Medical student perceptions about active methodologies in the study of physiology in medical schools in Salvador, Brazil.

In the field of medical education, it is possible to consider that the acquisition of professional competences can gain new contours when considering the use of active methodologies. It is important to analyze the perception of the students about the use of them in medical courses, as well as to reflect on their challenges and potentials. In the present study, a semistructured questionnaire of student perception was applied immediately after the execution of different types of active methodologies in the discipline of physiology in two medical courses. The results suggest a highly positive evaluation of the use of active methodologies by the student body of the two institutions. The students evaluated positively the application of the method (94.6%) and the perception about the learning (84.1%). On the other hand, when questioned about the substitution of the traditional expository method by the active methodologies, there was a tendency to the centrality of the answers, with 84.0% of the responses concentrated at positions 2, 3, and 4 on a scale of 1 (minimum) to 5 (maximum) on the Likert scale. There were no statistically significant differences when comparing variables of age, sex, and previous graduation. Although there was no consensus regarding the full replacement of traditional for active methodologies, one can conclude that the students' perception about the introduction of said methodologies in the teaching of physiology in medical courses is positive, regardless of the subgroups evaluated. These results encourage the insertion of these and other methodologies into medical courses.

Glutamate/GABA balance in ACC modulates the nociceptive responses of vocalization: an expression of affective-motivational component of pain in guinea pigs.

Evidence corroborates the role of the anterior cingulate cortex (ACC) in the modulation of cognitive and emotional functions. Its involvement in the motivational-affective component of pain has been widely investigated using different methods to elucidate the specific role of different neurotransmitter systems. We used the peripheral noxious stimulus-induced vocalization algesimetric test to verify glutamatergic and GABAergic neurotransmission in the guinea pig ACC. Microinjection of homocysteic acid (DLH; 30 nmol) in the left guinea pig ACC increased the amplitude of vocalizations (pronociception) compared to controls injected with saline. Moreover, microinjection of MK-801 (3.6 nmol), an NMDA receptor antagonist, did not alter the amplitude of vocalizations, but its microinjection prior to DLH prevented the increase in vocalizations induced by this drug. Regarding the GABAergic system, blockade of GABAA receptors with bicuculline (1 nmol) increased the amplitude of vocalizations, while three different doses of the GABAA agonist muscimol (0.5, 1 and 2 nmol) did not influence nociceptive vocalization responses. Finally, a combination of MK-801 (3.6 nmol) and muscimol (1 nmol) reduced the amplitude of vocalizations (antinociception), suggesting that a combination of glutamate and GABA in the ACC modulates the expression of affective-motivational pain response. We suggest that activation of NMDA receptors or blockade of GABAergic neurotransmission promotes pronociception and that the antinociceptive effect of muscimol depends on the blockade of NMDA receptors.

Opioidergic and GABAergic mechanisms in the rostral ventromedial medulla modulate the nociceptive response of vocalization in guinea pigs.

Vocalization generated by the application of a noxious stimulus is an integrative response related to the affective-motivational component of pain. The rostral ventromedial medulla (RVM) plays an important role in descending pain modulation, and opiates play a major role in modulation of the antinociception mediated by the RVM. Further, it has been suggested that morphine mediates antinociception indirectly, by inhibition of tonically active GABAergic neurons. The current study evaluated the effects of the opioids and GABA agonists and antagonists in the RVM on an affective-motivational pain model. Additionally, we investigated the opioidergic-GABAergic interaction in the RVM in the vocalization response to noxious stimulation. Microinjection of either morphine (4.4nmol/0.2microl) or bicuculline (0.4nmol/0.2microl) into the RVM decreased the vocalization index, whereas application of the GABA(A) receptor agonist, muscimol (0.5nmol/0.2microl) increased the vocalization index during noxious stimulation. Furthermore, prior microinjection of either the opioid antagonist naloxone (2.7nmol/0.2microl) or muscimol (0.25nmol/0.2microl) into the RVM blocked the reduction in vocalization index induced by morphine. These observations suggest an antinociceptive and pro-nociceptive role of the opioidergic and GABAergic neurotransmitters in the RVM, respectively. Our data show that opioids have an antinociceptive effect in the RVM, while GABAergic neurotransmission is related to the facilitation of nociceptive responses. Additionally, our results indicate that the antinociceptive effect of the opioids in the RVM could be mediated by a disinhibition of tonically active GABAergic interneurons in the downstream projection neurons of the descending pain control system; indicating an interaction between the opioidergic and GABAergic pathways of pain modulation.

Role of homocysteic acid in the guinea pig (Cavia porcellus) anterior cingulate cortex in tonic immobility and the influence of NMDA receptors on the dorsal PAG.

Tonic immobility (TI) is an innate defensive behaviour elicited by physical restriction and postural inversion, and is characterised by a profound and temporary state of akinesis. Our previous studies demonstrated that glutamatergic stimulation of the dorsomedial/dorsolateral portion of periaqueductal gray matter (dPAG) decreases the duration of TI in guinea pigs (Cavia porcellus). Furthermore, evidence suggests that the anterior cingulate cortex (ACC) constitutes an important source of glutamate for the dPAG. Hence, in the current study, we investigated the effects of microinjection of the excitatory amino acid (EAA) agonist DL-homocysteic acid (DLH) and the N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 into the ACC on the duration of TI in guinea pigs. We also assessed the effect of the NMDA receptor antagonist (MK-801) into the dorsal periaqueductal gray matter (dPAG) prior to DLH microinjection into the ACC on the TI duration in the guinea pig. Our results demonstrated that DLH microinjections into the ACC decreased the duration of TI. This effect was blocked by previous MK-801 microinjections into the ACC or into the dPAG. The MK-801 microinjections alone did not influence TI duration. These results provide the new insight that EAAs in the ACC can decrease the duration of TI. The mechanism seems to be dependent on the NMDA receptors present in the ACC and in the dPAG.