From my individual standpoint, I suppose, in many cases, there is no exact correlation between the dosages and ways of administration, that means the dosage, concentration or volume used in different ways may be quite different with each other. In addition, different organs, different animal strains, different genders, different ages, different time points may even have various applying dosages.
However, definitely, that does not mean all the drugs can not be converted each other among different ways of administration. At least, so far, I don't know yet (its not my field, we hope we can get some more details by some experts who have been involving in this area).
Therefore, when we don't exactly know the dosage of the drugs which will be used, I prefer to choose it which had been applied by the former experimenters in our lab or in the authoratively published articles. Even so, I just choose this as a reference or a guide to our own practical experience. Because sometimes things may not always the same since the time and people changed. So we need to do some short pre-experiments to confirm it, then we can use it undoubtedly in our own studies.
Below is a reference may be related with your topic or may not, you can choose it by your own justice. Hope this will give you some tips. Thanks for your time! Good luck!
Research Dose-response characteristics of methylphenidate on locomotor behavior and on sensory evoked potentials recorded from the VTA, NAc, and PFC in freely behaving rats Pamela B Yang1,2 , Alan C Swann2 and Nachum Dafny1
1 Department of Neurobiology and Anatomy, The University of Texas-Medical School at Houston, P.O. Box 20708, Houston, Texas 77225, USA
2 Department of Psychiatry and Behavioral Sciences, The University of Texas-Medical School at Houston, P.O. Box 20708, Houston, Texas 77225, USA
Behavioral and Brain Functions 2006, 2:3doi:10.1186/1744-9081-2-3
Abstract Background Methylphenidate (MPD) is a psychostimulant commonly prescribed for attention deficit/hyperactivity disorder. The mode of action of the brain circuitry responsible for initiating the animals' behavior in response to psychostimulants is not well understood. There is some evidence that psychostimulants activate the ventral tegmental area (VTA), nucleus accumbens (NAc), and prefrontal cortex (PFC).
Methods The present study was designed to investigate the acute dose-response of MPD (0.6, 2.5, and 10.0 mg/kg) on locomotor behavior and sensory evoked potentials recorded from the VTA, NAc, and PFC in freely behaving rats previously implanted with permanent electrodes. For locomotor behavior, adult male Wistar-Kyoto (WKY; n = 39) rats were given saline on experimental day 1 and either saline or an acute injection of MPD (0.6, 2.5, or 10.0 mg/kg, i.p.) on experimental day 2. Locomotor activity was recorded for 2-h post injection on both days using an automated, computerized activity monitoring system. Electrophysiological recordings were also performed in the adult male WKY rats (n = 10). Five to seven days after the rats had recovered from the implantation of electrodes, each rat was placed in a sound-insulated, electrophysiological test chamber where its sensory evoked field potentials were recorded before and after saline and 0.6, 2.5, and 10.0 mg/kg MPD injection. Time interval between injections was 90 min.
Results Results showed an increase in locomotion with dose-response characteristics, while a dose-response decrease in amplitude of the components of sensory evoked field responses of the VTA, NAc, and PFC neurons. For example, the P3 component of the sensory evoked field response of the VTA decreased by 19.8% ± 7.4% from baseline after treatment of 0.6 mg/kg MPD, 37.8% ± 5.9% after 2.5 mg/kg MPD, and 56.5% ± 3.9% after 10 mg/kg MPD. Greater attenuation from baseline was observed in the NAc and PFC. Differences in the intensity of MPD-induced attenuation were also found among these brain areas.
Conclusion These results suggest that an acute treatment of MPD produces electrophysiologically detectable alterations at the neuronal level, as well as observable, behavioral responses. The present study is the first to investigate the acute dose-response effects of MPD on behavior in terms of locomotor activity and in the brain involving the sensory inputs of VTA, NAc, and PFC neurons in intact, non-anesthetized, freely behaving rats previously implanted with permanent electrodes.
