Peculiar response to methylphenidate in adolescent compared to adult rats: a phMRI study

• Published in: Psychopharmacologia Vol. 203; no. 1; pp. 143 - 153
• Main Authors: Canese, Rossella, Adriani, Walter, Marco, Eva M., De Pasquale, Francesco, Lorenzini, Paola, De Luca, Nicoletta, Fabi, Fulvia, Podo, Franca, Laviola, Giovanni
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.03.2009; Springer; Springer Nature B.V
• Subjects: Age; Age Factors; Animals; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Blood Pressure - drug effects; Brain; Brain - blood supply; Brain - drug effects; Brain - growth & development; Brain Mapping - methods; Central Nervous System Stimulants - pharmacology; Cerebrovascular Circulation - drug effects; Heart Rate - drug effects; Hippocampus - blood supply; Hippocampus - drug effects; Magnetic Resonance Imaging; Male; Medical sciences; Methylphenidate - pharmacology; Neurons - drug effects; Neuropharmacology; Neurosciences; Nucleus Accumbens - blood supply; Nucleus Accumbens - drug effects; Original Investigation; Pharmacology. Drug treatments; Pharmacology/Toxicology; Prefrontal Cortex - blood supply; Prefrontal Cortex - drug effects; Psychiatry; Psychoanaleptics: cns stimulant, antidepressant agent, nootropic agent, mood stabilizer; Psychoanaleptics: cns stimulant, antidepressant agent, nootropic agent, mood stabilizer..., (alzheimer disease); Psychology. Psychoanalysis. Psychiatry; Psychopharmacology; Psychotropic drugs; Rats; Rats, Sprague-Dawley; Rodents; Time Factors; Psycho-stimulant; BOLD; Age-dependent; phMRI; Brain development; Rat; CNS stimulant; Psychotropic; Rodentia; Central nervous system; Age criterion; Experimental study; Encephalon; Vertebrata; Mammalia; Animal; Piperidine derivatives; Adult animal; Development; Comparative study; Methylphenidate
• ISSN: 0033-3158; 1432-2072
• DOI: 10.1007/s00213-008-1379-1

Rationale Adolescent rodents differ markedly from adults in several neuro-behavioural parameters. Moreover, ‘paradoxical’ responses to psychostimulants have been reported at this age. Objectives Thus, we investigated the responses of adolescent (post-natal day, PND, 34 to 43) and adult (PND >60) Sprague–Dawley male rats to the psychostimulant drug methylphenidate (MPH). We used pharmacological magnetic resonance imaging (phMRI) performed at 4.7 T under isoflurane anaesthesia. Following anatomical MRI, axial gradient echo images were collected continuously. After baseline recording (32 min), animals received MPH (0 or 4 mg/kg i.p.) and were recorded for further 32 min. Results Region-specific changes in the blood-oxygenation level dependent (BOLD) signal were evident as a function of age. As expected, among adults MPH induced an increase of BOLD signal in nucleus accumbens (NAcc) and prefrontal cortex (PFC), with no effects in the hippocampus (Hip). Notably, among adolescents, MPH induced a marked and generalised decrease of BOLD signal, which occurred earlier in NAcc and PFC whilst being delayed in the Hip. Any bias in BOLD responses was excluded by the measurement of physiological parameters. Conclusions The present findings highlight the utility of phMRI in animal models. The peculiar negative BOLD effect found in adolescent rats may be suggestive of a reduced cerebro-vascular feedback and/or an increased MPH-induced neuronal activation. Data are relevant for a better understanding of brain/behavioural regulation during adolescent development. Moreover, a greater understanding of the differences between adult and adolescent drug responses will aid in the development of a more appropriate age-specific treatment strategy.