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At least 109 records · Page 6Linked to original sources
PubMed1985

Responses to conspecifics' urine by the degu (Octodon degus).

In nature the degu has been observed to deposit and to investigate scents. This study employed a captive group of these animals to investigate their responses to conspecific urinary marks in a neutral arena. Both sex classes served as subjects. They were presented with urine obtained from males, from females and a saline control. The females were found to be more active in responding. On the basis of sniffing frequency, they exhibited greater discriminative abilities than did the males. The urine from female donors was sniffed more frequently by all subjects. The frequency of approaching a mark and the time spent in the vicinity of a stimulus are interpreted as being investigatory responses. It seems that the marks deposited by females have a greater salience and that females are more sensitive to olfactory stimuli.

Animals↗
PubMed1989

New differences between the Wistar rat and Octodon degus, a putative laboratory animal resistant to morphine.

1. The effects of CNS depressants (methadone and alcohol) and natural neurotransmitters (NA and ACh) are studied in O. degus. 2. O. degus shows resistance to methadone in the formalin algesiometric test and EEG. 3. Ethanol elimination profile suggest the presence of an atypical alcohol dehydrogenase in O. degus 4. O. degus is extremely resistant to the pressor effects of noradrenaline 5. the isolated atrium of this rodent is 40 times more sensitive to the negative chronotropic effect of methadone, than the rat atrium. 6. These effects could be explained in terms of an important catecholamine and endorphin co-secretion from adrenal glands in O. degus.

Adrenal Glands↗
PubMed2001

Retinal projection to the dorsal raphe nucleus in the Chilean degus (Octodon degus).

A substantial projection from the retina to the dorsal raphe nucleus (DRN) has been demonstrated in the Chilean degus, a diurnal/crepuscular hystricomorph rodent. Following intraocular injection of cholera toxin subunit B (CTB), immunocytochemically labeled CTB-positive axons and terminals were observed in all major retinorecipient nuclei as well as in the DRN and periaqueductal gray (PAG) of the mesencephalon. Two streams of optic axons to the DRN were observed: one descending from the optic tract at the level of the pretectum and anterior superior colliculus, the other emerging as a small fascicle at the anterior pole of the inferior colliculus and descending bilaterally through the PAG. Contralateral retinal afferents in the DRN appeared to terminate primarily in the dorsomedial and lateral subdivisions of the DRN, and a less extensive ipsilateral component also was observed. Axonal arborizations were characterized by short branches and multiple varicosities, both in the DRN and in the PAG. The extent and density of DRN retinal afferents were not as extensive as previously observed in Mongolian gerbils using identical techniques, but the retinal-DRN projection is considerably larger in degus than in rats. The functional significance of the retinal-DRN pathway remains to be determined, although a variety of evidence indicates that light may directly affect the activity of neurons and serotonin levels in the DRN.

Animals↗
PubMed1999

Photic responses of suprachiasmatic area neurons in diurnal degus (Octodon degus) and nocturnal rats (Rattus norvegicus).

Photic sensitivity of cells in the suprachiasmatic nuclei (SCN), the principal pacemaker of the mammalian circadian system, has been documented in several species. In nocturnal rodents, the majority of photically responsive SCN cells are activated by retinal illumination. One report identified mostly photic suppressions among SCN cells in a diurnal rodent, studied under somewhat different conditions. We examined photic sensitivity of SCN cells in a predominantly diurnal rodent, the degu, studied in vivo under identical conditions to rats, and found that a large majority of photic SCN cells were suppressed by light. In both rats and degus, SCN cells were more responsive to light during the subjective night than during the subjective day. Light-responsive cells did not show a daily rhythm in baseline firing rates in either species, but rat SCN cells that did not respond to light were more active spontaneously during the subjective day. Light-unresponsive SCN cells in degus did not show a similar pattern. There are substantial differences in the neurophysiological activity and photic responsiveness of SCN cells in diurnal degus and nocturnal rats.

Animals↗
PubMedDate not supplied

The ultrastructure of the trophoblastic layer of the degu (Octodon degus) placenta: a re-evaluation of the 'channel problem'.

