Age differences to methylphenidate-NAc neuronal and behavioral recordings from freely behaving animals.

Methylphenidate (MPD) is a psychostimulant that is widely prescribed to treat attention deficit-hyperactivity disorder, but it is abused recreationally as well. The nucleus accumbens (NAc) is part of the motivation circuit implicated in drug-seeking behaviors. The NAc neuronal activity was recorded alongside the behavioral activity from young and adult rats to determine if there are significant differences in the response to MPD. The same dose of MPD elicits behavioral sensitization in some animals and behavioral tolerance in others. In adult animals, higher doses of MPD resulted in a greater ratio of tolerance/sensitization. Animals who responded to chronic MPD with behavioral sensitization usually exhibited further increases in their NAc neuronal firing rates as well. Different upregulations of transcription factors (ΔFOSB/CREB), variable proportions of D1/D2 dopamine receptors, and modulation from other brain areas may predispose certain animals to express behavioral and neuronal sensitization versus tolerance to MPD.

Recruitment of neurons in basolateral amygdala after intense training produces a stronger memory trace.

Typical amnestic treatments are ineffective when administered to subjects trained in aversively-motivated tasks using relatively high foot-shock intensities. This effect has been found when treatments that disrupt neuronal activity are administered to different regions of the brain, including the amygdala. However, the molecular mechanisms induced by this intense training are unknown. We made a detailed mapping of c-Fos-expressing neurons in four regions of the amygdala after moderate and intense one-trial inhibitory avoidance training. Rats were sacrificed 90 min after training or after appropriate control procedures, and their brains were prepared for immunohistochemical c-Fos protein detection in the central, lateral, and in the anterior and posterior parts of the basolateral amygdaloid nucleus. We found a high percentage of neurons expressing c-Fos in the anterior part of the basolateral nucleus after moderate training, and this percentage increased further after intense training. Moderate and intense training did not induce changes in c-Fos expression in the other explored amygdaloid regions. These results show that inhibitory avoidance training produces a localized expression of c-Fos in the basolateral anterior nucleus of the amygdala, which is dependent upon the intensity of training, and indicate that synaptic plastic changes in this region may be required for the formation of memory of moderate and intense aversive learning.

Adolescent rats respond differently to methylphenidate as compared to adult rats- concomitant VTA neuronal and behavioral Recordings.

Methylphenidate (MPD) is the most widely prescribed psychostimulant used in adolescents and adults to treat attention-deficit/hyperactivity disorder (ADHD). The recreational use of MPD is becoming more prevalent because of its ability to improve cognitive enhancement. The ventral tegmental area (VTA) of the brain is highly associated with reward, cognition and addiction to drugs including psychostimulants like MPD. The VTA neuronal activity was recorded alongside the horizontal behavioral activity from freely behaving non-anesthetized rats. Four adolescent and four adult groups were treated with either saline, 0.6, 2.5 or 10.0 mg/kg MPD. In both adolescent and adult animals, the animals responded to MPD in a dose-dependent manner, such that as the dose of MPD increased, more animals and more VTA unit responded to the drug. The same doses of MPD elicited in some animals behavioral and neuronal sensitization and in other animals behavioral and neuronal tolerance. In the 0.6 and 10.0 mg/kg MPD dose groups there were significant differences between the age groups for how many animals expressed behavioral sensitization and behavioral tolerance to chronic MPD exposure. Additionally, the animal's behavioral response to MPD by excitation or attenuation of activity did not always correlate to the VTA neuronal response, and the age group with significantly higher behavioral responses did not always correlate to the age group with significantly higher VTA neuronal responses for a given MPD dose. These findings differ from similar studies recorded from the prefrontal cortex (PFC), which exhibited behavioral responses continuously directly correlated to PFC responses for increasing MPD doses. This demonstrates that unlike other areas of the brain, there is not a direct relationship between VTA firing and behavioral activity, suggesting that there is input or modulation of this area from elsewhere in the brain. Further investigation is needed to clearly understand the relationship between VTA firing rates and behavioral responses to different MPD doses, especially given the significant differences in response between young and adult animals and the increasing use of the drug in adolescent populations.

Dental treatment for children with chronic idiopathic thrombocytopaenic purpura: a report of two cases.

Idiopathic thrombocytopaenic purpura (ITP) is the most common acquired bleeding disorder occurring in previously healthy children. The condition is benign and self-limiting, with a high possibility of recovery. Only 15-30% of children with acute ITP develop the chronic form. Clinically, ITP presents with petechiae, ecchymoses, haematomas, epistaxis, haematuria, mucocutaneous bleeding, and occasionally, haemorrhage into tissues. Oral manifestations include spontaneous gingival bleeding, petechiae or haematomas of the mucosa, tongue or palate. Two paediatric case reports are described concerning female patients diagnosed with chronic ITP. Oral findings and dental procedures are described. Standard dental treatment was performed with a platelet count higher than 50,000/mm3. The importance of adequate dental plaque control techniques in order to prevent inflammation, potential bleeding and infection in these patients is emphasized. The paediatric dentist must be aware of the clinical appearance of ITP in order to recognize the condition and successfully manage the patient.

Factitial oral lesions in an autistic paediatric patient.

Self Injurious Behaviour (SIB) is a deliberate harm to the body that may lead to factitial injuries. Its origin may be functional or biological and it has a higher prevalence in females and in psychologically impaired individuals. Seventy per cent of autistic patients have SIB. Seventy-five per cent of factitial injuries are located in the head and neck region. A paediatric case report concerning a 4-year-old autistic female is presented. Detailed medical history, physical examination, clinical intraoral and radiographic examination, incisional biopsy, neuropaediatrical, psychological and speech evaluation were undertaken. Diagnosis included hypochromic macrocytic anaemia, caries, coronal fracture, factitial ulcer, factitial periodontitis, self-extraction of primary teeth and permanent teeth buds, non-specific oral ulcer with inflammatory reaction, mild mental retardation, speech impairment, autistic syndrome and self injurious behaviour consisting of putting fingers and foreign objects in the gingiva, fingernail biting and hair pulling. Differential diagnosis included hystiocitosis X, prepuberal periodontitis and leukocyte adhesion deficiency. Dental preventive and restorative treatment was performed. Non-contingent reinforcement therapy was successfully used to diminish SIB. Treatment of factitial oral injuries must be interdisciplinary and requires cooperation of the patient, the parents, health care providers, and medical team.