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. Author manuscript; available in PMC: 2015 Oct 1.
Published in final edited form as: Behav Neurosci. 2015 Jul 27;129(5):643–655. doi: 10.1037/bne0000081

Figure 2. Mechanical and Thermal Threshold.

Figure 2

Graphs illustrate average mechanical (Panel A) and thermal (Panel B) threshold (± SD) in adult rats (PD55-56) that were exposed to different pharmacological treatment in the first two weeks of life. Morphine sulfate (10mg/kg sc twice-daily; N=24) or equivalent volume of saline (N=25 saline) was injected for 14 days starting on postnatal day 1. Hindpaw-withdrawal mechanical threshold (gram ± SD) was measured using calibrated forceps. Postnatal morphine treatment did not change the mean mechanical threshold in comparison to controls in adulthood (A). Panel B illustrates average thermal thresholds (sec ± SD), which were measured using the Hot-Plate test (52.5°C). Prolonged postnatal morphine exposure is associated with long-term thermal hypersensitivity in the adulthood in comparison to saline treated group. Two-tailed t-test: *, p<0.05.