1. The swimmeret system can be excited by perfusing the neuropeptide proctolin through the isolated ventral nerve cord of the crayfish. Previously silent preparations begin to generate a characteristic motor pattern, the swimmeret rhythm, in the nerves that innervate the swimmerets. The response to proctolin is dose dependent and reversible. The threshold concentration of proctolin perfused through the ventral artery is approximately 10(-8) M. The EC50 is 1.6 X 10(-6) M. 2. Proctolin-induced motor patterns have periods and phases similar to those of spontaneously generated motor patterns. The durations of the bursts of impulses in power-stroke motor neurons generated in the presence of proctolin are, however, significantly longer than those that occur during spontaneous activity. 3. DL-Octopamine inhibits the swimmeret system, both when the system is spontaneously active and when it has been excited by proctolin. The inhibition by octopamine is dose dependent and reversible. The threshold for inhibition is approximately 10(-6) M, and the EC50 is approximately 5 X 10(-5) M. 4. Octopamine's effect is mimicked by its agonists, synephrine and norepinephrine. Synephrine has a lower threshold concentration than does octopamine, but norepinephrine is much less effective than octopamine. 5. Octopamine's inhibition is partially blocked by an antagonist, phentolamine. 6. Phentolamine also blocks inhibition of the swimmeret system by inhibitory command interneurons. This block is dose dependent and can be partially overcome by stimulating the command interneurons at higher frequencies. 7. Perfusion with 11 other suspected crustacean neurotransmitters and transmitter analogues did not similarly excite or inhibit the swimmeret system, so we suggest that proctolin and octopamine are transmitters used by the neurons that normally control expression of the swimmeret rhythm.
Failure to provide effective analgesia to animals in noxious studies contravenes the obligation to refine animal experimentation and, by increasing 'noise' in physiological data sets, may decrease the scientific validity of results. Pig models of surgical conditions are becoming increasingly important and used for translational work. This review aimed to determine the extent to which the recent biomedical literature describes pain assessment and alleviation in pigs recovering from experimental surgery. Three databases (Medline, Web of Knowledge, and Google Scholar) were searched to find relevant studies published from January 2012 to March 2014. Information on pain assessment and peri- and postoperative analgesia was extracted. The review identified 233 papers meeting selection criteria. Most articles (193/233, 83%) described use of drugs with analgesic properties, but only 87/233 (37%) described postoperative analgesia. No article provided justification for the analgesic chosen, despite the lack of guidelines for analgesia in porcine surgical models and the lack of formal studies on this subject. Postoperative pain assessment was reported in only 23/233 (10%) articles. It was found that the reporting of postoperative pain management in the studies was remarkably low, reflecting either under-reporting or under-use. Analgesic description, when given, was frequently too limited to enable reproducibility. Development of a pain-scoring system in pigs, together with the mandatory description of pain management in submitted articles, would contribute to improved laboratory pig welfare.
Many rabbits show fear behaviours when lifted off the ground. Estimates from owner surveys suggest that around 60% of pet rabbits struggle when lifted and fear-related aggression is common. This article integrates information from both laboratory and pet rabbit studies to formulate a list of recommendations for appropriate handling of rabbits. Reduction of the frequency of the stressor can be achieved by educating owners on alternative management practices to reduce the need to carry their rabbits. However, in some situations, it is unavoidable that a rabbit is lifted. Amelioration of the stress in these instances can be achieved by a 2 pronged strategy. First, the population of rabbits can be made more resilient to infrequent stressors by selectively breeding for confident rabbits and by better socialisation of unweaned kits, and, where possible, training of individual animals to permit handling. Secondly, any unavoidable lifting can be made less stressful by educating veterinary staff in appropriate methods of holding rabbits during both consultations and inpatient care. Better understanding of appropriate interactions with rabbits will improve welfare.
The literature (2012-4) describing experimental pig surgery was reviewed to estimate the extent to which neuromuscular block (NMB) is used, to examine methods for ensuring unconsciousness, and to identify the rationale for use of NMB and establish the anaesthetist's training. In the first stage of a two-stage review, NMB use was estimated using Web of Knowledge to identify articles describing NMB during pig surgeries. In the second stage, PubMed and Google Scholar were used to increase the number of articles for determining measures taken to prevent accidental awareness during general anaesthesia (AAGA). The corresponding authors of screened articles were emailed four times to establish the reason for using NMB and the anaesthetists' backgrounds (medical, veterinary, or technical). The first search revealed NMB use in 80 of 411 (20%) studies. Of the 153 articles analysed in the second stage, two described strategies to reduce AAGA. Some (6%) papers did not provide information on anaesthetic doses; citations supporting anaesthetic efficacy were found in only 13. Five of 69 papers using inhalation agents measured end-tidal anaesthetic concentrations based on human, not porcine, minimal alveolar concentrations. The methods in 13% of articles reporting anaesthetic depth assessment were incomplete or questionable, or both; four described using somatic motor reflexes. Corresponding authors of 121 articles reported that the principal reason for NMB was improved 'surgical visualization' (26%). Medical or veterinary anaesthetists supervised anaesthesia in 70% of studies; non-anaesthetists provided NMB, unsupervised, in 23. Nine respondents prioritized experimental expediency over pig welfare. In laboratory pig studies, AAGA may be prevalent; reported details of its attempted prevention are woefully inadequate.
The neutering of pet rabbits has become more common in recent years due to recognition of the importance of species-specific social contact and the perceived risk of reproductive malignancies in unspayed older females. Here, GUEN BRADBURY: and GREG DICKENS: argue that the benefits of neutering singly housed rabbits (still the majority in the UK) may not outweigh the adverse effects of the procedure.
There are no guidelines for antimicrobial use in experimental animals even though appropriate selection is required to reduce risk of surgical site infection (SSI) and resistance development. Pigs are used extensively as experimental surgical models for people. This review compares reported antimicrobial prescription in recently published pig surgical studies (retrieved by PubMed, Web of Knowledge and Google Scholar) with human guidelines for prophylactic antimicrobial use (National Institute of Clinical Excellence and the American Society of Health-System Pharmacists). A five-point appropriate antimicrobial use index (AAUI), based on aforementioned guidelines, was used to grade 233 studies. Use of World Health Organization-designated critically important antimicrobials (CIA) was recorded. Antimicrobial use was described in 111 of 233 (48 per cent) papers. AAUI scores of 5 (maximal compliance) and 0 (no compliance) were awarded to 34 (15 per cent) and 101 (43 per cent) articles. Where reported, prophylactic antimicrobials were mostly administered after surgery (62/95, 65 per cent) and intramuscularly (36/72, 50 per cent). CIAs were described in 21 of 111 (19 per cent) papers and SSIs in 21 of 233 (9 per cent). Reported antimicrobial prophylaxis in experimental pig surgery deviates from human clinical guidelines. This has implications for antimicrobial resistance, study quality and animal welfare. Until species-specific guidelines are formulated, experimental surgical studies involving animals would probably benefit from adherence to human guidelines.
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