Behavioral biology最新文献

Albino rats from two outbred and three inbred strains received subcutaneous implants of either morphine or placebo pellets, followed by subcutaneous injections of naloxone hydrochloride, 0.4 mg/kg. The naloxone-precipitated opiate abstinence syndrome was observed 1, 2, or 3 days after implantation of the pellet. Fourteen behavioral and physiological responses were monitored before and after precipitated withdrawal. The strains differed in activity rate and in the number of escape attempts and wet-dog shakes which occurred prior to naloxone-precipitated withdrawal. The strains differed in activity rate and in the number of escape attempts and wet-dog shakes which occurred prior to naloxone-precipitated withdrawal. Further strain differences were evident following naloxone-precipitated withdrawal in spite of statistical correction for prenaloxone differences. The differences were most evident in the frequency of escape attempts, wet-dog shakes, teeth-chattering episodes, and activity counts. After naloxone injection, responding changed depending upon the length of exposure to the implanted morphine pellet in four of the strains observed; length of exposure did not affect the response profile of Holtzman rats significantly. This study confirms the assumption that differences between strains are significant in terms of their responses to opiates, and emphasizes the need to investigate these differences in further detail.

The effects of electroconvulsive shock on the estrous cycle in the rat were investigated. Sixty animals, chosen on the basis of stability of estrus, were assigned randomly to one of four treatment conditions with the restriction that each condition contain 15 subjects. Treatment conditions were as follows: one electroconvulsive shock; five electroconvulsive shocks; one sham electroconvulsive shock; and five sham electroconvulsive shocks. Results indicated that one electroconvulsive shock did not affect estrus, while five electroconvulsive shocks produced a significant delay in the onset of estrus. Once estrus began following a course of five shocks, no additional delays were observed.

A series of aliphatic acids and alcohols was isolated and identified from hamster vaginal discharge. These materials along with a previously identified hamster attractant pheromone, dimethyl disulfide, were assayed in amounts characteristic of a single female collection for their ability to attract normal males and to promote copulatory behavior toward female surrogates. Estrous hamster vaginal discharge attracted normal males and stimulated copulatory attempts toward scented surrogates. Male copulatory behavior was unmodified by: dimethyl disulfide, the aliphatic acids, the aliphatic alcohols or a grand mixture of all these identified components of vaginal discharge. Therefore there must be some, as yet unidentified, material in vaginal discharge which induces normal males to engage in copulatory behavior. Neither the acids nor the alcohols when presented as mixtures had significant effects on male attraction. The attractiveness of a grand mixture of dimethyl disulfide and the series of aliphatic acids and alcohols was comparable to the attractiveness of dimethyl disulfide alone. Thus, the presence of small amounts of dimethyl disulfide can account for much of the ability of whole vaginal discharge to attract males to the odor source even when this compound is assayed in the presence of large amounts of inactive biological odorants.

The role of exogenous hormones in mediating pacing of reproductive encounters by ovariectomized female rats was investigated. Five estradiol benzoate (EB) treatment groups (3.3, 10, 30, 60, or 90 μg/kg) were each given five weekly tests in a two-compartment escape-reentry mating arena in the presence of three sexually vigorous males. Prior to testing, each subject received one of four dosages of progesterone (P) (1, 2, 4, or 8 mg/kg) or oil. The mean time subjects spent in the escape compartment following an intromission or ejaculation decreased for all EB treatment groups as P levels increased. The percentage of intromissions followed by retreats to the escape compartment decreased similarly for all EB treatment groups as P increased. Lordosis response increased as a function of increasing levels of EB alone or in combination with increasing levels of P.

Male Wistar rats were divided into two groups maintained either on a normal lighting schedule with the 12-hr light period from 7 am to 7 pm, or on a reversed lighting schedule. The intake of water in response to ip injections of hypertonic saline or renin, given at 9 am, was found to be approximately equal for both groups, while drinking of a palatable 0.01 M saccharin solution was significantly greater for the group in the dark. The results suggest that the sensitivity of the primary thirst mechanisms does not vary during a 24-hr day, whereas those controlling secondary drinking are more responsive during the dark period. The relation of these observations to the circadian pattern of water intake in the rat is discussed.

Three experiments showed that domestic chicks reduce the relative intake of a colored solution that has been paired with sickness induced by lithium chloride. Learning occurred after only a single pairing and with a delay of up to 1 hr between the two events. The degree of initial reduction following conditioning depended on the poison dosage. These findings support the general notion that as a result of evolutionary processes the cues used in food selection are easily associated with sickness.

Previous experiments in several teleost species suggested that defensive reactions are increased following extensive bilateral ablation of the telencephalon. We investigated the effects of varied telencephalic lesions on the reaction of fish to handling and placement in an unfamiliar tank. When intact or sham-operated males were handled, they showed increased rates of surfacing for air. Males which were previously administered bilateral (TLX) or unilateral (UTLX) telencephalon ablation suppressed activity following handling. TLX lesions resulted in the greatest suppression reactions; in addition, the TLX males showed slightly decreased rates of activity prior to handling. Extensive, bilateral lesions of the dorsal telencephalon did not induce the suppression reaction in most males. Based on the results, we propose that one of the functions of the teleost telencephalon is to modulate defensive behavior. The structures which influence defensive behavior appear to be located in the ventral and possibly the rostrodorsal area of the telencephalon.

Durations of tonic immobility in back, side, front, and sit postures were collected from domestic and feral rabbits (Oryctolagus cuniculus), cottontail (Sylvilagus nuttalli), and hare (Lepus townsendi). The results suggest that there is a similarity in the immobility behavior displayed by the three genera of Leporidae. All of the animals would remain immobile when placed in the different postures. Overall durations of immobility were longer in the wild animals than in the domestic animals. Longest durations of immobility in rabbits occurred when they were placed in the back posture, while durations tended to be longer in cottontail and hare placed in the front posture. The wild animals also showed less spontaneous activity in the test situation than the domestic animals. The results seem consistent with the idea that immobility behavior in response to restraint might serve an anti-predator function.

Possible inhibitory effects of pregnancy upon the retention of maternal responsiveness in primiparous rats were examined by measuring behavioral latencies to respond to foster young in pregnant primiparous, nonpregnant primiparous, and virgin female rats. While high serum titers of progesterone associated with pregnancy are reported to inhibit rapid onset of maternal behavior in primigravid rats, findings in the present study demonstrate that the physiological state associated with a second pregnancy did not disrupt rapid reestablishment of maternal behavior. Specifically, 30–36 days after last exposure to their own young the median latencies to respond maternally to foster young ranged from 0.43 to 1.25 days for pregnant and nonpregnant primiparous rats. In contrast, virgin female rats with no prior maternal experience responded maternally significantly slower (median latencies: 4.33–4.75 days) than did primiparous females. These data suggest that after hormonal activation maternal responsiveness is retained independent of hormonal state.