title: Dietary influences on morphine-induced analgesia in rats.
abstract: Morphine-induced analgesia was examined using a tail-flick apparatus in 36 adult male Sprague-Dawley rats. Rats were given ad lib access to Purina Chow alone (N = 9) or given a choice of Purina Chow and either a 0.15% saccharin solution (N = 9), a 32% sucrose solution (N = 9), or hydrogenated vegetable fat (Crisco) (N = 9). Analgesic testing was conducted immediately preceding and at 30, 60 and 90 minutes following intraperitoneal administration of morphine sulfate (0.0, 2.5, 5.0 and 10.0 mg/kg). No differences in analgesic responsiveness were observed as a function of diet preceding morphine administration. However, dietary variables did alter morphine-induced analgesia. At 30 minutes following injections of the highest dose of morphine, animals fed saccharin, sucrose or Crisco had significantly longer tail-flick latencies than rats given only Purina Chow. Sixty minutes following injections, rats fed Crisco continued to display a significantly longer tail-flick latency than rats fed only Chow. These data demonstrate that palatable substances can enhance the analgesic properties of exogenous opioids.
authors.affiliation: Department of Psychology, Tufts University, Medford, MA 02155.
authors.forename: R B
authors.initials: RB
authors.lastname: Kanarek
authors.forename: E S
authors.initials: ES
authors.lastname: White
authors.forename: M T
authors.initials: MT
authors.lastname: Biegen
authors.forename: R
authors.initials: R
authors.lastname: Marks-Kaufman
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D004041:Dietary Fats / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005247:Feeding Behavior / Q000187:drug effects; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time / Q000187:drug effects; D013649:Taste
chemical_list: D004040:Dietary Carbohydrates; D004041:Dietary Fats; D009020:Morphine