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Tyrosine hydroxylase-immunoreactive neurons in the nucleus basalis of the common marmoset (Callithrix jacchus).

In the course of characterizing the distribution of putative catecholaminergic neurons in the brain of the common marmoset, we encountered a population of such cells in the basal forebrain. Tyrosine hydroxylase-immunoreactive neurons are abundant within the nucleus basalis magnocellularis throughout its entire rostrocaudal extent, but not in other cholinergic basal forebrain nuclei. Most tyrosine hydroxylase-immunoreactive cells are large and multipolar. Double staining with antibodies to choline acetyltransferase or nerve growth factor receptor confirmed that these tyrosine hydroxylase-immunoreactive neurons are cholinergic, and compose at least 40% of the nucleus basalis cholinergic cells. The presence of a catecholamine-synthesizing enzyme in the neurons that provide the major cholinergic input to the neocortex may have important consequences for cortical function, and may be relevant to the vulnerability of the nucleus basalis in certain neurodegenerative disorders.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine

Correlations among measures of playfulness and skillfulness in captive common marmosets (Callithrix jacchus jacchus).

Infant sensorimotor and social skills, playfulness, and nonplayful behaviors were measured in common marmosets from 6 to 22 weeks old. Different measures of skill showed a low concordance, implying that skill is a multiple rather than unitary attribute. Significant correlations were found between the amount of social play infants performed from 11 to 13 weeks of age and their performance at 14 weeks in (1) competitive food tests with their mothers, and in (2) their ability to negotiate an obstacle for a food reward. Significant correlations were also found between these skills and nonplayful behaviors, however. Comparable analyses at other ages revealed few significant correlations, suggesting that the association between social play and skills is restricted to the age when infants are rapidly becoming independent of their caregivers both for locomotion and food. Age-specific correlations occurred between changes in levels of skills and both playful and nonplay behaviors. Our results are consistent with the hypothesis that social play promotes the development of skills, but alternative explanations are possible.

Animals

Effects on the behavior of infant common marmosets (Callithrix jacchus) of separation from caregivers and of drug-induced reduction in caregiver responsiveness.

The effects of separating 4-week-old twin marmosets for 8 days from their families are compared with the effects of leaving 4-week-old infants with their families, but reducing the responsiveness of their caregivers for 8 days by administration of the tranquilizer fluphenazine decanoate. Both treatments reduce infant mobility, abolish play, and increase the time that infants spend with each other. During the period after the termination of the treatment, both treatment groups continue to play and move less than controls, and try to climb onto the mothers more frequently. These results are consistent with the hypothesis that the principal factor precipitating disturbed behaviors in infant monkeys subjected to long-term separation is disruption of the infant-caregiver relationship rather than the separation itself. Some post-treatment differences occur between separated and tranquilized groups. Notably, reunion after separation appears to involve a marked readjustment of the behavior of all family members to the return of the infants, whereas withdrawal of the tranquilizer does not.

Animals

The diagnostic usefulness of isocitrate dehydrogenase (ICDH) in the marmoset (Callithrix jacchus).

Marmosets were given either a hepatotoxin, carbon tetrachloride, orally or an i.m. injection of a mytoxin, chlorpromazine. Although muscle damage alone caused small increases in the plasma levels of lactate dehydrogenase, alanine aminotransferase, aspartate aminotransferase and isocitrate dehydrogenase (ICDH), only the isoenzyme analysis of ICDH can differentiate definitely between liver and muscle damage. Only very severe muscle damage can increase the plasma concentration of this enzyme but, in this case, the elevation of plasma creatinine kinase levels helps differentiation. It is recommended that the elevation of ICDH is the most specific indicator of hepatic damage in the marmoset.

Alanine Transaminase

Intercellular communication between cultured granulosa cells of the marmoset (Callithrix jacchus).

