RESUMO
There is increasing concern about the neurodegenerative and behavioral consequences of ozone pollution in industrialized urban centers throughout the world and that women may be more susceptible to brain neurodegenerative disorders. In the present study we have investigated the effects of chronic (30 or 60 days) exposure to ozone on olfactory perception and memory and on levels of lipid peroxidation, alpha and beta estrogen receptors and dopamine beta-hydroxylase in the olfactory bulb in ovariectomized female rats. The ability of 17beta-estradiol to prevent these effects was then assessed. Results showed that ozone exposure for 30 or 60 days impaired formation/retention of a selective olfactory recognition memory 120 min after exposure to a juvenile stimulus animal with the effect at 60 days being significantly greater than at 30 days. They also showed impaired speed in locating a buried chocolate reward after 60 days of ozone exposure indicating some loss of olfactory perception. These functional impairments could all be prevented by coincident estradiol treatment. In the olfactory bulb, levels of lipid peroxidation were increased at both 30- and 60-day time-points and numbers of cells with immunohistochemical staining for alpha and beta estrogen receptors, and dopamine beta-hydroxylase were reduced as were alpha and beta estrogen receptor protein levels. These effects were prevented by estradiol treatment. Oxidative stress damage caused by chronic exposure to ozone does therefore impair olfactory perception and social recognition memory and may do so by reducing noradrenergic and estrogen receptor activity in the olfactory bulb. That these effects can be prevented by estradiol treatment suggests increased susceptibility to neurodegenerative disorders in aging women may be contributed to by reduced estrogen levels post-menopause.
Assuntos
Estradiol/uso terapêutico , Estrogênios/uso terapêutico , Peroxidação de Lipídeos/efeitos dos fármacos , Transtornos da Memória/tratamento farmacológico , Bulbo Olfatório/efeitos dos fármacos , Ozônio/toxicidade , Poluentes Atmosféricos , Animais , Dopamina beta-Hidroxilase/metabolismo , Receptor alfa de Estrogênio/metabolismo , Receptor beta de Estrogênio/metabolismo , Feminino , Transtornos da Memória/induzido quimicamente , Percepção Olfatória/efeitos dos fármacos , Ovariectomia , Estresse Oxidativo/efeitos dos fármacos , Ratos , Ratos Wistar , Reconhecimento Psicológico/efeitos dos fármacos , Percepção SocialRESUMO
The ability of vaginocervical stimulation (VCS) to promote olfactory social recognition memory at different stages of the ovarian cycle was investigated in female rats. A juvenile social recognition paradigm was used and memory retention tested at 30 and 300 min after an adult was exposed to a juvenile during three 4-min trials. Results showed that an intact social recognition memory was present at 30 min in animals with or without VCS and at all stages of the estrus cycle. However, whereas no animals in any stage of the estrus cycle showed retention of the specific recognition memory at 300 min, those in the proestrus/estrus phase that received VCS 10 min before the trial started did. In vivo microdialysis studies showed that there was a significant release of oxytocin after VCS in the olfactory bulb during proestrus. There was also increased oxytocin immunoreactivity within the olfactory bulb after VCS in proestrus animals compared with diestrus ones. Furthermore, when animals received an infusion of an oxytocin antagonist directly into the olfactory bulb, or a systemic administration of alpha or beta noradrenaline-antagonists, they failed to show evidence for maintenance of a selective olfactory recognition memory at 300 min. Animals with vagus or pelvic nerve section also showed no memory retention when tested after 300 min. These results suggest that VCS releases oxytocin in the olfactory bulb to enhance the social recognition memory and that this may be due to modulatory actions on noradrenaline release. The vagus and pelvic nerves are responsible for carrying the information from the pelvic area to the CNS.
Assuntos
Memória/fisiologia , Bulbo Olfatório/metabolismo , Ocitocina/metabolismo , Reconhecimento Psicológico/fisiologia , Olfato/fisiologia , Comportamento Social , Antagonistas Adrenérgicos/farmacologia , Animais , Colo do Útero/inervação , Colo do Útero/fisiologia , Ciclo Estral/fisiologia , Feminino , Plexo Hipogástrico/anatomia & histologia , Plexo Hipogástrico/fisiologia , Imuno-Histoquímica , Neurônios Aferentes/metabolismo , Norepinefrina/metabolismo , Ocitocina/antagonistas & inibidores , Estimulação Física , Ratos , Ratos Wistar , Transmissão Sináptica/fisiologia , Vagina/inervação , Vagina/fisiologia , Nervo Vago/anatomia & histologia , Nervo Vago/fisiologia , Fibras Aferentes Viscerais/anatomia & histologia , Fibras Aferentes Viscerais/fisiologiaRESUMO
Long-term potentiation (LTP) is considered a cellular correlate of memory processing. A short-lasting early-LTP can be prolonged into a late-L TP (>4h) by stimulation of the basolateral amygdala (BLA) or motivational behavioral stimuli in young, but not in aged, cognitively impaired rats. We measured the changes in transmitter release-induced by BLA or behavioral reinforcement-in young and aged cognitively impaired rats, after implanting a microdialysis cannula at the dentate gyrus. Samples were taken under baseline conditions and during stimulation of BLA. Rats were water deprived and tested again next day, taking samples after allowing access to water. Higher concentrations of choline, HIAA, aspartate, glutamate, and glycine were found in baseline samples from young animals compared to aged. In young animals, BLA stimulation increased the levels of ACh and reduced norepinephrine and serotonine, while behavioral reinforcement reduced the levels of glutamate and glycine. These effects were absent among aged rats, suggesting that this reduced neurochemical response might be linked to the impaired LTP-reinforcement reported previously.
Assuntos
Envelhecimento/fisiologia , Giro Denteado/metabolismo , Potenciação de Longa Duração/fisiologia , Neurotransmissores/metabolismo , Acetilcolina/metabolismo , Animais , Ácido Aspártico/metabolismo , Colina/metabolismo , Ácido Glutâmico/metabolismo , Glicina/metabolismo , Ácido Hidroxi-Indolacético/análise , Microdiálise , Norepinefrina/metabolismo , Ratos , Ratos Sprague-Dawley , Serotonina/metabolismo , Transmissão Sináptica/fisiologiaRESUMO
The effects of vaginocervical stimulation (VCS) on glutamate (GLU), aspartate (ASP), gamma-aminobutyric acid (GABA), noradrenaline (NA), arginine (ARG) and nitric oxide (NO) (citrulline) release in the nucleus of the solitary tract (nTS) were measured in anaesthetised female rats as a function of the oestrus cycle. During pro-oestrus/oestrus (P/E), but not during met-oestrus/di-oestrus (M/D), VCS significantly increased concentrations of NA, ASP, GLU, NO (citrulline) and GABA, but not ARG. Basal NA concentrations were also increased in P/E. These effects were prevented by bilateral section of either the vagus nerve or pelvic and hypogastric nerves. Vagotomy also significantly decreased basal NO concentrations in M/D and P/E while pelvic and hypogastric nerve section significantly increased GABA concentrations. Our results therefore confirm that the nTS is a relay structure for the visceral afferents sending information from the uterus into the central nervous system. The ability of VCS to trigger classical transmitter release and NO in the female is influenced by the stage of the oestrous cycle and is routed both via the vagus and pelvic/hypogastric nerves.