Microlesions of the ventromedial nucleus of the hypothalamus: effects on sociosexual behaviors in male rats.
Electrolytic microlesions aimed at the dorsomedial portion of the ventromedial nucleus (VMN) of the hypothalamus were generated, and effects on copulation, 50-kHz vocalizations, scent marking, and sexual motivation were measured. Male rats were tested before and after lesions, after castration, and after testosterone replacement. Three control groups were used: One received sham surgery, another received no surgery or testosterone replacement, and a 3rd received lesions primarily outside the VMN. VMN lesions produced impairments in testosterone's ability to restore ultrasonic vocalizations and scent marking, assessed with 2 different test methods. Copulation, sexual motivation, and weight gain were largely unaffected, although some differences were observed in copulatory efficiency. The authors conclude that the integrity of the VMN is important for full expression of sociosexual behaviors in male rats.
Harding
Shannon M
SM
Center for Anatomy and Functional Morphology, Mount Sinai School of Medicine, USA. sharding@mail.fairfield.edu
McGinnis
Marilyn Y
MY
D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D001835:Body Weight / Q000502:physiology; D002369:Castration / Q000379:methods; D003216:Conditioning, Operant / Q000187:drug effects / Q000502:physiology; D005260:Female; D008297:Male; D051381:Rats; D020318:Rats, Long-Evans; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D012726:Sexual Behavior, Animal / Q000502:physiology*; D012919:Social Behavior; D013739:Testosterone / Q000008:administration & dosage; D013997:Time Factors; D014697:Ventromedial Hypothalamic Nucleus / Q000187:drug effects / Q000293:injuries* / Q000503:physiopathology*; D014828:Vocalization, Animal / Q000187:drug effects / Q000502:physiology
D013739:Testosterone