The influence of follicle-stimulating hormone, forskolin, insulin-like growth factor type I, epidermal growth factor, and 12-tetradecanoyl-phorbol-13-acetate on marmoset granulosa cell communication via gap junctions was investigated by morphological means and microinjection of carboxyfluorescein. Gap junctions between neighbouring granulosa cells were present in all groups. The number, but not length, of gap junctions between marmoset granulosa cells increased when the cells had been treated with follicle-stimulating hormone, insulin-like growth factor type I, and follicle-stimulating hormone plus insulin-like growth factor type I. No effect on gap junctions was seen, after exposure of the cells to the other three substances. Carboxyfluorescein and counting of the surrounding labelled cells showed that supplementation with follicle-stimulating hormone, forskolin, insulin-like growth factor type I and epidermal growth factor from the beginning of cultivation led to an increase in stained cells after 48 h. When treatment was started in 48 h cultures the substances reached their maximal activity within 30 min (forskolin and epidermal growth factor) or 3 h (follicle-stimulating hormone and insulin-like growth factor type I). Spreading of the fluorescent dye was inhibited when the medium was supplemented with 12-tetradecanoyl-phorbol-13-acetate. This effect was maximal after 30 min. Additive effects regarding the coupling of the cells were seen by combining of epidermal growth factor with follicle-stimulating hormone, but not with insulin-like growth factor type I or forskolin plus follicle-stimulating hormone.

Animals

A conveyor belt task for assessing visuo-motor coordination in the marmoset (Callithrix jacchus): effects of diazepam, chlorpromazine, pentobarbital and d-amphetamine.

A conveyor belt task for assessing visuo-motor coordination in the marmoset is described. Animals are motivated by apple, a preferred food, under a state of minimal food deprivation. The apparatus used was designed to test animals within their home cages and not restrained in any way, thus avoiding possible confounding factors associated with restraint stress. Stable baseline levels of performance were reached by all animals in a median of 24 sessions. Performance was shown to be differentially sensitive to the effects of four psychoactive drugs. Moderate doses of diazepam, chlorpromazine and pentobarbital disrupted visuo-motor coordination in a dose-related manner. The possibility that disruption of performance observed at higher doses may have resulted from non-specific actions of these drugs such as decreases in feeding motivation were not supported by results from ancillary experiments. Changes in performance characteristic of high dose effects were similar in nature to changes observed when the degree of task difficulty was increased. Doses of d-amphetamine up to and including those reported to produce signs of stereotypy failed to influence performance. The potential of the conveyor belt task for measuring visuo-motor coordination in both primate and rodent species is discussed.

Animals

Investigations into the induction of chronic experimental arthritis in the common marmoset (Callithrix jacchus).

In an attempt to produce a superior model of rheumatoid arthritis, experiments have been performed to investigate the ease of induction of experimental arthritis in marmosets by immunological means. Marmosets were sensitised with the following combinations of antigen and adjuvant: ovalbumin in Freund's complete adjuvant (FCA), ovalbumin in FCA + Bordetella pertussis, methylated-BSA in FCA + B. pertussis or human fibrin in FCA + B. pertussis, and subsequently injected with the corresponding antigen in saline into one knee joint. Animals receiving ovalbumin, with or without B. pertussis, produced only a weak transient monoarticular synovitis. Animals receiving Met-BSA + B. pertussis produced a chronic synovitis but only mild erosive changes were apparent even 21 weeks after intraarticular injection. Animals receiving human fibrin produced a transient monoarticular synovitis of moderate intensity. These results indicate that the marmoset offers no obvious advantages over the rabbit for the induction of experimental rheumatoid arthritis.

Animals

Anteromedial hypothalamic lesions block proceptivity but not receptivity in the female common marmoset (Callithrix jacchus).

The sexual behavior of 8, estradiol-treated, ovariectomized common marmosets was recorded prior to and after bilateral radiofrequency lesions of the hypothalamus. Lesions of the anterior hypothalamus, which extended to varying degrees into the medial hypothalamus, virtually abolished proceptive tongue-flicking and staring displays. Tongue-flicking during copulation also decreased, but the females did not show any significant increase in the number of mounts which they refused or terminated with the exception of one animal which had received more extensive damage to the medial hypothalamus. Significant increases in the frequencies of allogrooming and grooming invitations also occurred after the females had been lesioned. Sexual behavior was not significantly altered in 3 females which received sham lesions. These results provide the first direct evidence for a neuroanatomical distinction between hypothalamic mechanisms which regulate proceptivity and receptivity in primates.

Animals

A new heterotopic callosal projection of primary visual cortex in the monkey, Callithrix jacchus.

