El Homo sapiens, la fe y el efecto placebo / Homo sapiens, faith and the placebo effect

Los llamados efecto placebo y nocebo son efectos reales que resultan de la interacción entre la actividad mental y el estado funcional del organismo. Esta interacción se puede describir hoy en términos precisos a través de la influencia que las estructuras del sistema límbico ejercen sobre el hipotálamo y las regiones del tallo cerebral que controlan las funciones endocrina, motora y vegetativa. El conocimiento de estos mecanismos pone de relieve la importancia de factores sugestivos, como la confianza en el terapeuta o en el tratamiento indicado, en la curación de enfermedades o de sus secuelas. Existen evidencias de que algunas terapias sin una base científica sólida como la acupuntura, la homeopatía o la terapia floral, logran sus resultados a través de estos mecanismos. Incorporar los principios psicobiológicos que origina el efecto placebo a la relación médico paciente, puede resultar una contribución positiva para una medicina más efectiva y humana, pero siempre dentro de los límites que imponen la ética de no mentir y el respeto a la integridad e inteligencia de los pacientes

The so called placebo and nocebo effects are real, and result from the interaction between the mental activity and the functioning of the body. This interaction is presently described in precise terms as the influence exerted by limbic structures on the hypothalamus and on the brain stem's nuclei that control the endocrine, motor and vegetative functions. Understanding of these mechanisms discloses the important role played by suggestion, like trusting your therapist or trusting the treatment, in the cure of diseases and their sequels. There is also evidence that therapies without a strong scientific foundation, like acupuncture, homeopathy or flower therapy, can achieve some results based on these mechanisms. The introduction of the psychobiological principles governing the effect of placebo into the medical practice could contribute to a more effective and human medicine, provided that the ethical limits imposed by the truth and the respect to the patient´s integrity and intelligence are observed

Deptal fetal tissue transplants restore long-term potentiation in the dentate gyrus of fimbria-fornix-lesioned rats

Two groups of Sgrague-Dawley male rats received bilateral aspirative lesions of the fimbria fornix under chloral hydrate anesthesia. One group (n=9) received no further treatment (lesioned). In the second group (n=8), a piece of septal fetal tissue, obtained at day E15-16, was implanted into each lesion cavity (transplanted). A third group consisted of sham-lesioned rats (controls, n=14). Two months after the operations, a recording electrode was implanted in the hilar region of the dentate gyrus of each animal, and a bipolar stimulating electrode was implanted in the perforant path. Long-term potentiation at 400 Hz was induced and followed for two hours. FF-lesioned rats showed and impaired potentiation of the field excitatory post-synaptic potential, which rapidly declined to basal levels within 15 minutes. The transplanted rats showed a normal potentiation of this parameter, similar to that seen in the control animals. A decrease in choline acetyltransferase activity in the hippocampi of the lesioned animals showed a tendency toward recovery after septal fetal tissue transplantation. In all the dorsal hippocampal areas of the lesioned animals, acetylcholinesterase histochemistry showed an almost complete loss of enzymatic activity, which was partially restored by the transplants. The improved synaptic plasticity in the transplanted animals might be related to septal transplant-induced recovery of mnemonic functions

Chronic intraventricular infusion with NGF improves LTP in old cognitively-impaired rats

Aged (21 months) cognitively-impaired male Sprague Duwley rats received intraventricular infusion of nerve growth factor (NGF) or cytochrome C (Cit C) for 14 or 28 days using miniosmotic pumps and were evaluated either 1 week or 3 months after treatment. Groups of untreated young, aged-impaired and aged non-impaired rats were also evaluated. Under narcose recording and stimulating electrodes were stereotactically implanted in the dentate gyrus and the perforant path. The stimulation intensity was individually adjusted to obtain a half-maximal population spike (P) for test stimuli and a quarter-maximal for tetanization. The amplitude and latency of P and the slope (S) of the field EPSP were determinated before and at 2, 5, 15, 30 and 60 min after tetanization at 400 Hz. Paired stimuli at 30 ms inerval were also applied before and afeter tetanization. Aged, cognitively impaired rats showed an absent S potentiation and a delayed P potentiation, both in amplitude and latency, while non-impaired rats behaved like the young controls. Paired pulse inhibition showed no difference among groups before or after tetanization suggesting that the impaired potentiation is not due to an increased retroactive inhibition. NGF treatment ameliorates LTP deficits to levels equivalent to non-impaired rats, while Cit C controls showed no improvement. No differences appear among NGF treated groups, but evidence suggest that the animals evaluated 3 months after treatment developed a stronger potentiation