Fenfluramine and other neuroendocrine challenge studies

Another index of serotonergic function is the fenfluramine challenge test. Fenfluramine is a serotonin-releasing agent, as well as a reuptake inhibitor, that may also directly stimulate postsynaptic 5-HT receptors. Because the release of serotonin causes a measurable increase in serum prolactin levels, the fenfluramine challenge test provides an indirect probe of central serotonergic functioning. Most studies have found that depressed subjects have a blunted prolactin response to fenfluramine challenge compared to controls.(17) Flory et al.1) have shown that the blunted response is a trait marker that persists after the depression remits.

Four studies have now reported an association between a prolactin response to fenfluramine and a history of suicide attempts. (3) We have reported that the degree of prolactin blunting distinguishes depressed subjects with serious past suicide attempts from depressed subjects with less serious attempts. Interestingly, New et al.(13 found a blunted prolactin response in subjects with a history of either suicide attempts or repeated self-mutilatory behaviours. While any neuroendocrine challenge involves several interacting neurophysiological systems, there is mounting evidence that the prolactin response to fenfluramine is indeed mediated primarily by serotonin/3,17> Thus the fenfluramine challenge test supplies independent evidence for the role of serotonin in suicidal behaviour. (2)

Coccaro et al. (29 have shown that blunted prolactin response correlated with scores on three scales of aggression and impulsivity, as well as correlating with a direct laboratory measure of aggressive behaviour, the Point-Subtraction Aggression Paradigm ( PSAP). Moeller et al.(21) also used the PSAP in conjunction with ipsapirone, a specific 5-HT1A agonist, and found that subjects with a high aggression score had a significantly blunted temperature response to ipsapirone compared with those with a lower score.

Finally, Coccaro et al.(22) also found that a blunted prolactin response predicted impulsive personality disorder traits in the first-degree relatives of patients with a primary DSM-III diagnosis of a personality disorder. This was a more sensitive parameter for identifying this familial trait than the presence of impulsive or aggressive behaviours in the proband.

Breaking Bulimia

Breaking Bulimia

We have all been there: turning to the refrigerator if feeling lonely or bored or indulging in seconds or thirds if strained. But if you suffer from bulimia, the from time to time urge to overeat is more like an obsession.

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