A callosal projection of area 17 upon the dorsomedial visual area in the marmoset monkey was demonstrated by means of retrograde transport of neuronal tracers. The projection was restricted to those regions representing the vertical meridian in the two areas. This finding, and the data of other authors, indicate that the monkey area 17 projects transcallosally onto homotopic and several heterotopic targets.

Animals

Behavioural consequences of the infusion of dopamine into the nucleus accumbens of the common marmoset (Callithrix jacchus).

Marmosets, shown to have comparable levels of spontaneous locomotor activity, assessed in cages equipped with infra-red photocell units, could be separated into "high", "moderate" and "low activity" responders on the basis of their locomotor hyperactivity response to peripherally administered (-)N-n-propylnorapomorphine [(-)NPA]. Animals selected as "low" and "high activity" responders to (-)NPA were subjected to chronic infusion of dopamine, or its solvent, bilaterally into the nucleus accumbens for 13 days through Alzet osmotic minipumps. Both "low" and "high activity" responders exhibited an increased locomotor activity which peaked on days 6-7 of the infusion. This hyperactivity, caused by infusion of dopamine was antagonised by small doses of sulpiride and fluphenazine. After the infusion, the level of spontaneous locomotor activity of the marmosets was unchanged from pre-infusion values. However, 2-3 weeks after discontinuing the infusion, the animals initially classified as "low activity" responders showed markedly enhanced activity when challenged with (-)NPA, and conversely, animals initially classified as "high activity" responders showed a reduced responsiveness to (-)NPA. It is concluded that the consequences of a persistent increase in the activity of dopamine in the nucleus accumbens of the brain of the marmoset are to (a) enhance locomotor activity during infusion and (b) after discontinuing infusion, to modify the locomotor responsiveness to challenge with a dopamine agonist, with the direction of the change dependent on the initial basal locomotor responsiveness to (-)NPA.

Animals

The effect of the ovarian cycle on the sexual behaviour of the common marmoset (Callithrix jacchus).

The sexual behaviour of 7 pairs of marmosets was observed during 30 minute tests for 44-68 days and blood samples were collected from females for measurement of plasma progesterone, testosterone and oestrone. Copulations occurred throughout the ovarian cycle of 24-30 days. Females used a "tongue-flicking" display both as an invitational behaviour (proceptive tongue-flicks) and during copulation (receptive tongue-flicks) most frequently during the peri-ovulatory period. Frequencies of proceptivity were correlated positively with high mean levels of testosterone and oestrone during the cycle and with a short follicular phase. Males showed significant increases in tongue-flicks, mounts and ejaculations during the peri-ovulatory phase, together with a shortened post-ejaculatory interval and increased duration of penile erection after ejaculation. A retrospective analysis showed that these changes in the males' behaviour occurred only during tests where females were proceptive and not during other tests in the peri-ovulatory period. Females refused significantly more of the males' mounting attempts during the luteal phase and a corresponding reduction in mount frequency occurred at this time. Grooming, scent-marking, olfactory inspections and some other behaviours did not alter significantly in either sex during the ovarian cycle.

Animals

Effects of oestradiol 17B, progesterone and testosterone upon proceptivity and receptivity in ovariectomized common marmosets (Callithrix jacchus).

The sexual behaviour of eight pairs of marmosets was observed during blocks of 30 minute tests after the ovariectomized female partners were treated with physiological doses of testosterone, oestradiol and progesterone. The effects of an intra-vaginal progesterone treatment were also investigated. Pre-ovulatory levels of oestradiol significantly increased the females' proceptive and receptive tongue-flicking displays and reduced the percentage of mounts refused. Mid-luteal levels of progesterone, by comparison, virtually abolished proceptive and receptive tongue-flicking and significantly increased mount refusals. Testosterone treatment was without effect. Vaginal application of progesterone unlike subcutaneous implantation of the hormone did not significantly alter the females' sexual behaviour. These results indicate that central actions of oestradiol and progesterone upon proceptivity and receptivity may occur in this primate, although further research using intra-cranial implants of these steroids is required to test this hypothesis.

Animals

Genital sensory feedback and sexual behaviour in male and female marmosets (Callithrix jacchus).

