Behavioral biology最新文献

Male rats injected with androstenedione (AD) during pre- and/or neonatal development showed normal patterns of sexual behavior in adulthood. Although both prenatal AD and postnatal AD significantly decreased testes weight, AD did not inhibit normal development of peripheral accessory sex organs. Prenatal AD enhanced prostate and seminal vesicles weight. The data challenge previous suggestions that exposure during fetal life to high levels of androgen, in general, and AD, in particular, inhibits the course of normal sexual differentiation in the male rat.

The results of two experiments are reported in which animals were simultaneously tested for locomotion and exploration after systemic injections of dopaminergic agonists. The testing apparatus was an open field in which 16 holes were made in the floor. Locomotion was measured by movement in the open field. Exploration was measured by investigation of the holes in the floor. In the first experiment the effects of apomorphine and ET 495 at three dose levels were compared in male rats that had been adapted to the testing situation for 21 days. In these animals, both drugs reduced exploration but only apomorphine reduced locomotion. In the second experiment, male and female rats with little prior experience in the apparatus were tested under three doses of apomorphine. In general the females were more sensitive to the drug, showing decreases in exploration at lower doses than did the males. Furthermore, the apomorphine failed to reduce locomotor activity in either sex except under the highest dose of apomorphine used (10 mg/kg) at which time stereotyped behavior was frequently observed.

Spontaneously hypertensive (SHR) and normotensive (WKY) male rats were transferred daily for 4 consecutive days from their home cages to a shock chamber and, after 5 min, received 60 footshocks (2.5 mA, 0.4 sec in duration, every 5 sec). Control animals of each strain were handled in the same manner but were never shocked. Blood samples were obtained from each rat on the fifth day via a chronic, indwelling tail arterial catheter. Previous exposure to footshock had no effect on plasma levels of norepinephrine (NE) and epinephrine (EPI) while animals were undisturbed in their home cages. After transfer to the shock chamber, the increases in plasma levels of NE and EPI were greater in previously shocked SHR than in unshocked SHR or shocked WKY rats. In addition, the increase in heart rate associated with transfer to the shock chamber was greater in previously shocked SHR rats than in unshocked SHR or in WKY controls. Previously shocked animals of both strains were also less active and defecated more frequently than controls when placed into the shock chamber. These results indicate that SHR and WKY rats have similar behavior responses to anticipation of footshock, but only in SHR rats is this attended by enhanced adrenergic responsivity.

The activity and sleep of six male and six female wild trapped eastern chipmunks, Tamias striatus, were observed in small simple cages and larger more complex aquaria. The animals were observed for 24 consecutive hr, and their behavior was categorized into one of six mutually exclusive categories. The results show that the circadian placement of sleep was modified by alterations in enclosure size and complexity, while percentage of time asleep and all measures of activity were unaltered.

Observations were made of approximately 60 adult male and female Sarotherodon (Tilapia) mossambicus. Males residing with females (unlimited contact) displayed significantly more than males in aquaria adjacent to females with only visual contact. In addition, unlimited contact males showed increased courting prior to female oviposition, whereas males with only visual contact exhibited little change in courting frequency throughout the interval between spawnings. Changes in chemical stimuli broadcast by females could account for the results, but other nonvisual modes could be important, especially under field conditions.

Swiss—Webster mice were reared in litters composed of six males, six females, or five females and one male. Maternal and pup behaviors were observed prior to weaning and recorded by checklist using the instantaneous scan method. Some preweaning social behaviors occurred earlier among pups in the mixed litters than in litters of one sex. No differences in maternal behavior were observed. The males were tested for aggressiveness at 60–65 days of age by caging them in groups of four, two each from all-male and single-male litters, for a period of 6 days. Aggressiveness ranks were assigned within each cage on the basis of body scars and behavioral observation. It was found that males reared as the single male in the litter engaged in more intermale aggression than those from all-male litters. Aggressiveness was also highly related to weight loss during the group housing period, the most aggressive animals losing the least weight. The preweaning environment affects later intermale aggression in mice, perhaps by way of intralitter social interactions, olfactory cues, or hormonal levels.

Effects of testosterone alone and in combination with progesterone on investigatory preferences, fighting, and olfaction in castrated male CD-1 mice were assessed. Testosterone stimulated both preferences for intact male mice and aggression, while progesterone reduced attention to intact male mice and reduced aggression. Accessory sex tissue weights and olfactory ability were unaffected by progesterone treatment. The possibility of a centrally located antagonism of testosterone by progesterone exclusive of the olfactory system is discussed.

Adult male and female Sprague—Dawley rats were assayed for olfactory preference of various sulfur-containing compounds. Both sexes preferred dimethyl disulfide. Male rats were also interested in dimethyl sulfite and hexyl mercaptan odor, while females preferred methyl isothiocyanate. The three latter compounds were found to be present in rat preputial gland volatiles and may aid in sex recognition.

The present experiments show that desoxycorticosterone-, aldosterone-, and furosemide-induced sodium deficiency will elicit a sodium appetite in rats raised either on a high sodium diet or on a normal sodium diet. Rats were injected for 2 consecutive days with either desoxycorticosterone (5.0 or 10.0 mg/100 g body weight), aldosterone (0.5 and 0.75 mg/100 g body weight), and furosemide (10.0 mg/100 g body weight). The results provide evidence against the theory that mineralocorticoid-induced sodium appetite is contingent upon prior associations between body sodium deficiency and elevated endogenous mineralocorticoid levels.

Rats allowed to consume a glucose/saccharin mixture for 30 min prior to each experimental session failed to acquire schedule-induced polydipsia when compared to rats allowed only water during this period. Further, if rats that had developed schedule-induced polydipsia were allowed access to the glucose/saccharin mixture prior to each experimental session, their schedule-induced drinking was abolished. These results indicate that preloading prevents the acquisition of schedule-induced drinking and abolishes established polydipsia.