Central tegmental field and sexual behavior in the male rat: Effects of neurotoxic lesions

• Published in: Neuroscience 2007-09, Vol.148 (4), p.867-875
• Main Authors: Romero-Carbente, J.C, Hurtazo, E.A, Paredes, R.G
• Format: Article
• Language: English
• Subjects: Analysis of Variance; Animals; Behavior, Animal - drug effects; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Glial Fibrillary Acidic Protein - metabolism; Male; male sexual behavior; Motor Activity - drug effects; motor execution; Neurology; neurotoxic lesion; Neurotoxins - toxicity; partner preference; Phosphopyruvate Hydratase - metabolism; Quinolinic Acid - toxicity; Rats; Rats, Wistar; Reaction Time - drug effects; Reaction Time - physiology; Sexual Behavior, Animal - drug effects; Sexual Behavior, Animal - physiology; sexual incentive motivation; Social Behavior; sociosexual behavior; Statistics, Nonparametric; Tegmentum Mesencephali - injuries; Tegmentum Mesencephali - physiology; Vertebrates: nervous system and sense organs
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/j.neuroscience.2007.07.008

Abstract The medial preoptic area/anterior hypothalamus (MPOA/AH) is a key structure in the control of male sexual behavior. This area has reciprocal connections with mesencephalic and brainstem structures including the central tegmental field (CTF). It has been suggested that the CTF receives somatosensory information generated in the genitals promoting activation of the MPOA/AH. In the present study we evaluated the effects of bilateral neurotoxic lesions of the CTF upon male rat sexual behavior. We also explored the effects of these lesions on sociosexual behaviors, partner preference, sexual incentive motivation and motor execution. Tests were performed before and after bilateral quinolinic acid infusions. The lesion was evaluated by quantifying neuronal nuclei (Neu-N) and by the presence of glial fibrillary acidic protein (GFAP) immunohistochemistries. A significant reduction in the percentage of animals displaying mounts, intromissions, and ejaculations was observed in the bilateral and misplaced lesion groups 1 week after the lesion. In the second week post-lesion, only animals with bilateral damage of the CTF showed a significant reduction in sexual behavior. In the third post-lesion test, the percentage of animals displaying sexual behavior returned to control levels. The frequency of pursuit and self-grooming was reduced, and genital exploration was increased after the lesion. Partner preference and sexual incentive motivation were not affected by the lesion suggesting that the CTF is not involved in the appetitive aspects of sexual behavior. Mount, intromission, and ejaculation latency were increased in animals with damage of the CTF and in animals with lesions outside this region. Motor execution was also affected in both groups, suggesting that alterations in latencies could be associated with damage not specific to the CTF.