Previous studies on immersion-fixed specimens of the haemomonochorial labyrinthine chorioallantoic placenta of the degu have made visible channels or pores which completely crossed the trophoblastic layer; for the first time hints for an open connection between maternal blood spaces and fetal interstitium were demonstrated in a placenta. This important finding was re-evaluated by means of transmission electron microscopy paying particular attention to the influence of the mode of fixation and of ischaemic periods prior to fixation. Thirty placentae from seven near-term degu (estimated gestational age 80-90 days) were fixed at various times (5-45 min) after maternal death. Placentae were perfused in situ via the aorta/uterine arteries or the umbilical vein with 2.2 per cent phosphate-buffered glutaraldehyde (n = 7, ischaemic periods < 5-45 min) or lanthanum hydroxide/osmium tetroxide (n = 7, ischaemic periods < 5 min), or were immersion-fixed in 2.2 per cent phosphate-buffered glutaraldehyde (n = 16, ischaemic periods 10-45 min). In material with brief ischaemic periods (n = 3, 5-10 min) no open connections between the maternal blood lacunae and fetal interstitium could be detected. Instead, occasional foci of trophoblast reduced to a thickness of 0.1 micron were found. After ischaemic periods exceeding 10 min, the thin trophoblastic diaphragms had partly disappeared resulting in complete transtrophoblastic pores. It is likely, therefore, that visible trophoblastic pores or channels in the degu placenta are ischaemic artefacts. Application of lanthanum hydroxide from the fetal circulation showed that a branching system of membrane-lined tubules (15-50 nm wide) intruded the trophoblast from its basal side, as has been reported for the guinea-pig and human placenta. It remains to be investigated whether these invaginations belong to a continuous transtrophoblastic channel system.

Animals↗
PubMed1986

Responses to salivary olfactants in relation to dominance of the degu (Octodon degus).

Large amounts of head sniffing and grooming have been associated with social dominance in the degu. This study examined whether salivary olfactants act as cues which could potentially mediate social dominance in 4 male and 8 female adults. Using salivary samples taken from the buccal cavities of partners of predetermined status, no preferences for dominant or submissive stimuli were evident. Comparison of work with the degu and that with other species was made.

Animals↗
PubMed1980

Anatomy of reproductive tract in Octodon degus Molina: a nonscrotal rodent.

O. degus reproductive tract is characterized externally by a perianal circle with the penis pointing posteriorly. Beneath the perianal circle is the cremasteric sac. Testes are always inside the abdomen, with the epididymis attached to them but the cauda epididymis lays inside the cremasteric sac. Vas deferens and seminal vesicles open independently into the urethra. Three pairs of lateral prostatic lobes open by many ducts into the urethra. The corpora spongiosa holds the urethra in the ventral groove of the corpus cavernosum. The corpus cavernosa are inserted into the bulbo cavernosum muscle and at its distal end are attached to the base of the baculum, that lay under the dorsal face of the glans. The glans has two openings: the urinary meatus and the intromittent sac. The characteristics of the testicular artery agree with the anatomy expected for animals with intrabdominal testes; it is relatively short, with few loops and a wide diameter. Many of these anatomical features are shared by other caviomorphal rodents. If testicular temperature is similar to body temperature in these animals as in O. degus (36.0 degrees and 37.2 degrees C respectively), they would exhibit little testicular thermal sensibility. Among these rodents O. degus has the lowest body temperature. Moreover this work reinforces the hypothesis that descent of the testis into the scrotum has occurred secondarily to the immigration of the cauda epididymis.

Animals↗
PubMed1975

Preparation of rhinovirus antisera in the South American hystricomorph rodent, Octodon degus (38507).

Rhinovirus antisera have been prepared for rhinoviruses (RV) 7,9,26,32,67 and 87 in guinea pigs and in degus. Titers achieved were either similar in the 2 animals (RV7) somewhat higher in the degu (RV9 and RV32) or clearly higher in the degu (RV26, RV67 and RV87). Specificity of the antisera was similar in both animals. In special instances where it is difficult to prepare high-titered rhinovirus antisera in the guinea pig, the degu offers an attractive alternative source.

Animals↗