Effects of exposure to an estrous female on forebrain monoaminergic neurotransmission in the non-copulating male rat.
Regional changes in the rate of brain monoamine synthesis were monitored in male rats exposed to, but prevented from physical contact with, an estrous or an ovariectomized female. The in vivo rate of tyrosine and tryptophan hydroxylase activities were estimated by measuring the accumulation of DOPA and 5-HTP following inhibition of cerebral aromatic L-amino acid decarboxylase by means of 3-hydroxybenzylhydrazine (NSD-1015) treatment (100 mg/kg i.p.). 5 min upon NSD-1015 treatment, the males were exposed to an intact estrous female or an ovariectomized female for 20 min before decapitation and brain dissections. Exposure to an estrous female produced an increased rate of tyrosine and tryptophan hydroxylase activity in the medial prefrontal cortex, the dorso-lateral neostriatum and in the ventral neostriatum, in comparison with home-cage controls. By the same comparison, exposure to an ovariectomized female resulted in an increased rate of tyrosine hydroxylase activity in the medial prefrontal cortex, but not in the neostriatal areas, whereas tryptophan hydroxylase activity was unaffected. Finally, exposure to the empty test cage, with no stimulus females present, did not produce any statistically significant changes in the rate of tyrosine or tryptophan hydroxylase activity in any of the brain areas sampled. Taken together with recent findings from this laboratory, the present results demonstrate that the level of sexual motivation brought about by the olfactory, auditory and/or visual stimulation of a receptive female is associated with an increased demand on catecholamine and 5-hydroxytryptamine synthesis in the limbic forebrain of the male rat.(ABSTRACT TRUNCATED AT 250 WORDS)
Vega-Matuszczyk
J
J
Department of Psychology, University of Göteborg, Sweden.
Hillegaart
V
V
Larsson
K
K
Ahlenius
S
S
D000161:Acoustic Stimulation; D000818:Animals; D015306:Biogenic Monoamines / Q000096:biosynthesis*; D003307:Copulation / Q000502:physiology; D004295:Dihydroxyphenylalanine / Q000378:metabolism; D004971:Estrus / Q000502:physiology*; D005260:Female; D008297:Male; D009833:Olfactory Pathways / Q000502:physiology; D010052:Ovariectomy; D010053:Ovary / Q000502:physiology; D010775:Photic Stimulation; D016548:Prosencephalon / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism; D009435:Synaptic Transmission / Q000502:physiology*
D015306:Biogenic Monoamines; D012701:Serotonin; D004295:Dihydroxyphenylalanine