Abstract
Adrenalectomy affects analgesic responses differentially, potentiating morphine and cold-water swim analgesia while reducing prolonged, intermittent foot shock analgesia. Adrenocortical influences also exhibit differential effects: dexamethasone pretreatment potentiates morphine analgesia while reducing both forms of stress-induced analgesia. In assessing sympathomedullary influences in analgesic processes, adrenal demedullation reduces prolonged, intermittent foot shock analgesia. The present study examined the effects of adrenal demedullation both with (MADX/6-OHDA) and without (MADX) peripheral 6-hydroxydopamine injections upon the analgesic responses following 2°C and 15°C swims and following 5 mg/kg and 2.5 mg/kg doses of morphine. Significant reductions were observed in adrenal epinephrine levels in all MADX rats and in heart norepinephrine levels in MADX/6-OHDA rats. Despite the adrenal demedullation and sympathetic dennervation, neither the MADX group nor the MADX/6-OHDA group differed significantly from sham control rats in their baseline post-operative or post-injection flinch-jump thresholds, in their analgesic responses following the 2°C and 15°C swims, or in their analgesic responses following the 5 mg/kg and 2.5 mg/kg morphine doses. These data are assessed in terms of divergent adrenal influences upon various analgesic responses.
Original language | English (US) |
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Pages (from-to) | 1105-1109 |
Number of pages | 5 |
Journal | Physiology and Behavior |
Volume | 29 |
Issue number | 6 |
DOIs | |
State | Published - Dec 1982 |
Externally published | Yes |
Keywords
- 6-Hydroxydopamine
- Adrenal demedullation
- Adrenocortical response
- Morphine analgesia
- Stress-induced analgesia
- Sympathomedullary response
ASJC Scopus subject areas
- Experimental and Cognitive Psychology
- Behavioral Neuroscience