Local anaesthesia (using lidocaine) of the penis, or of the vagina and cervix caused marked changes in the sexual behaviour of marmosets. Penile desensitization did not affect sexual arousal or erectile capacity. However, intromission latencies increased and 7 out of 10 males failed to intromit during some post-lidocaine tests. Females failed to show several behavioural patterns which normally occur during intromission (shrugging body movements, head turning and opening the mouth) or exhibited them at reduced frequencies after intra-vaginal application of lidocaine. The tendency of females to terminate mounts after ejaculation had occurred was also reduced with resultant increases in intromission duration in all cases. Desensitization of the females' external genitalia had no effect upon sexual behaviour. Co-ordination of copulatory behaviour in this primate species depends, in part, upon afferent stimuli from the penis and from the vagina or cervix.

Animals

Post-partum changes in hormones and sexual behaviour in captive groups of marmosets (Callithrix jacchus).

Video-tape recordings were made of behavioural interactions in eight family groups of marmosets for 24-30 days after parturition. Blood samples were collected from females for measurement of plasma luteinizing hormone (LH) and progesterone. A pre-ovulatory LH surge occurred in six females between days 10-18 (mean +/- sem, 13.8 +/- 1.3 days). In these groups, sexual interactions increased in frequency during the post-partum period and males began to initiate mounts on days 1, 2, 2, 6, 8 and 10 respectively. Mount and ejaculation frequencies increased significantly during the peri-ovulatory phase as compared to the pre-ovulatory phase and females were more proceptive and receptive than in the early post-partum period. Peri-ovulatory increases in sexual activity were more pronounced in 3 groups in which females had failed to conceive. In the remaining 3 groups, sexual interactions tended to continue at higher levels into the post-ovulatory phase when the females were pregnant. In captive marmoset groups, copulatory behaviour during the post-partum period is stimulated by changes in non-behavioural cues from the female (increased sexual attractiveness to the male) as well as by changes in her behaviour (proceptivity, receptivity) which vary in importance between individuals.

Aggression

Effects of adrenalectomy upon proceptivity, receptivity and sexual attractiveness in ovariectomized marmosets (Callithrix jacchus).

The sexual behaviour of seven pairs of marmosets was observed during blocks of 30 minute tests before and after the ovariectomized partners were bilaterally adrenalectomized. Adrenalectomized females were maintained by intramuscular injections of deoxycorticosterone pivalate (DC) and hydrocortisone hemisuccinate (HC). Twice daily injections of HC were required to maintain the high levels of plasma cortisol typical of marmosets and some other New World primates. Adrenalectomy had no significant effects upon proceptivity, receptivity or female sexual attractiveness. Increasing the replacement dose of DC had no effects upon sexual behaviour. Oestradiol treatment caused a marked increase in proceptivity (tongue-flicking, staring and immobile displays) and in receptive tongue-flicking behaviour. Males ejaculated more frequently during tests with oestradiol-treated partners. These results indicate that during "pair tests" adrenocortical sex steroids are not essential for maintenance of sexual behaviour in female marmosets and that activation of proceptivity by oestradiol 17 beta can occur in the absence of the adrenal glands.

Adrenalectomy

Penile spines affect copulatory behaviour in a primate (Callithrix jacchus).

Androgen-dependent, keratinized "spines" occur on the glans penis in many rodents, primates and other mammals. Since penile spines overlie dermal tactile receptors, they may play a role in copulatory behaviour. An experiment was conducted to test this hypothesis. Sixteen sexually experienced adult male marmosets were paired with ovariectomized females before, and after, removal of penile spines (using thioglycollate cream applied to the glans under anaesthesia) or a sham operation. Spine removal resulted in an increased duration of preintromission pelvic thrusting (mean +/- s.e.m. from 6.87 +/- 1.09 to 14.94 +/- 3.32 s, p = 0.05) and of intromitted thrusting (from 1.73 +/- 0.11 to 2.0 +/- 0.11 s, p less than 0.05). Three males exhibited partial intromissions during some postspinectomy tests, an effect which had not been observed prior to the operation. Sham operations had no behavioural effects. Results indicate that penile spines play a significant (but not indispensible) role in sensory feedback during copulation in this primate species.

Androgens