Cocaine and food deprivation : effects on food-reinforced fixed-ratio performance in pigeons /

Abstract

Key pecking by 6 pigeons was maintained by a fixed-ratio 30 schedule of food presentation while body weights were 80% of free-feeding weights. Acute administration of cocaine (0.3 to 13.0 mg/ kg, i.m.) dose-dependently decreased response rates. Dose-effect curves were shifted to the right when 3 of the 6 pigeons were maintained at 70% of free-feeding weights and were shifted to the left when the other 3 pigeons were maintained at 90% of free-feeding weights. Then a dose of cocaine that initially decreased response rates by more than 95% of control rates was administered before each daily session. Comparable degrees of tolerance to these rate-decreasing effects developed in the two groups. The rate at which responding recovered was relatively rapid for pigeons in the 70% free-feeding-weight group and was slower for 2 of the 3 pigeons in the 90% free-feeding-weight group. When body weights were then increased from 70% to 80% or were decreased from 90% to 80% of free-feeding weight, performance was disrupted initially only for pigeons whose weight went from 70% to 80% of free feeding. In the present experiment the degree of deprivation may have indirectly influenced the degree of tolerance that developed to cocaine's response rate-decreasing effects because it directly influenced the dose chosen to be administered chronically. The degree of deprivation appeared to have a more direct influence on the rate at which tolerance developed.

Morphine Tolerance as a Function of Ratio Schedule: Response Requirement or Unit Price?

“…Therefore, the ''strength'' of baseline responding, as indexed by the initial disruption by the drug, could be a predictor of tolerance development (cf., Hoffman et al, 1987). In another experiment, pigeons were maintained at different levels of food deprivation (Hughes, Pitts, & Branch, 1996). The ratedecreasing effects of cocaine were attenuated and exacerbated when pigeons were maintained at a lower level or higher level of food deprivation, respectively.…”

Food‐deprivation Level Alters the Effects of Morphine on Pigeons' Key Pecking

“…The effects of drugs on behavior are altered in several ways by level of food deprivation. The rate-decreasing effects of higher doses of psychomotor stimulants are lessened with increasing deprivation (Cole, 1967;Gollub & Mann, 1969;Hughes, Pitts, & Branch, 1996;Samson, 1986;Schaal & Branch, 1992;Schaal, Miller, & Odum, 1995). Increased food deprivation also has been shown to enhance the rate-increasing effects of low doses of cocaine (Schaal et al, 1995).…”

“…The decreased ability of large doses of psychomotor stimulants such as d-amphetamine and cocaine to suppress rates of food-maintained behavior when subjects are more severely deprived is well documented (e.g., Cole, 1967;Gollub & Mann, 1969;Hughes et al, 1996;Samson, 1986;Schaal & Branch, 1992;Schaal et al, 1995). However, the effects of opioids on operant behavior under different levels of deprivation have received little investigation (but see Kelly & Thompson, 1988).…”

Role of dose order in the development of tolerance to effects of cocaine on schedule-controlled behavior in pigeons

“…Such a regimen might promote tolerance by allowing subjects to "recover" from large-dose effects by having less effective doses follow. It should also be noted that, in their study, each series of doses included one exposure to the drug vehicle, and there are data to suggest that occasional sessions with vehicle present may promote tolerance to the behavioral effects of cocaine (Hughes et al 1996). These possibilities, as well as the advisability of examining the generality of effects of variable dosing, indicate that examination of dose order in variable dosing is warranted.…”