Lick rates in rats exposed to gamma-irradiation

Abstract

Lick rates in male rats were measured before, during, and after irradiation with 100 r gamma rays. No alterations in the licking renex were found. These results were interpreted as further evidence that classically conditioned saccharin aversion is not attributable to prompt neural alterations.Classical conditioned saccharin aversion, following a single simultaneous pairing of ionizing radiation and saccharin ingestion, is a well established behavioral reaction in rats (Garcia et al, 1961;. The systemic physiological concomitants produced by irradiation which are responsible for eliciting this aversion are not presently understood, but previous studies have shown that the onset of irradiation is accompanied by (1) . and (5) changes in electrical activity in the visual system (Smith & Kimeldorf, 1964). In addition, gastrointestinal dysfunction and emesis has been shown to accompany and follow exposure to ionizing radiation . Further evidence for the effects of radiation on neural tissue has been presented in Soviet reports of altered reflexive behaviors in irradiated rabbits (cf., Kimeldorf & Hunt, 1965).Previous studies have established that licking in the rat is a reflexive behavior, since mean lick rate in rats is a constant 6-7 per sec., independently of age, sex, deprivation level, and type of fluid consumed (Stellar & Hill, 1952;Schaeffer & Premack, 1961).If ionizing radiation does directly alter neural tissue and reflexive behavior, as suggested above, conditioned saccharin aversion might be explicable on the basis of some interaction of saccharin ingestion and radiation produced alterations in the licking reflex. To test for this possibility, the present study was designed. Method ROBERT W. SCHAEFFER AND JAMES C. SMITH FLORIDA STATE UNIVERSITYThe Ss were five male Sprague-Dawley rats, about 120 days old at the beginning of the experiment. They were individually housed in Hoeltge HB-ll cages, and ad lib food maintained throughout the entire experiment.The gamma radiation source was an Atomic Energy of Canada Model 150C Gamma-beam Irradiator containing 1553 Curies of C0 60. The Ss were irradiated in their home cages at a dose rate of 1.3 r/min. for 76 min., with an approximate total dose of 100 r. Lick rates were measured by drinkometers and recorded by an Esterline Angus digital recorder on tape moving at 1.9 crolsec.All Ss were originally ad lib maintained on water for four weeks, then 23 hr. water deprived and presented with a 0.1% saccharin solution for 76 min. daily for four consecutive days, with 23 hr. intervening between each successive saccharin presentation. Procedurally, the first saccharin presentation constituted a sham exposure, and the third and fourth saccharin presentations were equivalent to the typical postirradiation saccharin preference tests (cf., Smith & Schaeffer, 1966). The gamma irradiation coincided with the second saccharin presentation. Results and DiscussionMomentary lick rates were determined for each S, sec. by sec., throughout each of the four saccharin test periods. The ...

EFFECTS OF RADIATION ON THE BEHAVIOR OF ANIMALS: A REVIEW OF THE LITERATURE. Appendix to 1972 Progress Report.

“…This, he feels, supports the hypothesis that radiation detection and radiation induced aversions rely on the same mediating mechanism involving the central nervous system. Since the mean lick rates and the lick rate ranges did not vary with x-ray exposure in rats even when saccharin aversion was induced, the saccharin aversion cannot be attributed to prompt neural alterations (Schaeffer and Smith, 1966). feel that radiation-induced aversion is a form of discrimination learning since the requirements for this establishment are a distinctive fluid paired with radiation exposure and an alternative fluid which has not been paired with radiation treatment.…”

Differential reinforcement of specific lick rates in the rat

“…As have other investigators , however , they found that both the mean and modal lick rates for rats were 6·7 licks/sec. Further evidence for the highly invariant , elicited, reflexive nature of licking in the rat has been provided by Snyder & Hulse (1961), DeBold , Miller, & Jensen (1965), Boice & Denny (1965), Hulse (1966), and Schaeffer & Smith (1966). These studies, in addition to revealing that the lick response fatigued , could be classically conditioned , and , once init iated, was reflexive, all reported that lick rate was essentially constant.…”

“…As have other investigators , however , they found that both the mean and modal lick rates for rats were 6·7 licks/sec. Smith (1966). These studies, in addition to revealing that the lick response fatigued , could be classically conditioned , and , once init iated, was reflexive, all reported that lick rate was essentially constant.…”

“…These studies, in addition to revealing that the lick response fatigued , could be classically conditioned , and , once init iated, was reflexive, all reported that lick rate was essentially constant. Furthermore, the reflexive properties of momentary lick rate were not affected by radiation doses 10 times the strength needed to produce aversion to normally preferred saccharin solutions (Schaeffer & Smith, 1966).…”

“…These studies, in addition to revealing that the lick response fatigued , could be classically conditioned , and , once init iated, was reflexive, all reported that lick rate was essentially constant. Furthermore, the reflexive properties of momentary lick rate were not affected by radiation doses 10 times the strength needed to produce aversion to normally preferred saccharin solutions (Schaeffer & Smith, 1966).Recently, Corbit & Luschei (1969) used a computer to measure interlick intervals in milliseconds and found that neither different deprivation schedules, preferred taste stimulation, nor aversive taste stimulation affected the interlick interval. The mean rate of licking , as measured by this highly precise method , equalled 6.5 licks/sec, which compares favorably with the rates found by earlier investigators, using considerably less precise instrument ation than the computer.…”