Casomorphins reduce separation distress in chicks

Intraventricular administration of various chain length casomorphins (CM) reliably reduced separation induced distress vocalizations (DVs) in young domestic chicks. At a dose of 50 nanomoles, CM-5 was more potent than either CM-4 or CM-7, but for each the duration of action was approximately half an hour, with CM-7 having a somewhat longer effect. This suppression of DVs was partially antagonized by naloxone (1 mg/kg).     

Effects of beta-chlornaltrexamine on food intake, body weight and opioid-induced feeding

beta-Chlornaltrexamine (beta-CNA) is a non-equilibrium opioid receptor antagonist which alkylates and inactivates opioid receptors. Because opioid peptides are thought to contribute to the regulation of food intake, we examined the effects of intracerebroventricular (icv) injections of beta-CNA on the food intake and body weight of male rats. We also tested the ability of beta-CNA to block food intake stimulated by selective agonists of kappa, mu and delta opioid receptors: dynorphin A2 (DYN), Tyr-D-Ala-Gly-(Me)Phe-Gly-ol (DAGO), and [(D-Ser2,Leu5]-enkephalin-Thr6 (DSLET). Treatment with beta-CNA caused a long-term (2-4 days) reduction in daily food intake and a concomitant reduction in body weight. An additional experiment indicated that the weight loss after beta-CNA treatment could be completely accounted for by the reduction in intake. beta-CNA treatment also abolished or greatly attenuated the feeding effects of DAGO, DSLET and DYN, even when these peptides were tested 26 hours after beta-CNA administration. The long duration of the effects of beta-CNA suggests that this compound will be a useful pharmacological tool in further study of the opioid feeding system.     

Modulation of separation distress by alpha-MSH

The effects of centrally administered alpha-MSH on separation-induced distress vocalizations (DVs) and squatting were evaluated in domestic chicks for dose-response, time course, and interactions with peripheral naloxone and both peripheral and central morphine. Some of the tests were conducted in both the presence and absence of social stimuli (mirrors or a conspecific). Doses of 0.04 microgram of alpha-MSH or greater eliminated the usual suppression of DVs produced by mirrors or conspecifics. This effect lasted 10-15 minutes and was followed by inhibition of DVs, accompanied by a dose-dependent vigilant squatting posture, that lasted about one hour. These effects showed no development of tolerance to repeated alpha-MSH injections over a six-day period, and no apparent interaction with the effects of peripherally injected naloxone or either peripherally or centrally injected morphine. It is suggested that, in keeping with its role in defensive camouflage in amphibians, alpha-MSH in chicks may activate a central state akin to fear to adaptively modulate DVs and defensive hiding.     

Effects of separation and novelty on distress vocalizations and cortisol in the common marmoset (Callithrix jacchus)

In socially-bonding species, separation from familiar attachment figures is widely known to stimulate a physiological and behavioral stress response. This study investigated the hormonal and vocal responses of adult common marmosets to separation from familiar group members and to 24 hr of cohabitation with an unfamiliar opposite-sex conspecific. All subjects were removed from their home cages and placed into a novel environment for 20 min. In one group, marmosets were exposed to an unfamiliar, opposite-sex partner in the novel environment and remained paired with this partner for the 24 hr test period. In three other groups, marmosets experienced the novel environment alone and subsequently were returned to their original social- or single-housing condition, or kept separate from their social groups for a 24 h period. Blood samples were collected the day before, and at 30 min, 90 min, and at 24 h after separation. Cortisol responses were differentially affected by the length of separation and the presence of unfamiliar conspecifics. Brief separation followed by the return to the social group had minimal effect on plasma cortisol levels. All marmosets produced high levels of separation calls in the novel environment, but there was no apparent relationship between calling and cortisol levels. The lack of a temporal relationship between the production of distress vocalizations and serum cortisol has previously been noted in squirrel monkey and rhesus monkey infant separation studies; the behavioral and physiological responses to separation appear to be similarly dissociated in the marmoset. Further, the characteristics of a separation environment can differentially affect the hormonal response by adult marmosets without differentially affecting their behavioral response.     

Effects of ACTH(1-24) and ACTH/MSH(4-10) on isolation-induced distress vocalization in domestic chicks

The effects of centrally administered ACTH(1-24) and ACTH(4-10) on isolation-induced distress vocalizations (DVs) were assessed in the presence or absence of social cues (mirrored and plain environments). A dose-response analysis indicated that ACTH(1-24) at doses of 0.5 nM and above increased DVs relative to controls when the animals were tested in mirrored or social environments which reduce baseline levels of calling. This effect, however, was short-lived (approx. 15 min). When tested again 1 hr after injection, the treated animals did not differ from controls. ACTH/MSH(4-10) had no effect on vocalization when the animals were tested immediately after injection, but marginally increased calling when animals were tested an hour later. In addition to vocalization changes, ACTH(1-24) induced squatting when animals were isolated in the test boxes, and yawning, head shaking, wing flapping and preening when animals were reunited after testing. ACTH(1-24)-treated chicks also exhibited longer latencies to close their eyes when they were held in the cupped hands of the experimenter. Taken together, the results suggest that ACTH(1-24) induces a central state of arousal in chicks that resembles fear/anxiety.     

Effects of begging on growth rates of nestling chicks

We investigated whether an increase in begging levels delaysgrowth of chicks. In experiment 1, we hand-reared nine pairsof ring dove squabs, divided into a control and a begging group.All squabs received similar amounts of food, but those in thebegging group had to beg for a prolonged period in order tobe fed, while squabs in the control group received food withoutbegging. Squabs stopped responding to the treatment after 10days and, at that time, there was no effect of induced beggingon their body mass. In experiment 2, we hand-reared 27 pairsof magpie chicks for 3 days. The design of experiment 2 wassimilar to that of experiment 1. Daily food intake and beggingaffected growth rates. On average, chicks in the begging groupgrew 0.8 g/day less than control chicks, which represents adecrease of 8.15% in growth rate. Because growth is usuallypositively associated with expected fitness, this demonstratesthat begging is a costly behavior, an assumption routinelymade in models of begging behavior.     

