L F Mikkelsen

Publications (3)13.26 Total impact

• Article: The effect of environmental enrichment on the behavior of captive tufted capuchin monkeys (Cebus apella).

  Kirsten R Jacobsen, L F Mikkelsen, J Hau
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  ABSTRACT: The authors provided different forms of environmental enrichment to six old laboratory male tufted capuchin monkeys (Cebus apella) and studied the behavior of the monkeys during a baseline period and during three enrichment periods. Each observation period lasted 5 d, with an interval of 6 d between periods. During the first enrichment period, the authors provided Buster cubes and wood cylinders with drilled holes filled with gum arabic. During the second enrichment period, monkeys were provided with a deep litter of bark shavings, and during the third enrichment period, they were given Buster cubes, wood cylinders and bark shavings. When provided with enrichment, the monkeys engaged in natural, species-specific activities and began to exhibit behavioral profiles that more closely resembled those of their natural counterparts. This suggests that their psychological well-being had improved and that group housing combined with environmental enrichment can improve the welfare of old laboratory tufted capuchin monkeys that were previously housed individually.
  Lab Animal 09/2010; 39(9):269-77. · 0.38 Impact Factor
• Article: Quality of plasma sampled by different methods for multiple blood sampling in mice.

  S D Christensen, L F Mikkelsen, J J Fels, T B Bodvarsdóttir, A K Hansen
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  ABSTRACT: For oral glucose tolerance test (OGTT) in mice, multiple blood samples need to be taken within a few hours from conscious mice. Today, a number of essential parameters may be analysed on very small amounts of plasma, thus reducing the number of animals to be used. It is, however, crucial to obtain high-quality plasma or serum in order to avoid increased data variation and thereby increased group sizes. The aim of this study was to find the most valid and reproducible method for withdrawal of blood samples when performing OGTT. Four methods, i.e. amputation of the tail tip, lateral tail incision, puncture of the tail tip and periorbital puncture, were selected for testing at 21 degrees C and 30 degrees C after a pilot study. For each method, four blood samples were drawn from C57BL/6 mice at 30 min intervals. The presence of clots was registered, haemolysis was monitored spectrophotometrically at 430 nm, and it was noted whether it was possible to achieve 30-50 microL blood. Furthermore, a small amount of extra blood was sampled before and after the four samplings for testing of whether the sampling induced a blood glucose change over the 90 min test period. All methods resulted in acceptable amounts of plasma. Clots were observed in a sparse number of samples with no significant differences between the methods. Periorbital puncture did not lead to any haemolysed samples at all, and lateral tail incision resulted in only a few haemolysed samples, while puncture or amputation of the tail tip induced haemolysis in a significant number of samples. All methods, except for puncture of the tail tip, influenced blood glucose. Periorbital puncture resulted in a dramatic increase in blood glucose of up to 3.5 mmol/L indicating that it is stressful. Although lateral tail incision also had some impact on blood glucose, it seems to be the method of choice for OGTT, as it is likely to produce a clot-free non-haemolysed sample, while periorbital sampling, although producing a high quality of sample, induces such a dramatic change in blood glucose that it should not be applied for OGTT in mice.
  Laboratory Animals 12/2008; 43(1):65-71. · 1.21 Impact Factor
• Article: The effect of intrathecal opioid-receptor agonists on visceral noxious stimulation in rabbits.

  F M Borgbjerg, C Frigast, J B Madsen, L F Mikkelsen
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  ABSTRACT: Conflicting results have been published concerning the effects of different opioid-receptor agonists against visceral noxious stimulation. The introduction of colorectal distention facilitates research in this field. The aim of this study was to examine intrathecally administered opioid agonists against colorectal distention in conscious rabbits. Rabbits were equipped with a subcutaneous intrathecal injection system. Colorectal distention was induced by inflation of a balloon inserted into the descending colon. The test parameter was the pressure eliciting a characteristic visceromotor response. Examinations were performed before and after administration of the following drugs: morphine, U50488H, [D-Pen2, D-Pen5]enkephalin (DPDPE), naloxone, MR2266, naltrindole, saline, and acidified saline. The visceromotor response to colorectal distention was inhibited in a dose-dependent fashion by intrathecal opioids acting as agonists at all three types of opioid receptors. Morphine was antagonized more effectively by intrathecal than intramuscular naloxone. U50488H and DPDPE were equally antagonized by the specific antagonists MR2266 and naltrindole. Electrical thresholds in the lumbar region were increased, although they remained unaltered in the cervical region after administration of all three agonists. Intrathecal administration of different opioid agonists produces a dose-dependent spinal effect. The rank order of potencies in this model is DPDPE > U50488H > morphine > saline = 0.
  Gastroenterology 01/1996; 110(1):139-46. · 11.68 Impact Factor