Estradiol enhances the acquisition of lithium chloride-induced conditioned taste aversion in castrated male rats.

The present study examined the effects of short-term treatment with ovarian hormones on the acquisition of conditioned taste aversion (CTA). Adult male rats were castrated and randomly divided into LiCl- and saline-treated groups. Nineteen days after castration, all of the animals were subjected to 23.

Regional and subtype-specific loss of GnRH neurons is associated with diminished mating behavior in middle-aged male rats.

The current study was to examine the relationship between the number of gonadotropin-releasing hormone (GnRH) neurons and male sexual behavior in middle-aged rats. Based on their sexual performance, middle-aged male rats (18-19 months) were assigned to three groups: (i) Group MIE (showing mounts, intromissions, and ejaculation), (ii) Group MI (displaying mounts and intromissions, but no ejaculation), and (iii) Group NC (showing no copulatory behavior). The brains of these middle-aged animals and of sexually active, young controls were collected and then examined for immunohistochemical localization of GnRH neurons.

Different mechanisms of extinction of conditioned taste aversion are dependent on time intervals of extinction following conditioning.

After extinction, the reappearance of a conditioned response induced by an unconditioned stimulus which is weaker than that used during the conditioning training indicates that the extinction procedure does not eliminate the original conditioned memory. Recent studies on fear conditioning have shown that rats exhibited little or no recovery of conditioned responding if the time interval between fear acquisition and extinction was short, suggesting that the extinction process may erase the original conditioning trace in this situation. In the present study, a saving experiment was conducted in rats to investigate whether an aversive response could be recovered following extinction training with different time intervals after acquisition of conditioned taste aversion (CTA).

Ginkgo biloba extract treatment increases noncontact erections and central dopamine levels in rats: role of the bed nucleus of the stria terminalis and the medial preoptic area.

Rationale: Penile erection is necessary for successful copulation in males. The extract of Ginkgo biloba leaves (EGb 761) significantly facilitates copulation in male rats, but the effect of EGb 761 on noncontact erection (NCE) remains unknown.

Objective: The present study was conducted to evaluate the influence of EGb 761 on NCE in male rats.

Brief spatial experiences increase granule cell survival in the dentate gyrus of adult rats.

Rats of two experimental groups were placed in an open-field apparatus for 3-5 spatial exploration, each placement lasting 5min (total duration of 15-25min), and had a significantly greater newborn-neuron survival rate of the granule cells than the control group by evaluating the density of 5-bromo-2'deoxyuridine positive cells in the dentate gyrus. This study suggests that brief spatial experiences are sufficient to enhance the survival rate of newborn neurons.

Different subregions of the medial preoptic area are separately involved in the regulation of copulation and sexual incentive motivation in male rats: a behavioral and morphological study.

The purpose of this study was to investigate whether sexual incentive motivation and copulatory performance are regulated by different subregions of the medial preoptic area (MPOA). Sexual incentive motivation was measured by means of a partner preference test. Both copulatory behavior and sexual incentive motivation were tested in male rats treated with 50mg/kg of either EGb 761 or a vehicle (distilled water) by gavage for 14 days.

Effects of alcohol on the mouse-killing behavior of olfactory bulbectomized rats.

The purpose of the current study was to evaluate the effects of chronic administration of alcohol on the olfactory bulbectomy (OBX)-induced mouse-killing behavior (MKB), an animal model for screening antidepressants. The rats were divided into three groups, which were given alcohol (0, 0.5, or 1 g/kg/day) orally for 28 days.

Correlation of catecholamine levels in the bed nucleus of the stria terminalis and reduced sexual behavior in middle-aged male rats.

The correlation between dopamine (DA) and norepinephrine (NE) levels in the bed nucleus of the stria terminalis (BNST) and male sexual behavior was examined in middle-aged rats. Male rats (18-19 months) were divided into: (a) Group MIE, consisting of rats showing mounts, intromissions, and ejaculations; (b) Group MI, composed of rats showing mounts and intromissions, but no ejaculation; and (c) Group NC, consisting of noncopulators. Young adult rats (4-5 months) displaying complete copulatory behavior were used as the control.

Male sexual behavior and catecholamine levels in the medial preoptic area and arcuate nucleus in middle-aged rats.

The correlation between male sexual behavior and catecholamine levels in the medial preoptic area (MPOA) and arcuate nucleus (ARN) was studied in middle-aged rats. Male rats (18-19 months) were assigned to three groups: (1) Group MIE, consisting of rats showing mounts, intromissions, and ejaculations; (2) Group MI, consisting of rats showing mounts and intromissions, but no ejaculation; and (3) Group NC, consisting of non-copulators showing no sexual behavior. Young adult rats (4-5 months) displaying complete copulatory behavior were used as the control group.

Monoamine levels in the nucleus accumbens correlate with male sexual behavior in middle-aged rats.

The correlation between monoamine levels in the nucleus accumbens (NAcc) and male sexual behavior was studied in middle-aged rats. Male rats (18-19months) were assigned to three groups: (1) Group MIE consisted of rats showing mounts, intromissions, and ejaculations; (2) Group MI was composed of rats showing mounts and intromissions, but no ejaculation; and (3) Group NC were non-copulators showing no sexual behavior. Young adult rats (4-5months), displaying complete copulatory behavior, were used as the control group.

MK-801 suppresses muricidal behavior but not locomotion in olfactory bulbectomized rats: involvement of NMDA receptors.

In rats, olfactory bulbectomy (OBX) causes changes in glutamatergic function in the amygdala (AMG) and induces mouse-killing behavior (MKB). The medial AMG (mAMG) plays an important role in the initiation and maintenance of OBX-induced MKB. In the present study, systemic injection or intra-mAMG perfusion of (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801) was used to determine the effects of MK-801, a noncompetitive N-methyl-d-aspartate (NMDA) receptor antagonist, on the expression of OBX-induced MKB in male Wistar rats that had undergone OBX 1 month previously.

Effects of incisor-cutting on muricidal behavior induced by olfactory bulbectomy in rats.

Muricidal behavior in rats is composed of two main components, attacking and killing performance. Since a large number of mice could be killed by rats during behavioral experiments, research has been limited in the past decade possibly because of ethical considerations. In preliminary studies, we found that the rat incisors play a key role in muricidal behavior in rats, so, in the present study, we cut off the incisors and assessed the following parameters of muricidal behavior: attack latency, first attack site, lethal attack site, attack frequency, total attack duration and mean attack duration.