Effects of antihelminthic treatment on cell-mediated immunity in Gentoo penguin chicks

Intestinal parasites suppose a cost to hosts as they compete directly for nutritional resources. Therefore, hosts must defend themselves against intestinal parasites by mounting an immune response. Many penguin species acquire parasites through their diet and transfer these parasites to their chicks when feeding them. High parasite loads in penguin chicks could have effects on their growth and body condition, and ultimately on their survival. Here, we evaluated the effect of parasites on the cell-mediated immune system in Gentoo penguin (Pygoscelis papua) chicks at Stranger Point (25 de Mayo/King George Island, South Shetland Islands). To this end, 12 chicks were experimentally deparasitized with a mixture of anthelminthic drugs (albendazole and praziquantel), whereas 10 others were kept as control. We measured cutaneous cell-mediated immunity in response to immunization with phytohemagglutinin (PHA). We also analyzed the leukocyte profile in both treated and control groups before and after the treatment. After the treatment, deparasitized birds showed larger foot-web swelling in response to PHA injection than control birds. Deparasitized penguins also showed lower eosinophil and monocyte counts than controls, whereas heterophils, lymphocytes, and total white blood cell counts did not differ between groups. Our results suggest that Gentoo penguin chicks parasitized with intestinal parasites suffer a cost in terms of reduced cell-mediated immune responses that could ultimately affect their survival.     

Effects of orally administrated amino acids on myofibrillar proteolysis in chicks

We examined the effects of orally administrated amino acids on myfibrillar proteolysis in food-deprived chicks. Plasma N(tau)-methylhistidine concentration, as an index of myofibrillar proteolysis, was decreased by the administration of Glu, Gly, Ala, Leu, Ile, Ser, Thr, Met, Trp, Asn, Gln, Pro, Lys and Arg but not by Asp, Val, Phe, Tyr or His to chicks. Orally administrated Cys was fatal to chicks. These results indicate that oral Glu, Gly, Ala, Leu, Ile, Ser, Thr, Met, Trp, Asn, Gln, Pro, Lys and Arg administration suppressed myofibrillar proteolysis in chicks.     

Effects of social influence on neonatal approach responses of Gallus chicks

Although most laboratory studies of imprinting rear and test subjects individually, in the natural setting birds are imprinted in groups. In order to approximate and evaluate naturally occuring conditions, the present study compared the approach responses of chicks reared and trained alone to those reared and trained in pairs to an audio-visual imprinting stimulus. The responses of both groups were virtually identical during the presence of the imprinting stimulus. However, under conditions of experimental extinction, the paired trained birds (now tested alone) were more resistant to extinction than their isolated counterparts, thus suggesting that birds with prior social experience are more strongly imprinted than has been previously reported.     

Effects of zinc supplementation to ration on some hematological parameters in broiler chicks

The aim of the study was to examine the effects of zinc supplementation on some hematological parameters. Sixty newborn male broiler chicks were utilized in the study. Zinc (Zn) was added into drinking water at levels of 0, 125, 500, and 1000 mg/kg. In the study, there was no significant difference between control and Zn-supplemented groups in erythrocyte count, hemoglobin amount, hematocrit levels, total leukocyte count, and differential leukocyte % levels, but the α-naphthyl acetate esterase ANAE(+) lymphocyte rate significantly (p<0.05) increased in the 125-ppm Zn-supplemented group compared with the control group. In conclusion, the data obtained may be beneficial in demonstrating the effects of zinc on, at least, these parameters.     

Effects of anisomycin on brain protein synthesis and passive avoidance learning in newborn chicks

The effects of anisomycin (ANM) on newborn chicks have been studied with respect to brain protein synthesis, growth, EEG, toxicity, and several passive avoidance learning tasks. It was found that intracerebral ANM (80 nmol) gave a maximum inhibition of brain protein synthesis of 30%, while a combination of subcutaneous (10 μmol; 53 mg/kg) plus intracerebral (80 nmol; 21 μg) ANM, inhibited by 91% in the first 2 hr and by 75% in the subsequent 2 hr period. Cycloheximide (CXM) also in combined injections at the same doses as ANM, inhibited by 97% in the 4 hr that followed injection. However, all the CXM-injected chicks were dead by 18 hr, while the lethality of ANM did not differ from that of saline. ANM also did not affect EEG measured at 1, 3, 5, or 24 hr following the subcutaneous plus intracerebral injections, nor did ANM affect body or brain growth curves or brain protein accretion. In the learning experiments, animals were initially trained to peck at water-coated metal spheres (type A learning) or at water-imbibed birdseed (types B and C learning) in less than 1 sec, and were exposed to the same lures treated with the aversant methylanthranilate (MeA) one day later on one occasion (types A and B learning) or exposed twice (type C learning) and tested for learning retention one day later. Learning criterion was set as failure to peck at the lure during the first 20 sec of presentation. If ANM was injected 1 hr prior to MeA exposure, large and highly significant memory deficits were found during the retention test, as compared with saline injected controls. No effect of ANM was seen, however, if it was injected one day after learning, indicating that it did not interfere with retrieval mechanisms. ANM also decreased the external manifestations of fear or displeasure that chicks express during retention testing. Such manifestations have a high correlation with pecking suppression (r = 0.88, P < 0.001).