During the breeding season, the reproductive condition of female mammals changes. Females may or may not be sexually receptive. We conducted a series of experiments to determine whether reproductive condition of female meadow voles affects their scent marking behavior as well as the scent marking behavior of male conspecifics. In expt 1, females in postpartum estrus (PPE females) deposited more scent marks than females that were neither pregnant nor lactating (REF females) or ovariectomized females (OVX females). In expt 2, male voles scent marked more and deposited more over-marks in areas marked by PPE females than by REF and OVX females. In expt 3, PPE females deposited more scent marks and over-marks in areas marked by males than did females in the other reproductive states. The results of these experiments showed that male and female voles may vary in the number, type and location of scent marks they deposit in areas scented by particular conspecifics.

Abuse of Δ 9 -THC by females during adolescence may produce long-term deficits in complex behavioral processes such as learning, and these deficits may be affected by the presence of ovarian hormones. To assess this possibility, 40 injections of saline or 5.6 mg/kg of Δ 9 -THC were administered i.p. daily during adolescence to gonadally intact or ovariectomized (OVX) female rats, yielding 4 treatment groups (intact/saline, intact/THC, OVX/saline, and OVX/THC). Δ 9 -THC (0.56-10 mg/kg) was then re-administered to each of the 4 groups during adulthood to examine their sensitivity to its disruptive effects. The behavioral task required adult subjects to both learn (acquisition component) different response sequences and repeat a known response sequence (performance component) daily. During baseline (no injection) and control (saline injection) sessions, ovariectomized subjects had significantly higher response rates and lower percentages of error in both behavioral components than the intact groups irrespective of saline or Δ 9 -THC administration during adolescence; the intact group that received Δ 9 -THC had the lowest response rates in each component. Upon re-administration of Δ 9 -THC, the groups that received adolescent ovariectomy alone, adolescent Δ 9 -THC administration alone, or both treatments were found to be less sensitive to the rate-decreasing effects, and more sensitive to the error-increasing effects of Δ 9 -THC than the control group (i.e., intact subjects that received saline during adolescence). Neurochemical analyses of the brains from each adolescent-treated group indicated that there were also persistent effects on cannabinoid type-1 (CB-1) receptor levels in the hippocampus and striatum that depended on the brain region and the presence of ovarian hormones. In addition, autoradiographic analyses of the brains from adolescent-treated, but behaviorally-naïve, subjects indicated that ovariectomy and Δ 9 -THC administration produced effects on receptor coupling in some of the same brain regions. In summary, chronic administration of Δ 9 -THC during adolescence in female rats produced long-term effects on operant learning and performance tasks and on the cannabinoid system that were mediated by the presence of ovarian hormones, and that altered their sensitivity to Δ 9 -THC as adults.

Observations of numerous mammals suggest males self‐groom more than females in response to the odours of opposite‐sex conspecifics. Two experiments tested the hypothesis that self‐grooming may be a tactic used by males to attract mates in prairie voles Microtus ochrogaster. In the first experiment, we measured the amounts of time voles self‐groomed during exposure either to male‐scented cotton bedding, female‐scented cotton bedding, or clean cotton bedding. Results from this experiment support the hypothesis and also show that female prairie voles self‐groom in response to odours of males. In addition, male prairie voles groom more in response to male odours than to female odours, suggesting that self‐grooming also serves a role in male–male competition. In the second experiment, male and female voles spent more time investigating scent marks of opposite‐sex conspecifics that recently self‐groomed at a higher rate than those of opposite‐sex conspecifics that self‐groomed at a lower rate. Female, but not male prairie voles, spent more time investigating scent marks of opposite‐sex conspecifics that self‐groomed at a high rate than those of same‐sex conspecifics that self‐groomed at a high rate. For prairie voles, self‐grooming may increase the detection of their scent marks by conspecifics. By self‐grooming, prairie voles may be attempting to attract opposite‐sex conspecifics, and males may also be attempting to deter encounters with male conspecifics.

Although Δ9-THC has been approved to treat anorexia and weight loss associated with AIDS, it may also reduce well-being by disrupting complex behavioral processes or enhancing HIV replication. To investigate these possibilities, four groups of male rhesus macaques were trained to respond under an operant acquisition and performance procedure, and administered vehicle or Δ9-THC before and after inoculation with simian immunodeficiency virus(SIVmac251, 100 TCID50/ml, i.v.). Prior to chronic Δ9-THC and SIV inoculation, 0.032– 0.32 mg/kg of Δ9-THC produced dose-dependent rate-decreasing effects and small, sporadic error-increasing effects in the acquisition and performance components in each subject. Following 28 days of chronic Δ9-THC (0.32 mg/kg, i.m.) or vehicle twice daily, delta-9-THC-treated subjects developed tolerance to the rate-decreasing effects, and this tolerance was maintained during the initial 7–12 months irrespective of SIV infection (i.e., +THC/−SIV, +THC/+SIV). Full necropsy was performed on all SIV subjects an average of 329 days post-SIV inoculation, with postmortem histopathology suggestive of a reduced frequency of CNS pathology as well as opportunistic infections in delta-9-THC-treated subjects. Chronic Δ9-THC also significantly reduced CB-1 and CB-2 receptor levels in the hippocampus, attenuated the expression of a proinflammatory cytokine (MCP-1), and did not increase viral load in plasma, cerebrospinal fluid, or brain tissue compared to vehicle-treated subjects with SIV. Together, these data indicate that chronic Δ9-THC produces tolerance to its behaviorally disruptive effects on complex tasks while not adversely affecting viral load or other markers of disease progression during the early stages of infection.

Many terrestrial mammals scent mark in areas containing the scent marks of conspecifics, and thus, may deposit their own scent marks on top of those that were deposited previously by conspecifics. This phenomenon, known as over-marking appears to play a role in same-sex competition or mate attraction. The present study determines whether meadow and prairie voles avoid over-marking the scent marks of conspecifics, target the scent marks of conspecifics and over-mark them, or randomly over-mark the scent marks of conspecifics. The data show that meadow and prairie voles adjust the number and location of scent marks that they deposit in areas marked previously by particular conspecifics. Male and female meadow and prairie voles target the scent marks of opposite-sex conspecifics and over-mark them. Female meadow and prairie voles also target the scent marks of female conspecifics. In contrast, male meadow and prairie voles over-mark the scent marks of male conspecifics in a random manner. By differentially overmarking the scent marks of conspecifics, voles may be able to communicate particular information to a variety of conspecifics.

Background-Adolescent alcohol use may contribute to long-term changes in the receptors and neuroactive steroids that may mediate its effects and to subsequent alcohol abuse and dependence as an adult. Therefore, in the present study, ethanol preference and intake as an adult were examined after adolescent ethanol or saline administration. In addition, ethanol intake in the same groups was examined after administration of two neuroactive steroids with modulatory effects at GABA A receptors.

No abstract

No abstract