NMDA-glutamatergic activation of the ventral tegmental area induces hippocampal theta rhythm in anesthetized rats.

Glutamate afferents reaching the ventral tegmental area (VTA) affect dopamine (DA) cells in this structure probably mainly via NMDA receptors. VTA appears to be one of the structures involved in regulation of hippocampal theta rhythm, and this work aimed at assessing the role of glutamatergic activation of the VTA in the theta regulation. Male Wistar rats (n=17) were divided into groups, each receiving intra-VTA microinjection (0.

Locomotor response to novelty correlates with differences in number and morphology of hypothalamic tyrosine hydroxylase positive cells in rats.

Individual differences in the intensity of locomotor response to a new environment (exploratory reaction) are generally used as a model to study individual vulnerability to stress and drug addiction. In the present work we studied the number, distribution and morphology of the hypothalamic cells expressing tyrosine hydroxylase (TH+ cells) (immunohistochemical and immunofluorescent staining) in male Wistar rats divided based on high (HR), midline (MR) or low (LR) locomotor activity in response to novelty. Morphology and total number of TH+ cells were analyzed for A11-A15 dopaminergic groups.

Hippocampal theta rhythm induced by rostral pontine nucleus stimulation in the conditions of pedunculopontine tegmental nucleus inactivation.

Theta rhythm in rat hippocampus occurs during cortical activation in different forms of waking as well as during paradoxical phase of sleep. The multi-level regulatory system of theta, based mainly on cholinergic transmission, includes structures from the forebrain to the medulla. Among them the most important are two reticular nuclei: the pedunculopontine tegmental nucleus (PPN) and rostral pontine tegmental nucleus (RPO).

Dopaminergic transmission in the midbrain ventral tegmental area in the induction of hippocampal theta rhythm.

Hippocampal rhythmic slow activity (RSA, theta) is regulated by many brainstem structures, including the midbrain ventral tegmental area (VTA). This work aimed at assessing the role of the dopaminergic (DA) transmission of the VTA in this regulation. Male Wistar rats (n=35) in urethane anaesthesia received an intra-VTA microinjection of either flupenthixol (FLU; doses of 5.

Induction of hippocampal theta rhythm by electrical stimulation of the ventral tegmental area and its loss after septum inactivation.

The ventral tegmental area (VTA), which may be one of the structures involved in regulation of hippocampal theta rhythm, sends direct projections to the hippocampus and also to the forebrain septum, the key centres involved in theta generation. In the present study we aimed at assessing which projections from the VTA (direct or through the septum) participate in regulation of hippocampal electric activity. Experiments were conducted on 3 groups of urethanised male Wistar rats.

Involvement of GABAergic transmission in the midbrain ventral tegmental area in the regulation of hippocampal theta rhythm.

Previously we indicated that the ventral tegmental area (VTA) may belong to the system regulating hippocampal theta rhythm. In the present study, we aimed at assessing the role of the GABAergic system of the VTA in regulation of hippocampal electric activity. Male Wistar rats received unilateral intra-VTA microinjection of either bicuculline (50ng/0.

Modulation of hippocampal theta rhythm by the opioid system of the pedunculopontine tegmental nucleus.

The pedunculopontine tegmental nucleus (PPN) belongs to the brainstem system which synchronizes hippocampal activity. Theta relevant intra-PPN circuitry involves its cholinergic, GABA-ergic and glutamatergic neurons and Substance P as neuromodulator. Evidence that PPN opioid elements also modulate the hippocampal theta is provided here.