior, and that dopamine receptor antagonism (at moderate but not high doses) selectively attenuates this cue-induced motivation.