Brain research
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The lateral parabrachial nucleus (LPBN) and the central nucleus of the amygdala (CeA) are important central areas for the control of sodium appetite. In the present study, we investigated the importance of the facilitatory mechanisms of the CeA on NaCl and water intake produced by the deactivation of LPBN inhibitory mechanisms. Male Holtzman rats (n=7-14) with stainless steel cannulas implanted bilaterally in the CeA and LPBN were used. ⋯ Euhydrated rats treated with muscimol (0.5 nmol/0.2 μl) into the LPBN also ingested 0.3M NaCl (19.1 ± 6.4 ml/4h) and water (8.8 ± 3.2 ml/4h). Muscimol (0.5 nmol/0.2 μl) into the CeA also abolished 0.3M NaCl (0.1 ± 0.04 ml/4h) and water intake (0.1 ± 0.02 ml/4h) in euhydrated treated with muscimol into the LPBN. The present results show that neuronal deactivation of the CeA abolishes NaCl intake produced by the blockade of LPBN inhibitory mechanisms, suggesting an interaction between facilitatory mechanisms of the CeA and inhibitory mechanisms of the LPBN in the control of NaCl intake.
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The trigeminovascular system has a pivotal role in the pathomechanism of migraine. The aim of the present study was to further develop existing models of migraine making them more suitable for testing the effects of compounds with presumed antimigraine activity in anaesthetised rats. Simultaneous recording of ongoing activity of spontaneously active neurons in the trigeminocervical complex as well as their discharges evoked by electrical stimulation of the dura mater via activation of A- and C-sensory fibres were carried out. ⋯ Nevertheless, inhibitory effect of propranolol and topiramate was evident when considering A- or C-fibre responses. Findings do not support the view that electrically evoked responses are useful for the measurement of trigeminal sensitization. It is proposed however, that inhibition of enhanced firing (immediate and/or delayed) evoked by inflammatory mediators as an endpoint have higher predictive validity regarding the clinical effectiveness of compounds.