Penile Erection in Conscious Animals
Ex Copula Erections
The ex copula model was a commonly used unanesthetized rat model of erection; however, it has fallen out of favor in recent years due to its limitations. The rat is lightly restrained in a supine position, and the penis is retracted from the sheath. Relatively predictable “sponta-neous” penile erections are thus elicited. The effects of drugs administered into the CNS and CNS lesions have been examined in this model. It has the advantage in that it does not involve social interaction with the female and it exam-ines penile reactions directly. However, the rats must be trained before if they are to stop strug-gling during the testing, and invasive measure-ments of neural activity or hemodynamics are not easily performed. Furthermore, the stimuli eliciting these erectile responses are unclear. Sildenafil citrate Australia - information about viagra in Australia.
Noncontact erection
Noncontact erection (NCE) is a centrally gener-ated erection model in conscious rats. Pigmented strains of male rats develop penile erections in response to the presence of estrous female even when physical contact is prevented. Volatile odors from the estrous females have been shown to be the necessary and sufficient stimulus for this response. Note that this response is mediated by the vomeronasal organ and the accessory olfactory system (pathways for the processing of pheromone stimuli), not the main olfactory sys-tem responsible for the sense of smell. This model is the first in which erections are generated by environmental sexual stimuli, without genital stimulation, possibly similar to psychogenic erec-tions in the human. However, there is little evi-dence that pheromonal cues play any significant role in sexual arousal in humans. Thus, it is likely that NCEs in rats and psychogenic erections in humans are mediated by very different forebrain sensory mechanisms. Nonetheless, this is a model of a physiologically relevant, CNS-driven erec-tion in unanesthetized animals, without the con-founding complex social and sensory stimuli of copulatory behavior.
Models of Erectile Dysfunction
A wide variety of pathophysiological models of ED have been proposed aiming to mimic the numerous pathological conditions responsible for ED in humans. The most common of these models are hypertensive rats, atherosclerotic rab-bits, diabetic rats and rabbits, aged rats, castrated rats, and cavernous nerve-injured rats. Our under-standing about the molecular mechanisms involved in the physiology of penile erection has advanced significantly in the last decade as a direct result of the use of animal models to study aberrant erectile mechanisms in various patho-logical situations. Viagra Australia shop The purpose of this subchapter is to evaluate experimental disease animal models used to study ED and further our understanding of species choice and end points associated with each animal model. These models have undoubt-edly been useful, but caution must be observed on how closely they mimic human conditions.