Pressor effects of electrical stimulation of medial prefrontal cortex in unanesthetized rats.
The medial prefrontal cortex (MPFC) is involved in central nervous system (CNS)-mediated cardiovascular modulation. We compared the cardiovascular effects of electrical stimulation (EE) of the MPFC in unanesthetized rats to those observed after stimulation of the same area in urethane-anesthetized rats. Electrical stimulation (35, 106, 177, 247, 318, and 389 microA rms/10 sec, 60-Hz sine wave) of the MPFC of urethane-anesthetized rats caused depressor responses of stimulus-related intensity. The cardiovascular response to electrical stimulation of the MPFC in unanesthetized rats was characterized by stimulus-related pressor responses. No significant heart rate changes were observed during the EE period in any case. The pressor response to electrical stimulation (106 microA rms/10 sec, 60-Hz sine wave) of the MPFC was not affected by intravenous pretreatment with the vasopressin antagonist dTyr(CH(2))(5)(Me)AVP (50 microg/kg, intravenously), by hypophysectomy, or by intravenous pretreatment with the angiotensin II antagonist losartan (1 mg/kg, intravenously). The pressor response was blocked by intravenous pretreatment with the ganglionic blocker mecamylamine (2 mg/kg, intravenously) but was not affected by adrenal demedullation, thus suggesting involvement of the neural component of the sympathetic nervous system without a major involvement of its hormonal component. Our results confirmed the occurrence of depressor responses after electrical stimulation of the MPFC in urethane-anesthetized rats and evidenced that only pressor responses are observed after its stimulation in unanesthetized rats. The fact that the pressor response to the stimulation of the MPFC was blocked by a ganglioplegic suggests that the MPFC has functional excitatory actions over the sympathetic nervous system.
Tavares
Rodrigo Fiacadori
RF
Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
Antunes-Rodrigues
José
J
de Aguiar Corrêa
Fernando Morgan
FM
D000313:Adrenal Medulla / Q000293:injuries / Q000294:innervation / Q000502:physiology; D000804:Angiotensin II / Q000037:antagonists & inhibitors / Q000378:metabolism; D000818:Animals; D017776:Autonomic Pathways / Q000187:drug effects / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D003714:Denervation; D004525:Efferent Pathways / Q000187:drug effects / Q000502:physiology*; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D005728:Ganglia, Sympathetic / Q000187:drug effects / Q000502:physiology; D019808:Losartan / Q000494:pharmacology; D008297:Male; D008464:Mecamylamine / Q000494:pharmacology; D017397:Prefrontal Cortex / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology*; D014520:Urethane / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*; D014667:Vasopressins / Q000037:antagonists & inhibitors; D014851:Wakefulness / Q000502:physiology
D014667:Vasopressins; D000804:Angiotensin II; D014520:Urethane; D008464:Mecamylamine; D019808:Losartan